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cmd/dist: copy needed packages from standard library during bootstrap

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This allows use of newer math/big (and later debug/pe)
without maintaining a vendored copy somewhere in cmd.

Use for math/big, deleting cmd/compile/internal/big.

Change-Id: I2bffa7a9ef115015be29fafdb02acc3e7a665d11
Reviewed-on: https://go-review.googlesource.com/31010
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Russ Cox 2016-10-13 15:13:41 -04:00
parent f444b48fe4
commit 15040c11b9
46 changed files with 80 additions and 15478 deletions
Download patch file Download diff file Expand all files Collapse all files

6
src/cmd/compile/fmt_test.go
View file

@ -506,9 +506,7 @@ func formatReplace(in string, f func(i int, s string) string) string {
// blacklistedPackages is the set of packages which can // blacklistedPackages is the set of packages which can
// be ignored. // be ignored.
var blacklistedPackages = map[string]bool{ var blacklistedPackages = map[string]bool{}
"cmd/compile/internal/big": true,
}
// blacklistedFunctions is the set of functions which may have // blacklistedFunctions is the set of functions which may have
// format-like arguments but which don't do any formatting and // format-like arguments but which don't do any formatting and
@ -537,7 +535,7 @@ func init() {
// To print out a new table, run: go test -run Formats -v. // To print out a new table, run: go test -run Formats -v.
var knownFormats = map[string]string{ var knownFormats = map[string]string{
"*bytes.Buffer %s": "", "*bytes.Buffer %s": "",
"*cmd/compile/internal/big.Int %#x": "", "*math/big.Int %#x": "",
"*cmd/compile/internal/gc.Bits %v": "", "*cmd/compile/internal/gc.Bits %v": "",
"*cmd/compile/internal/gc.Field %p": "", "*cmd/compile/internal/gc.Field %p": "",
"*cmd/compile/internal/gc.Field %v": "", "*cmd/compile/internal/gc.Field %v": "",

17
src/cmd/compile/internal/big/accuracy_string.go
View file

@ -1,17 +0,0 @@
// generated by stringer -type=Accuracy; DO NOT EDIT
package big
import "fmt"
const _Accuracy_name = "BelowExactAbove"
var _Accuracy_index = [...]uint8{0, 5, 10, 15}
func (i Accuracy) String() string {
i -= -1
if i < 0 || i+1 >= Accuracy(len(_Accuracy_index)) {
return fmt.Sprintf("Accuracy(%d)", i+-1)
}
return _Accuracy_name[_Accuracy_index[i]:_Accuracy_index[i+1]]
}

305
src/cmd/compile/internal/big/arith.go
View file

@ -1,305 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file provides Go implementations of elementary multi-precision
// arithmetic operations on word vectors. Needed for platforms without
// assembly implementations of these routines.
package big
// A Word represents a single digit of a multi-precision unsigned integer.
type Word uintptr
const (
// Compute the size _S of a Word in bytes.
_m = ^Word(0)
_logS = _m>>8&1 + _m>>16&1 + _m>>32&1
_S = 1 << _logS
_W = _S << 3 // word size in bits
_B = 1 << _W // digit base
_M = _B - 1 // digit mask
_W2 = _W / 2 // half word size in bits
_B2 = 1 << _W2 // half digit base
_M2 = _B2 - 1 // half digit mask
)
// ----------------------------------------------------------------------------
// Elementary operations on words
//
// These operations are used by the vector operations below.
// z1<<_W + z0 = x+y+c, with c == 0 or 1
func addWW_g(x, y, c Word) (z1, z0 Word) {
yc := y + c
z0 = x + yc
if z0 < x || yc < y {
z1 = 1
}
return
}
// z1<<_W + z0 = x-y-c, with c == 0 or 1
func subWW_g(x, y, c Word) (z1, z0 Word) {
yc := y + c
z0 = x - yc
if z0 > x || yc < y {
z1 = 1
}
return
}
// z1<<_W + z0 = x*y
// Adapted from Warren, Hacker's Delight, p. 132.
func mulWW_g(x, y Word) (z1, z0 Word) {
x0 := x & _M2
x1 := x >> _W2
y0 := y & _M2
y1 := y >> _W2
w0 := x0 * y0
t := x1*y0 + w0>>_W2
w1 := t & _M2
w2 := t >> _W2
w1 += x0 * y1
z1 = x1*y1 + w2 + w1>>_W2
z0 = x * y
return
}
// z1<<_W + z0 = x*y + c
func mulAddWWW_g(x, y, c Word) (z1, z0 Word) {
z1, zz0 := mulWW_g(x, y)
if z0 = zz0 + c; z0 < zz0 {
z1++
}
return
}
// Length of x in bits.
func bitLen_g(x Word) (n int) {
for ; x >= 0x8000; x >>= 16 {
n += 16
}
if x >= 0x80 {
x >>= 8
n += 8
}
if x >= 0x8 {
x >>= 4
n += 4
}
if x >= 0x2 {
x >>= 2
n += 2
}
if x >= 0x1 {
n++
}
return
}
// log2 computes the integer binary logarithm of x.
// The result is the integer n for which 2^n <= x < 2^(n+1).
// If x == 0, the result is -1.
func log2(x Word) int {
return bitLen(x) - 1
}
// nlz returns the number of leading zeros in x.
func nlz(x Word) uint {
return uint(_W - bitLen(x))
}
// nlz64 returns the number of leading zeros in x.
func nlz64(x uint64) uint {
switch _W {
case 32:
w := x >> 32
if w == 0 {
return 32 + nlz(Word(x))
}
return nlz(Word(w))
case 64:
return nlz(Word(x))
}
panic("unreachable")
}
// q = (u1<<_W + u0 - r)/y
// Adapted from Warren, Hacker's Delight, p. 152.
func divWW_g(u1, u0, v Word) (q, r Word) {
if u1 >= v {
return 1<<_W - 1, 1<<_W - 1
}
s := nlz(v)
v <<= s
vn1 := v >> _W2
vn0 := v & _M2
un32 := u1<<s | u0>>(_W-s)
un10 := u0 << s
un1 := un10 >> _W2
un0 := un10 & _M2
q1 := un32 / vn1
rhat := un32 - q1*vn1
for q1 >= _B2 || q1*vn0 > _B2*rhat+un1 {
q1--
rhat += vn1
if rhat >= _B2 {
break
}
}
un21 := un32*_B2 + un1 - q1*v
q0 := un21 / vn1
rhat = un21 - q0*vn1
for q0 >= _B2 || q0*vn0 > _B2*rhat+un0 {
q0--
rhat += vn1
if rhat >= _B2 {
break
}
}
return q1*_B2 + q0, (un21*_B2 + un0 - q0*v) >> s
}
// Keep for performance debugging.
// Using addWW_g is likely slower.
const use_addWW_g = false
// The resulting carry c is either 0 or 1.
func addVV_g(z, x, y []Word) (c Word) {
if use_addWW_g {
for i := range z {
c, z[i] = addWW_g(x[i], y[i], c)
}
return
}
for i, xi := range x[:len(z)] {
yi := y[i]
zi := xi + yi + c
z[i] = zi
// see "Hacker's Delight", section 2-12 (overflow detection)
c = (xi&yi | (xi|yi)&^zi) >> (_W - 1)
}
return
}
// The resulting carry c is either 0 or 1.
func subVV_g(z, x, y []Word) (c Word) {
if use_addWW_g {
for i := range z {
c, z[i] = subWW_g(x[i], y[i], c)
}
return
}
for i, xi := range x[:len(z)] {
yi := y[i]
zi := xi - yi - c
z[i] = zi
// see "Hacker's Delight", section 2-12 (overflow detection)
c = (yi&^xi | (yi|^xi)&zi) >> (_W - 1)
}
return
}
// The resulting carry c is either 0 or 1.
func addVW_g(z, x []Word, y Word) (c Word) {
if use_addWW_g {
c = y
for i := range z {
c, z[i] = addWW_g(x[i], c, 0)
}
return
}
c = y
for i, xi := range x[:len(z)] {
zi := xi + c
z[i] = zi
c = xi &^ zi >> (_W - 1)
}
return
}
func subVW_g(z, x []Word, y Word) (c Word) {
if use_addWW_g {
c = y
for i := range z {
c, z[i] = subWW_g(x[i], c, 0)
}
return
}
c = y
for i, xi := range x[:len(z)] {
zi := xi - c
z[i] = zi
c = (zi &^ xi) >> (_W - 1)
}
return
}
func shlVU_g(z, x []Word, s uint) (c Word) {
if n := len(z); n > 0 {
ŝ := _W - s
w1 := x[n-1]
c = w1 >> ŝ
for i := n - 1; i > 0; i-- {
w := w1
w1 = x[i-1]
z[i] = w<<s | w1>>ŝ
}
z[0] = w1 << s
}
return
}
func shrVU_g(z, x []Word, s uint) (c Word) {
if n := len(z); n > 0 {
ŝ := _W - s
w1 := x[0]
c = w1 << ŝ
for i := 0; i < n-1; i++ {
w := w1
w1 = x[i+1]
z[i] = w>>s | w1<<ŝ
}
z[n-1] = w1 >> s
}
return
}
func mulAddVWW_g(z, x []Word, y, r Word) (c Word) {
c = r
for i := range z {
c, z[i] = mulAddWWW_g(x[i], y, c)
}
return
}
// TODO(gri) Remove use of addWW_g here and then we can remove addWW_g and subWW_g.
func addMulVVW_g(z, x []Word, y Word) (c Word) {
for i := range z {
z1, z0 := mulAddWWW_g(x[i], y, z[i])
c, z[i] = addWW_g(z0, c, 0)
c += z1
}
return
}
func divWVW_g(z []Word, xn Word, x []Word, y Word) (r Word) {
r = xn
for i := len(z) - 1; i >= 0; i-- {
z[i], r = divWW_g(r, x[i], y)
}
return
}

53
src/cmd/compile/internal/big/arith_decl.go
View file

@ -1,53 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
func mulWW(x, y Word) (z1, z0 Word) {
return mulWW_g(x, y)
}
func divWW(x1, x0, y Word) (q, r Word) {
return divWW_g(x1, x0, y)
}
func addVV(z, x, y []Word) (c Word) {
return addVV_g(z, x, y)
}
func subVV(z, x, y []Word) (c Word) {
return subVV_g(z, x, y)
}
func addVW(z, x []Word, y Word) (c Word) {
return addVW_g(z, x, y)
}
func subVW(z, x []Word, y Word) (c Word) {
return subVW_g(z, x, y)
}
func shlVU(z, x []Word, s uint) (c Word) {
return shlVU_g(z, x, s)
}
func shrVU(z, x []Word, s uint) (c Word) {
return shrVU_g(z, x, s)
}
func mulAddVWW(z, x []Word, y, r Word) (c Word) {
return mulAddVWW_g(z, x, y, r)
}
func addMulVVW(z, x []Word, y Word) (c Word) {
return addMulVVW_g(z, x, y)
}
func divWVW(z []Word, xn Word, x []Word, y Word) (r Word) {
return divWVW_g(z, xn, x, y)
}
func bitLen(x Word) (n int) {
return bitLen_g(x)
}

413
src/cmd/compile/internal/big/arith_test.go
View file

@ -1,413 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"fmt"
"math/rand"
"testing"
)
type funWW func(x, y, c Word) (z1, z0 Word)
type argWW struct {
x, y, c, z1, z0 Word
}
var sumWW = []argWW{
{0, 0, 0, 0, 0},
{0, 1, 0, 0, 1},
{0, 0, 1, 0, 1},
{0, 1, 1, 0, 2},
{12345, 67890, 0, 0, 80235},
{12345, 67890, 1, 0, 80236},
{_M, 1, 0, 1, 0},
{_M, 0, 1, 1, 0},
{_M, 1, 1, 1, 1},
{_M, _M, 0, 1, _M - 1},
{_M, _M, 1, 1, _M},
}
func testFunWW(t *testing.T, msg string, f funWW, a argWW) {
z1, z0 := f(a.x, a.y, a.c)
if z1 != a.z1 || z0 != a.z0 {
t.Errorf("%s%+v\n\tgot z1:z0 = %#x:%#x; want %#x:%#x", msg, a, z1, z0, a.z1, a.z0)
}
}
func TestFunWW(t *testing.T) {
for _, a := range sumWW {
arg := a
testFunWW(t, "addWW_g", addWW_g, arg)
arg = argWW{a.y, a.x, a.c, a.z1, a.z0}
testFunWW(t, "addWW_g symmetric", addWW_g, arg)
arg = argWW{a.z0, a.x, a.c, a.z1, a.y}
testFunWW(t, "subWW_g", subWW_g, arg)
arg = argWW{a.z0, a.y, a.c, a.z1, a.x}
testFunWW(t, "subWW_g symmetric", subWW_g, arg)
}
}
type funVV func(z, x, y []Word) (c Word)
type argVV struct {
z, x, y nat
c Word
}
var sumVV = []argVV{
{},
{nat{0}, nat{0}, nat{0}, 0},
{nat{1}, nat{1}, nat{0}, 0},
{nat{0}, nat{_M}, nat{1}, 1},
{nat{80235}, nat{12345}, nat{67890}, 0},
{nat{_M - 1}, nat{_M}, nat{_M}, 1},
{nat{0, 0, 0, 0}, nat{_M, _M, _M, _M}, nat{1, 0, 0, 0}, 1},
{nat{0, 0, 0, _M}, nat{_M, _M, _M, _M - 1}, nat{1, 0, 0, 0}, 0},
{nat{0, 0, 0, 0}, nat{_M, 0, _M, 0}, nat{1, _M, 0, _M}, 1},
}
func testFunVV(t *testing.T, msg string, f funVV, a argVV) {
z := make(nat, len(a.z))
c := f(z, a.x, a.y)
for i, zi := range z {
if zi != a.z[i] {
t.Errorf("%s%+v\n\tgot z[%d] = %#x; want %#x", msg, a, i, zi, a.z[i])
break
}
}
if c != a.c {
t.Errorf("%s%+v\n\tgot c = %#x; want %#x", msg, a, c, a.c)
}
}
func TestFunVV(t *testing.T) {
for _, a := range sumVV {
arg := a
testFunVV(t, "addVV_g", addVV_g, arg)
testFunVV(t, "addVV", addVV, arg)
arg = argVV{a.z, a.y, a.x, a.c}
testFunVV(t, "addVV_g symmetric", addVV_g, arg)
testFunVV(t, "addVV symmetric", addVV, arg)
arg = argVV{a.x, a.z, a.y, a.c}
testFunVV(t, "subVV_g", subVV_g, arg)
testFunVV(t, "subVV", subVV, arg)
arg = argVV{a.y, a.z, a.x, a.c}
testFunVV(t, "subVV_g symmetric", subVV_g, arg)
testFunVV(t, "subVV symmetric", subVV, arg)
}
}
// Always the same seed for reproducible results.
var rnd = rand.New(rand.NewSource(0))
func rndW() Word {
return Word(rnd.Int63()<<1 | rnd.Int63n(2))
}
func rndV(n int) []Word {
v := make([]Word, n)
for i := range v {
v[i] = rndW()
}
return v
}
var benchSizes = []int{1, 2, 3, 4, 5, 1e1, 1e2, 1e3, 1e4, 1e5}
func BenchmarkAddVV(b *testing.B) {
for _, n := range benchSizes {
x := rndV(n)
y := rndV(n)
z := make([]Word, n)
b.Run(fmt.Sprint(n), func(b *testing.B) {
b.SetBytes(int64(n * _W))
for i := 0; i < b.N; i++ {
addVV(z, x, y)
}
})
}
}
type funVW func(z, x []Word, y Word) (c Word)
type argVW struct {
z, x nat
y Word
c Word
}
var sumVW = []argVW{
{},
{nil, nil, 2, 2},
{nat{0}, nat{0}, 0, 0},
{nat{1}, nat{0}, 1, 0},
{nat{1}, nat{1}, 0, 0},
{nat{0}, nat{_M}, 1, 1},
{nat{0, 0, 0, 0}, nat{_M, _M, _M, _M}, 1, 1},
{nat{585}, nat{314}, 271, 0},
}
var lshVW = []argVW{
{},
{nat{0}, nat{0}, 0, 0},
{nat{0}, nat{0}, 1, 0},
{nat{0}, nat{0}, 20, 0},
{nat{_M}, nat{_M}, 0, 0},
{nat{_M << 1 & _M}, nat{_M}, 1, 1},
{nat{_M << 20 & _M}, nat{_M}, 20, _M >> (_W - 20)},
{nat{_M, _M, _M}, nat{_M, _M, _M}, 0, 0},
{nat{_M << 1 & _M, _M, _M}, nat{_M, _M, _M}, 1, 1},
{nat{_M << 20 & _M, _M, _M}, nat{_M, _M, _M}, 20, _M >> (_W - 20)},
}
var rshVW = []argVW{
{},
{nat{0}, nat{0}, 0, 0},
{nat{0}, nat{0}, 1, 0},
{nat{0}, nat{0}, 20, 0},
{nat{_M}, nat{_M}, 0, 0},
{nat{_M >> 1}, nat{_M}, 1, _M << (_W - 1) & _M},
{nat{_M >> 20}, nat{_M}, 20, _M << (_W - 20) & _M},
{nat{_M, _M, _M}, nat{_M, _M, _M}, 0, 0},
{nat{_M, _M, _M >> 1}, nat{_M, _M, _M}, 1, _M << (_W - 1) & _M},
{nat{_M, _M, _M >> 20}, nat{_M, _M, _M}, 20, _M << (_W - 20) & _M},
}
func testFunVW(t *testing.T, msg string, f funVW, a argVW) {
z := make(nat, len(a.z))
c := f(z, a.x, a.y)
for i, zi := range z {
if zi != a.z[i] {
t.Errorf("%s%+v\n\tgot z[%d] = %#x; want %#x", msg, a, i, zi, a.z[i])
break
}
}
if c != a.c {
t.Errorf("%s%+v\n\tgot c = %#x; want %#x", msg, a, c, a.c)
}
}
func makeFunVW(f func(z, x []Word, s uint) (c Word)) funVW {
return func(z, x []Word, s Word) (c Word) {
return f(z, x, uint(s))
}
}
func TestFunVW(t *testing.T) {
for _, a := range sumVW {
arg := a
testFunVW(t, "addVW_g", addVW_g, arg)
testFunVW(t, "addVW", addVW, arg)
arg = argVW{a.x, a.z, a.y, a.c}
testFunVW(t, "subVW_g", subVW_g, arg)
testFunVW(t, "subVW", subVW, arg)
}
shlVW_g := makeFunVW(shlVU_g)
shlVW := makeFunVW(shlVU)
for _, a := range lshVW {
arg := a
testFunVW(t, "shlVU_g", shlVW_g, arg)
testFunVW(t, "shlVU", shlVW, arg)
}
shrVW_g := makeFunVW(shrVU_g)
shrVW := makeFunVW(shrVU)
for _, a := range rshVW {
arg := a
testFunVW(t, "shrVU_g", shrVW_g, arg)
testFunVW(t, "shrVU", shrVW, arg)
}
}
func BenchmarkAddVW(b *testing.B) {
for _, n := range benchSizes {
x := rndV(n)
y := rndW()
z := make([]Word, n)
b.Run(fmt.Sprint(n), func(b *testing.B) {
b.SetBytes(int64(n * _S))
for i := 0; i < b.N; i++ {
addVW(z, x, y)
}
})
}
}
type funVWW func(z, x []Word, y, r Word) (c Word)
type argVWW struct {
z, x nat
y, r Word
c Word
}
var prodVWW = []argVWW{
{},
{nat{0}, nat{0}, 0, 0, 0},
{nat{991}, nat{0}, 0, 991, 0},
{nat{0}, nat{_M}, 0, 0, 0},
{nat{991}, nat{_M}, 0, 991, 0},
{nat{0}, nat{0}, _M, 0, 0},
{nat{991}, nat{0}, _M, 991, 0},
{nat{1}, nat{1}, 1, 0, 0},
{nat{992}, nat{1}, 1, 991, 0},
{nat{22793}, nat{991}, 23, 0, 0},
{nat{22800}, nat{991}, 23, 7, 0},
{nat{0, 0, 0, 22793}, nat{0, 0, 0, 991}, 23, 0, 0},
{nat{7, 0, 0, 22793}, nat{0, 0, 0, 991}, 23, 7, 0},
{nat{0, 0, 0, 0}, nat{7893475, 7395495, 798547395, 68943}, 0, 0, 0},
{nat{991, 0, 0, 0}, nat{7893475, 7395495, 798547395, 68943}, 0, 991, 0},
{nat{0, 0, 0, 0}, nat{0, 0, 0, 0}, 894375984, 0, 0},
{nat{991, 0, 0, 0}, nat{0, 0, 0, 0}, 894375984, 991, 0},
{nat{_M << 1 & _M}, nat{_M}, 1 << 1, 0, _M >> (_W - 1)},
{nat{_M<<1&_M + 1}, nat{_M}, 1 << 1, 1, _M >> (_W - 1)},
{nat{_M << 7 & _M}, nat{_M}, 1 << 7, 0, _M >> (_W - 7)},
{nat{_M<<7&_M + 1<<6}, nat{_M}, 1 << 7, 1 << 6, _M >> (_W - 7)},
{nat{_M << 7 & _M, _M, _M, _M}, nat{_M, _M, _M, _M}, 1 << 7, 0, _M >> (_W - 7)},
{nat{_M<<7&_M + 1<<6, _M, _M, _M}, nat{_M, _M, _M, _M}, 1 << 7, 1 << 6, _M >> (_W - 7)},
}
func testFunVWW(t *testing.T, msg string, f funVWW, a argVWW) {
z := make(nat, len(a.z))
c := f(z, a.x, a.y, a.r)
for i, zi := range z {
if zi != a.z[i] {
t.Errorf("%s%+v\n\tgot z[%d] = %#x; want %#x", msg, a, i, zi, a.z[i])
break
}
}
if c != a.c {
t.Errorf("%s%+v\n\tgot c = %#x; want %#x", msg, a, c, a.c)
}
}
// TODO(gri) mulAddVWW and divWVW are symmetric operations but
// their signature is not symmetric. Try to unify.
type funWVW func(z []Word, xn Word, x []Word, y Word) (r Word)
type argWVW struct {
z nat
xn Word
x nat
y Word
r Word
}
func testFunWVW(t *testing.T, msg string, f funWVW, a argWVW) {
z := make(nat, len(a.z))
r := f(z, a.xn, a.x, a.y)
for i, zi := range z {
if zi != a.z[i] {
t.Errorf("%s%+v\n\tgot z[%d] = %#x; want %#x", msg, a, i, zi, a.z[i])
break
}
}
if r != a.r {
t.Errorf("%s%+v\n\tgot r = %#x; want %#x", msg, a, r, a.r)
}
}
func TestFunVWW(t *testing.T) {
for _, a := range prodVWW {
arg := a
testFunVWW(t, "mulAddVWW_g", mulAddVWW_g, arg)
testFunVWW(t, "mulAddVWW", mulAddVWW, arg)
if a.y != 0 && a.r < a.y {
arg := argWVW{a.x, a.c, a.z, a.y, a.r}
testFunWVW(t, "divWVW_g", divWVW_g, arg)
testFunWVW(t, "divWVW", divWVW, arg)
}
}
}
var mulWWTests = []struct {
x, y Word
q, r Word
}{
{_M, _M, _M - 1, 1},
// 32 bit only: {0xc47dfa8c, 50911, 0x98a4, 0x998587f4},
}
func TestMulWW(t *testing.T) {
for i, test := range mulWWTests {
q, r := mulWW_g(test.x, test.y)
if q != test.q || r != test.r {
t.Errorf("#%d got (%x, %x) want (%x, %x)", i, q, r, test.q, test.r)
}
}
}
var mulAddWWWTests = []struct {
x, y, c Word
q, r Word
}{
// TODO(agl): These will only work on 64-bit platforms.
// {15064310297182388543, 0xe7df04d2d35d5d80, 13537600649892366549, 13644450054494335067, 10832252001440893781},
// {15064310297182388543, 0xdab2f18048baa68d, 13644450054494335067, 12869334219691522700, 14233854684711418382},
{_M, _M, 0, _M - 1, 1},
{_M, _M, _M, _M, 0},
}
func TestMulAddWWW(t *testing.T) {
for i, test := range mulAddWWWTests {
q, r := mulAddWWW_g(test.x, test.y, test.c)
if q != test.q || r != test.r {
t.Errorf("#%d got (%x, %x) want (%x, %x)", i, q, r, test.q, test.r)
}
}
}
func BenchmarkAddMulVVW(b *testing.B) {
for _, n := range benchSizes {
x := rndV(n)
y := rndW()
z := make([]Word, n)
b.Run(fmt.Sprint(n), func(b *testing.B) {
b.SetBytes(int64(n * _W))
for i := 0; i < b.N; i++ {
addMulVVW(z, x, y)
}
})
}
}
func testWordBitLen(t *testing.T, fname string, f func(Word) int) {
for i := 0; i <= _W; i++ {
x := Word(1) << uint(i-1) // i == 0 => x == 0
n := f(x)
if n != i {
t.Errorf("got %d; want %d for %s(%#x)", n, i, fname, x)
}
}
}
func TestWordBitLen(t *testing.T) {
testWordBitLen(t, "bitLen", bitLen)
testWordBitLen(t, "bitLen_g", bitLen_g)
}
// runs b.N iterations of bitLen called on a Word containing (1 << nbits)-1.
func BenchmarkBitLen(b *testing.B) {
// Individual bitLen tests. Numbers chosen to examine both sides
// of powers-of-two boundaries.
for _, nbits := range []uint{0, 1, 2, 3, 4, 5, 8, 9, 16, 17, 31} {
testword := Word((uint64(1) << nbits) - 1)
b.Run(fmt.Sprint(nbits), func(b *testing.B) {
for i := 0; i < b.N; i++ {
bitLen(testword)
}
})
}
}

224
src/cmd/compile/internal/big/bits_test.go
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@ -1,224 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements the Bits type used for testing Float operations
// via an independent (albeit slower) representations for floating-point
// numbers.
package big
import (
"fmt"
"sort"
"testing"
)
// A Bits value b represents a finite floating-point number x of the form
//
// x = 2**b[0] + 2**b[1] + ... 2**b[len(b)-1]
//
// The order of slice elements is not significant. Negative elements may be
// used to form fractions. A Bits value is normalized if each b[i] occurs at
// most once. For instance Bits{0, 0, 1} is not normalized but represents the
// same floating-point number as Bits{2}, which is normalized. The zero (nil)
// value of Bits is a ready to use Bits value and represents the value 0.
type Bits []int
func (x Bits) add(y Bits) Bits {
return append(x, y...)
}
func (x Bits) mul(y Bits) Bits {
var p Bits
for _, x := range x {
for _, y := range y {
p = append(p, x+y)
}
}
return p
}
func TestMulBits(t *testing.T) {
for _, test := range []struct {
x, y, want Bits
}{
{nil, nil, nil},
{Bits{}, Bits{}, nil},
{Bits{0}, Bits{0}, Bits{0}},
{Bits{0}, Bits{1}, Bits{1}},
{Bits{1}, Bits{1, 2, 3}, Bits{2, 3, 4}},
{Bits{-1}, Bits{1}, Bits{0}},
{Bits{-10, -1, 0, 1, 10}, Bits{1, 2, 3}, Bits{-9, -8, -7, 0, 1, 2, 1, 2, 3, 2, 3, 4, 11, 12, 13}},
} {
got := fmt.Sprintf("%v", test.x.mul(test.y))
want := fmt.Sprintf("%v", test.want)
if got != want {
t.Errorf("%v * %v = %s; want %s", test.x, test.y, got, want)
}
}
}
// norm returns the normalized bits for x: It removes multiple equal entries
// by treating them as an addition (e.g., Bits{5, 5} => Bits{6}), and it sorts
// the result list for reproducible results.
func (x Bits) norm() Bits {
m := make(map[int]bool)
for _, b := range x {
for m[b] {
m[b] = false
b++
}
m[b] = true
}
var z Bits
for b, set := range m {
if set {
z = append(z, b)
}
}
sort.Ints([]int(z))
return z
}
func TestNormBits(t *testing.T) {
for _, test := range []struct {
x, want Bits
}{
{nil, nil},
{Bits{}, Bits{}},
{Bits{0}, Bits{0}},
{Bits{0, 0}, Bits{1}},
{Bits{3, 1, 1}, Bits{2, 3}},
{Bits{10, 9, 8, 7, 6, 6}, Bits{11}},
} {
got := fmt.Sprintf("%v", test.x.norm())
want := fmt.Sprintf("%v", test.want)
if got != want {
t.Errorf("normBits(%v) = %s; want %s", test.x, got, want)
}
}
}
// round returns the Float value corresponding to x after rounding x
// to prec bits according to mode.
func (x Bits) round(prec uint, mode RoundingMode) *Float {
x = x.norm()
// determine range
var min, max int
for i, b := range x {
if i == 0 || b < min {
min = b
}
if i == 0 || b > max {
max = b
}
}
prec0 := uint(max + 1 - min)
if prec >= prec0 {
return x.Float()
}
// prec < prec0
// determine bit 0, rounding, and sticky bit, and result bits z
var bit0, rbit, sbit uint
var z Bits
r := max - int(prec)
for _, b := range x {
switch {
case b == r:
rbit = 1
case b < r:
sbit = 1
default:
// b > r
if b == r+1 {
bit0 = 1
}
z = append(z, b)
}
}
// round
f := z.Float() // rounded to zero
if mode == ToNearestAway {
panic("not yet implemented")
}
if mode == ToNearestEven && rbit == 1 && (sbit == 1 || sbit == 0 && bit0 != 0) || mode == AwayFromZero {
// round away from zero
f.SetMode(ToZero).SetPrec(prec)
f.Add(f, Bits{int(r) + 1}.Float())
}
return f
}
// Float returns the *Float z of the smallest possible precision such that
// z = sum(2**bits[i]), with i = range bits. If multiple bits[i] are equal,
// they are added: Bits{0, 1, 0}.Float() == 2**0 + 2**1 + 2**0 = 4.
func (bits Bits) Float() *Float {
// handle 0
if len(bits) == 0 {
return new(Float)
}
// len(bits) > 0
// determine lsb exponent
var min int
for i, b := range bits {
if i == 0 || b < min {
min = b
}
}
// create bit pattern
x := NewInt(0)
for _, b := range bits {
badj := b - min
// propagate carry if necessary
for x.Bit(badj) != 0 {
x.SetBit(x, badj, 0)
badj++
}
x.SetBit(x, badj, 1)
}
// create corresponding float
z := new(Float).SetInt(x) // normalized
if e := int64(z.exp) + int64(min); MinExp <= e && e <= MaxExp {
z.exp = int32(e)
} else {
// this should never happen for our test cases
panic("exponent out of range")
}
return z
}
func TestFromBits(t *testing.T) {
for _, test := range []struct {
bits Bits
want string
}{
// all different bit numbers
{nil, "0"},
{Bits{0}, "0x.8p+1"},
{Bits{1}, "0x.8p+2"},
{Bits{-1}, "0x.8p+0"},
{Bits{63}, "0x.8p+64"},
{Bits{33, -30}, "0x.8000000000000001p+34"},
{Bits{255, 0}, "0x.8000000000000000000000000000000000000000000000000000000000000001p+256"},
// multiple equal bit numbers
{Bits{0, 0}, "0x.8p+2"},
{Bits{0, 0, 0, 0}, "0x.8p+3"},
{Bits{0, 1, 0}, "0x.8p+3"},
{append(Bits{2, 1, 0} /* 7 */, Bits{3, 1} /* 10 */ ...), "0x.88p+5" /* 17 */},
} {
f := test.bits.Float()
if got := f.Text('p', 0); got != test.want {
t.Errorf("setBits(%v) = %s; want %s", test.bits, got, test.want)
}
}
}

88
src/cmd/compile/internal/big/calibrate_test.go
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@ -1,88 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file prints execution times for the Mul benchmark
// given different Karatsuba thresholds. The result may be
// used to manually fine-tune the threshold constant. The
// results are somewhat fragile; use repeated runs to get
// a clear picture.
// Usage: go test -run=TestCalibrate -calibrate
package big
import (
"flag"
"fmt"
"testing"
"time"
)
var calibrate = flag.Bool("calibrate", false, "run calibration test")
func karatsubaLoad(b *testing.B) {
BenchmarkMul(b)
}
// measureKaratsuba returns the time to run a Karatsuba-relevant benchmark
// given Karatsuba threshold th.
func measureKaratsuba(th int) time.Duration {
th, karatsubaThreshold = karatsubaThreshold, th
res := testing.Benchmark(karatsubaLoad)
karatsubaThreshold = th
return time.Duration(res.NsPerOp())
}
func computeThresholds() {
fmt.Printf("Multiplication times for varying Karatsuba thresholds\n")
fmt.Printf("(run repeatedly for good results)\n")
// determine Tk, the work load execution time using basic multiplication
Tb := measureKaratsuba(1e9) // th == 1e9 => Karatsuba multiplication disabled
fmt.Printf("Tb = %10s\n", Tb)
// thresholds
th := 4
th1 := -1
th2 := -1
var deltaOld time.Duration
for count := -1; count != 0 && th < 128; count-- {
// determine Tk, the work load execution time using Karatsuba multiplication
Tk := measureKaratsuba(th)
// improvement over Tb
delta := (Tb - Tk) * 100 / Tb
fmt.Printf("th = %3d Tk = %10s %4d%%", th, Tk, delta)
// determine break-even point
if Tk < Tb && th1 < 0 {
th1 = th
fmt.Print(" break-even point")
}
// determine diminishing return
if 0 < delta && delta < deltaOld && th2 < 0 {
th2 = th
fmt.Print(" diminishing return")
}
deltaOld = delta
fmt.Println()
// trigger counter
if th1 >= 0 && th2 >= 0 && count < 0 {
count = 10 // this many extra measurements after we got both thresholds
}
th++
}
}
func TestCalibrate(t *testing.T) {
if *calibrate {
computeThresholds()
}
}

266
src/cmd/compile/internal/big/decimal.go
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@ -1,266 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements multi-precision decimal numbers.
// The implementation is for float to decimal conversion only;
// not general purpose use.
// The only operations are precise conversion from binary to
// decimal and rounding.
//
// The key observation and some code (shr) is borrowed from
// strconv/decimal.go: conversion of binary fractional values can be done
// precisely in multi-precision decimal because 2 divides 10 (required for
// >> of mantissa); but conversion of decimal floating-point values cannot
// be done precisely in binary representation.
//
// In contrast to strconv/decimal.go, only right shift is implemented in
// decimal format - left shift can be done precisely in binary format.
package big
// A decimal represents an unsigned floating-point number in decimal representation.
// The value of a non-zero decimal d is d.mant * 10**d.exp with 0.5 <= d.mant < 1,
// with the most-significant mantissa digit at index 0. For the zero decimal, the
// mantissa length and exponent are 0.
// The zero value for decimal represents a ready-to-use 0.0.
type decimal struct {
mant []byte // mantissa ASCII digits, big-endian
exp int // exponent
}
// at returns the i'th mantissa digit, starting with the most significant digit at 0.
func (d *decimal) at(i int) byte {
if 0 <= i && i < len(d.mant) {
return d.mant[i]
}
return '0'
}
// Maximum shift amount that can be done in one pass without overflow.
// A Word has _W bits and (1<<maxShift - 1)*10 + 9 must fit into Word.
const maxShift = _W - 4
// TODO(gri) Since we know the desired decimal precision when converting
// a floating-point number, we may be able to limit the number of decimal
// digits that need to be computed by init by providing an additional
// precision argument and keeping track of when a number was truncated early
// (equivalent of "sticky bit" in binary rounding).
// TODO(gri) Along the same lines, enforce some limit to shift magnitudes
// to avoid "infinitely" long running conversions (until we run out of space).
// Init initializes x to the decimal representation of m << shift (for
// shift >= 0), or m >> -shift (for shift < 0).
func (x *decimal) init(m nat, shift int) {
// special case 0
if len(m) == 0 {
x.mant = x.mant[:0]
x.exp = 0
return
}
// Optimization: If we need to shift right, first remove any trailing
// zero bits from m to reduce shift amount that needs to be done in
// decimal format (since that is likely slower).
if shift < 0 {
ntz := m.trailingZeroBits()
s := uint(-shift)
if s >= ntz {
s = ntz // shift at most ntz bits
}
m = nat(nil).shr(m, s)
shift += int(s)
}
// Do any shift left in binary representation.
if shift > 0 {
m = nat(nil).shl(m, uint(shift))
shift = 0
}
// Convert mantissa into decimal representation.
s := m.utoa(10)
n := len(s)
x.exp = n
// Trim trailing zeros; instead the exponent is tracking
// the decimal point independent of the number of digits.
for n > 0 && s[n-1] == '0' {
n--
}
x.mant = append(x.mant[:0], s[:n]...)
// Do any (remaining) shift right in decimal representation.
if shift < 0 {
for shift < -maxShift {
shr(x, maxShift)
shift += maxShift
}
shr(x, uint(-shift))
}
}
// shr implements x >> s, for s <= maxShift.
func shr(x *decimal, s uint) {
// Division by 1<<s using shift-and-subtract algorithm.
// pick up enough leading digits to cover first shift
r := 0 // read index
var n Word
for n>>s == 0 && r < len(x.mant) {
ch := Word(x.mant[r])
r++
n = n*10 + ch - '0'
}
if n == 0 {
// x == 0; shouldn't get here, but handle anyway
x.mant = x.mant[:0]
return
}
for n>>s == 0 {
r++
n *= 10
}
x.exp += 1 - r
// read a digit, write a digit
w := 0 // write index
for r < len(x.mant) {
ch := Word(x.mant[r])
r++
d := n >> s
n -= d << s
x.mant[w] = byte(d + '0')
w++
n = n*10 + ch - '0'
}
// write extra digits that still fit
for n > 0 && w < len(x.mant) {
d := n >> s
n -= d << s
x.mant[w] = byte(d + '0')
w++
n = n * 10
}
x.mant = x.mant[:w] // the number may be shorter (e.g. 1024 >> 10)
// append additional digits that didn't fit
for n > 0 {
d := n >> s
n -= d << s
x.mant = append(x.mant, byte(d+'0'))
n = n * 10
}
trim(x)
}
func (x *decimal) String() string {
if len(x.mant) == 0 {
return "0"
}
var buf []byte
switch {
case x.exp <= 0:
// 0.00ddd
buf = append(buf, "0."...)
buf = appendZeros(buf, -x.exp)
buf = append(buf, x.mant...)
case /* 0 < */ x.exp < len(x.mant):
// dd.ddd
buf = append(buf, x.mant[:x.exp]...)
buf = append(buf, '.')
buf = append(buf, x.mant[x.exp:]...)
default: // len(x.mant) <= x.exp
// ddd00
buf = append(buf, x.mant...)
buf = appendZeros(buf, x.exp-len(x.mant))
}
return string(buf)
}
// appendZeros appends n 0 digits to buf and returns buf.
func appendZeros(buf []byte, n int) []byte {
for ; n > 0; n-- {
buf = append(buf, '0')
}
return buf
}
// shouldRoundUp reports if x should be rounded up
// if shortened to n digits. n must be a valid index
// for x.mant.
func shouldRoundUp(x *decimal, n int) bool {
if x.mant[n] == '5' && n+1 == len(x.mant) {
// exactly halfway - round to even
return n > 0 && (x.mant[n-1]-'0')&1 != 0
}
// not halfway - digit tells all (x.mant has no trailing zeros)
return x.mant[n] >= '5'
}
// round sets x to (at most) n mantissa digits by rounding it
// to the nearest even value with n (or fever) mantissa digits.
// If n < 0, x remains unchanged.
func (x *decimal) round(n int) {
if n < 0 || n >= len(x.mant) {
return // nothing to do
}
if shouldRoundUp(x, n) {
x.roundUp(n)
} else {
x.roundDown(n)
}
}
func (x *decimal) roundUp(n int) {
if n < 0 || n >= len(x.mant) {
return // nothing to do
}
// 0 <= n < len(x.mant)
// find first digit < '9'
for n > 0 && x.mant[n-1] >= '9' {
n--
}
if n == 0 {
// all digits are '9's => round up to '1' and update exponent
x.mant[0] = '1' // ok since len(x.mant) > n
x.mant = x.mant[:1]
x.exp++
return
}
// n > 0 && x.mant[n-1] < '9'
x.mant[n-1]++
x.mant = x.mant[:n]
// x already trimmed
}
func (x *decimal) roundDown(n int) {
if n < 0 || n >= len(x.mant) {
return // nothing to do
}
x.mant = x.mant[:n]
trim(x)
}
// trim cuts off any trailing zeros from x's mantissa;
// they are meaningless for the value of x.
func trim(x *decimal) {
i := len(x.mant)
for i > 0 && x.mant[i-1] == '0' {
i--
}
x.mant = x.mant[:i]
if i == 0 {
x.exp = 0
}
}

118
src/cmd/compile/internal/big/decimal_test.go
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@ -1,118 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import "testing"
func TestDecimalString(t *testing.T) {
for _, test := range []struct {
x decimal
want string
}{
{want: "0"},
{decimal{nil, 1000}, "0"}, // exponent of 0 is ignored
{decimal{[]byte("12345"), 0}, "0.12345"},
{decimal{[]byte("12345"), -3}, "0.00012345"},
{decimal{[]byte("12345"), +3}, "123.45"},
{decimal{[]byte("12345"), +10}, "1234500000"},
} {
if got := test.x.String(); got != test.want {
t.Errorf("%v == %s; want %s", test.x, got, test.want)
}
}
}
func TestDecimalInit(t *testing.T) {
for _, test := range []struct {
x Word
shift int
want string
}{
{0, 0, "0"},
{0, -100, "0"},
{0, 100, "0"},
{1, 0, "1"},
{1, 10, "1024"},
{1, 100, "1267650600228229401496703205376"},
{1, -100, "0.0000000000000000000000000000007888609052210118054117285652827862296732064351090230047702789306640625"},
{12345678, 8, "3160493568"},
{12345678, -8, "48225.3046875"},
{195312, 9, "99999744"},
{1953125, 9, "1000000000"},
} {
var d decimal
d.init(nat{test.x}.norm(), test.shift)
if got := d.String(); got != test.want {
t.Errorf("%d << %d == %s; want %s", test.x, test.shift, got, test.want)
}
}
}
func TestDecimalRounding(t *testing.T) {
for _, test := range []struct {
x uint64
n int
down, even, up string
}{
{0, 0, "0", "0", "0"},
{0, 1, "0", "0", "0"},
{1, 0, "0", "0", "10"},
{5, 0, "0", "0", "10"},
{9, 0, "0", "10", "10"},
{15, 1, "10", "20", "20"},
{45, 1, "40", "40", "50"},
{95, 1, "90", "100", "100"},
{12344999, 4, "12340000", "12340000", "12350000"},
{12345000, 4, "12340000", "12340000", "12350000"},
{12345001, 4, "12340000", "12350000", "12350000"},
{23454999, 4, "23450000", "23450000", "23460000"},
{23455000, 4, "23450000", "23460000", "23460000"},
{23455001, 4, "23450000", "23460000", "23460000"},
{99994999, 4, "99990000", "99990000", "100000000"},
{99995000, 4, "99990000", "100000000", "100000000"},
{99999999, 4, "99990000", "100000000", "100000000"},
{12994999, 4, "12990000", "12990000", "13000000"},
{12995000, 4, "12990000", "13000000", "13000000"},
{12999999, 4, "12990000", "13000000", "13000000"},
} {
x := nat(nil).setUint64(test.x)
var d decimal
d.init(x, 0)
d.roundDown(test.n)
if got := d.String(); got != test.down {
t.Errorf("roundDown(%d, %d) = %s; want %s", test.x, test.n, got, test.down)
}
d.init(x, 0)
d.round(test.n)
if got := d.String(); got != test.even {
t.Errorf("round(%d, %d) = %s; want %s", test.x, test.n, got, test.even)
}
d.init(x, 0)
d.roundUp(test.n)
if got := d.String(); got != test.up {
t.Errorf("roundUp(%d, %d) = %s; want %s", test.x, test.n, got, test.up)
}
}
}
var sink string
func BenchmarkDecimalConversion(b *testing.B) {
for i := 0; i < b.N; i++ {
for shift := -100; shift <= +100; shift++ {
var d decimal
d.init(natOne, shift)
sink = d.String()
}
}
}

99
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
/*
Package big implements arbitrary-precision arithmetic (big numbers).
The following numeric types are supported:
Int signed integers
Rat rational numbers
Float floating-point numbers
The zero value for an Int, Rat, or Float correspond to 0. Thus, new
values can be declared in the usual ways and denote 0 without further
initialization:
var x Int // &x is an *Int of value 0
var r = &Rat{} // r is a *Rat of value 0
y := new(Float) // y is a *Float of value 0
Alternatively, new values can be allocated and initialized with factory
functions of the form:
func NewT(v V) *T
For instance, NewInt(x) returns an *Int set to the value of the int64
argument x, NewRat(a, b) returns a *Rat set to the fraction a/b where
a and b are int64 values, and NewFloat(f) returns a *Float initialized
to the float64 argument f. More flexibility is provided with explicit
setters, for instance:
var z1 Int
z1.SetUint64(123) // z1 := 123
z2 := new(Rat).SetFloat64(1.2) // z2 := 6/5
z3 := new(Float).SetInt(z1) // z3 := 123.0
Setters, numeric operations and predicates are represented as methods of
the form:
func (z *T) SetV(v V) *T // z = v
func (z *T) Unary(x *T) *T // z = unary x
func (z *T) Binary(x, y *T) *T // z = x binary y
func (x *T) Pred() P // p = pred(x)
with T one of Int, Rat, or Float. For unary and binary operations, the
result is the receiver (usually named z in that case; see below); if it
is one of the operands x or y it may be safely overwritten (and its memory
reused).
Arithmetic expressions are typically written as a sequence of individual
method calls, with each call corresponding to an operation. The receiver
denotes the result and the method arguments are the operation's operands.
For instance, given three *Int values a, b and c, the invocation
c.Add(a, b)
computes the sum a + b and stores the result in c, overwriting whatever
value was held in c before. Unless specified otherwise, operations permit
aliasing of parameters, so it is perfectly ok to write
sum.Add(sum, x)
to accumulate values x in a sum.
(By always passing in a result value via the receiver, memory use can be
much better controlled. Instead of having to allocate new memory for each
result, an operation can reuse the space allocated for the result value,
and overwrite that value with the new result in the process.)
Notational convention: Incoming method parameters (including the receiver)
are named consistently in the API to clarify their use. Incoming operands
are usually named x, y, a, b, and so on, but never z. A parameter specifying
the result is named z (typically the receiver).
For instance, the arguments for (*Int).Add are named x and y, and because
the receiver specifies the result destination, it is called z:
func (z *Int) Add(x, y *Int) *Int
Methods of this form typically return the incoming receiver as well, to
enable simple call chaining.
Methods which don't require a result value to be passed in (for instance,
Int.Sign), simply return the result. In this case, the receiver is typically
the first operand, named x:
func (x *Int) Sign() int
Various methods support conversions between strings and corresponding
numeric values, and vice versa: *Int, *Rat, and *Float values implement
the Stringer interface for a (default) string representation of the value,
but also provide SetString methods to initialize a value from a string in
a variety of supported formats (see the respective SetString documentation).
Finally, *Int, *Rat, and *Float satisfy the fmt package's Scanner interface
for scanning and (except for *Rat) the Formatter interface for formatted
printing.
*/
package big

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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big_test
import (
"cmd/compile/internal/big"
"fmt"
)
// Use the classic continued fraction for e
// e = [1; 0, 1, 1, 2, 1, 1, ... 2n, 1, 1, ...]
// i.e., for the nth term, use
// 1 if n mod 3 != 1
// (n-1)/3 * 2 if n mod 3 == 1
func recur(n, lim int64) *big.Rat {
term := new(big.Rat)
if n%3 != 1 {
term.SetInt64(1)
} else {
term.SetInt64((n - 1) / 3 * 2)
}
if n > lim {
return term
}
// Directly initialize frac as the fractional
// inverse of the result of recur.
frac := new(big.Rat).Inv(recur(n+1, lim))
return term.Add(term, frac)
}
// This example demonstrates how to use big.Rat to compute the
// first 15 terms in the sequence of rational convergents for
// the constant e (base of natural logarithm).
func Example_eConvergents() {
for i := 1; i <= 15; i++ {
r := recur(0, int64(i))
// Print r both as a fraction and as a floating-point number.
// Since big.Rat implements fmt.Formatter, we can use %-13s to
// get a left-aligned string representation of the fraction.
fmt.Printf("%-13s = %s\n", r, r.FloatString(8))
}
// Output:
// 2/1 = 2.00000000
// 3/1 = 3.00000000
// 8/3 = 2.66666667
// 11/4 = 2.75000000
// 19/7 = 2.71428571
// 87/32 = 2.71875000
// 106/39 = 2.71794872
// 193/71 = 2.71830986
// 1264/465 = 2.71827957
// 1457/536 = 2.71828358
// 2721/1001 = 2.71828172
// 23225/8544 = 2.71828184
// 25946/9545 = 2.71828182
// 49171/18089 = 2.71828183
// 517656/190435 = 2.71828183
}

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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big_test
import (
"cmd/compile/internal/big"
"fmt"
"log"
"math"
)
func ExampleRat_SetString() {
r := new(big.Rat)
r.SetString("355/113")
fmt.Println(r.FloatString(3))
// Output: 3.142
}
func ExampleInt_SetString() {
i := new(big.Int)
i.SetString("644", 8) // octal
fmt.Println(i)
// Output: 420
}
func ExampleRat_Scan() {
// The Scan function is rarely used directly;
// the fmt package recognizes it as an implementation of fmt.Scanner.
r := new(big.Rat)
_, err := fmt.Sscan("1.5000", r)
if err != nil {
log.Println("error scanning value:", err)
} else {
fmt.Println(r)
}
// Output: 3/2
}
func ExampleInt_Scan() {
// The Scan function is rarely used directly;
// the fmt package recognizes it as an implementation of fmt.Scanner.
i := new(big.Int)
_, err := fmt.Sscan("18446744073709551617", i)
if err != nil {
log.Println("error scanning value:", err)
} else {
fmt.Println(i)
}
// Output: 18446744073709551617
}
// This example demonstrates how to use big.Int to compute the smallest
// Fibonacci number with 100 decimal digits and to test whether it is prime.
func Example_fibonacci() {
// Initialize two big ints with the first two numbers in the sequence.
a := big.NewInt(0)
b := big.NewInt(1)
// Initialize limit as 10^99, the smallest integer with 100 digits.
var limit big.Int
limit.Exp(big.NewInt(10), big.NewInt(99), nil)
// Loop while a is smaller than 1e100.
for a.Cmp(&limit) < 0 {
// Compute the next Fibonacci number, storing it in a.
a.Add(a, b)
// Swap a and b so that b is the next number in the sequence.
a, b = b, a
}
fmt.Println(a) // 100-digit Fibonacci number
// Test a for primality.
// (ProbablyPrimes' argument sets the number of Miller-Rabin
// rounds to be performed. 20 is a good value.)
fmt.Println(a.ProbablyPrime(20))
// Output:
// 1344719667586153181419716641724567886890850696275767987106294472017884974410332069524504824747437757
// false
}
// This example shows how to use big.Float to compute the square root of 2 with
// a precision of 200 bits, and how to print the result as a decimal number.
func Example_sqrt2() {
// We'll do computations with 200 bits of precision in the mantissa.
const prec = 200
// Compute the square root of 2 using Newton's Method. We start with
// an initial estimate for sqrt(2), and then iterate:
// x_{n+1} = 1/2 * ( x_n + (2.0 / x_n) )
// Since Newton's Method doubles the number of correct digits at each
// iteration, we need at least log_2(prec) steps.
steps := int(math.Log2(prec))
// Initialize values we need for the computation.
two := new(big.Float).SetPrec(prec).SetInt64(2)
half := new(big.Float).SetPrec(prec).SetFloat64(0.5)
// Use 1 as the initial estimate.
x := new(big.Float).SetPrec(prec).SetInt64(1)
// We use t as a temporary variable. There's no need to set its precision
// since big.Float values with unset (== 0) precision automatically assume
// the largest precision of the arguments when used as the result (receiver)
// of a big.Float operation.
t := new(big.Float)
// Iterate.
for i := 0; i <= steps; i++ {
t.Quo(two, x) // t = 2.0 / x_n
t.Add(x, t) // t = x_n + (2.0 / x_n)
x.Mul(half, t) // x_{n+1} = 0.5 * t
}
// We can use the usual fmt.Printf verbs since big.Float implements fmt.Formatter
fmt.Printf("sqrt(2) = %.50f\n", x)
// Print the error between 2 and x*x.
t.Mul(x, x) // t = x*x
fmt.Printf("error = %e\n", t.Sub(two, t))
// Output:
// sqrt(2) = 1.41421356237309504880168872420969807856967187537695
// error = 0.000000e+00
}

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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements string-to-Float conversion functions.
package big
import (
"fmt"
"io"
"strings"
)
// SetString sets z to the value of s and returns z and a boolean indicating
// success. s must be a floating-point number of the same format as accepted
// by Parse, with base argument 0.
func (z *Float) SetString(s string) (*Float, bool) {
if f, _, err := z.Parse(s, 0); err == nil {
return f, true
}
return nil, false
}
// scan is like Parse but reads the longest possible prefix representing a valid
// floating point number from an io.ByteScanner rather than a string. It serves
// as the implementation of Parse. It does not recognize ±Inf and does not expect
// EOF at the end.
func (z *Float) scan(r io.ByteScanner, base int) (f *Float, b int, err error) {
prec := z.prec
if prec == 0 {
prec = 64
}
// A reasonable value in case of an error.
z.form = zero
// sign
z.neg, err = scanSign(r)
if err != nil {
return
}
// mantissa
var fcount int // fractional digit count; valid if <= 0
z.mant, b, fcount, err = z.mant.scan(r, base, true)
if err != nil {
return
}
// exponent
var exp int64
var ebase int
exp, ebase, err = scanExponent(r, true)
if err != nil {
return
}
// special-case 0
if len(z.mant) == 0 {
z.prec = prec
z.acc = Exact
z.form = zero
f = z
return
}
// len(z.mant) > 0
// The mantissa may have a decimal point (fcount <= 0) and there
// may be a nonzero exponent exp. The decimal point amounts to a
// division by b**(-fcount). An exponent means multiplication by
// ebase**exp. Finally, mantissa normalization (shift left) requires
// a correcting multiplication by 2**(-shiftcount). Multiplications
// are commutative, so we can apply them in any order as long as there
// is no loss of precision. We only have powers of 2 and 10, and
// we split powers of 10 into the product of the same powers of
// 2 and 5. This reduces the size of the multiplication factor
// needed for base-10 exponents.
// normalize mantissa and determine initial exponent contributions
exp2 := int64(len(z.mant))*_W - fnorm(z.mant)
exp5 := int64(0)
// determine binary or decimal exponent contribution of decimal point
if fcount < 0 {
// The mantissa has a "decimal" point ddd.dddd; and
// -fcount is the number of digits to the right of '.'.
// Adjust relevant exponent accordingly.
d := int64(fcount)
switch b {
case 10:
exp5 = d
fallthrough // 10**e == 5**e * 2**e
case 2:
exp2 += d
case 16:
exp2 += d * 4 // hexadecimal digits are 4 bits each
default:
panic("unexpected mantissa base")
}
// fcount consumed - not needed anymore
}
// take actual exponent into account
switch ebase {
case 10:
exp5 += exp
fallthrough
case 2:
exp2 += exp
default:
panic("unexpected exponent base")
}
// exp consumed - not needed anymore
// apply 2**exp2
if MinExp <= exp2 && exp2 <= MaxExp {
z.prec = prec
z.form = finite
z.exp = int32(exp2)
f = z
} else {
err = fmt.Errorf("exponent overflow")
return
}
if exp5 == 0 {
// no decimal exponent contribution
z.round(0)
return
}
// exp5 != 0
// apply 5**exp5
p := new(Float).SetPrec(z.Prec() + 64) // use more bits for p -- TODO(gri) what is the right number?
if exp5 < 0 {
z.Quo(z, p.pow5(uint64(-exp5)))
} else {
z.Mul(z, p.pow5(uint64(exp5)))
}
return
}
// These powers of 5 fit into a uint64.
//
// for p, q := uint64(0), uint64(1); p < q; p, q = q, q*5 {
// fmt.Println(q)
// }
//
var pow5tab = [...]uint64{
1,
5,
25,
125,
625,
3125,
15625,
78125,
390625,
1953125,
9765625,
48828125,
244140625,
1220703125,
6103515625,
30517578125,
152587890625,
762939453125,
3814697265625,
19073486328125,
95367431640625,
476837158203125,
2384185791015625,
11920928955078125,
59604644775390625,
298023223876953125,
1490116119384765625,
7450580596923828125,
}
// pow5 sets z to 5**n and returns z.
// n must not be negative.
func (z *Float) pow5(n uint64) *Float {
const m = uint64(len(pow5tab) - 1)
if n <= m {
return z.SetUint64(pow5tab[n])
}
// n > m
z.SetUint64(pow5tab[m])
n -= m
// use more bits for f than for z
// TODO(gri) what is the right number?
f := new(Float).SetPrec(z.Prec() + 64).SetUint64(5)
for n > 0 {
if n&1 != 0 {
z.Mul(z, f)
}
f.Mul(f, f)
n >>= 1
}
return z
}
// Parse parses s which must contain a text representation of a floating-
// point number with a mantissa in the given conversion base (the exponent
// is always a decimal number), or a string representing an infinite value.
//
// It sets z to the (possibly rounded) value of the corresponding floating-
// point value, and returns z, the actual base b, and an error err, if any.
// If z's precision is 0, it is changed to 64 before rounding takes effect.
// The number must be of the form:
//
// number = [ sign ] [ prefix ] mantissa [ exponent ] | infinity .
// sign = "+" | "-" .
// prefix = "0" ( "x" | "X" | "b" | "B" ) .
// mantissa = digits | digits "." [ digits ] | "." digits .
// exponent = ( "E" | "e" | "p" ) [ sign ] digits .
// digits = digit { digit } .
// digit = "0" ... "9" | "a" ... "z" | "A" ... "Z" .
// infinity = [ sign ] ( "inf" | "Inf" ) .
//
// The base argument must be 0, 2, 10, or 16. Providing an invalid base
// argument will lead to a run-time panic.
//
// For base 0, the number prefix determines the actual base: A prefix of
// "0x" or "0X" selects base 16, and a "0b" or "0B" prefix selects
// base 2; otherwise, the actual base is 10 and no prefix is accepted.
// The octal prefix "0" is not supported (a leading "0" is simply
// considered a "0").
//
// A "p" exponent indicates a binary (rather then decimal) exponent;
// for instance "0x1.fffffffffffffp1023" (using base 0) represents the
// maximum float64 value. For hexadecimal mantissae, the exponent must
// be binary, if present (an "e" or "E" exponent indicator cannot be
// distinguished from a mantissa digit).
//
// The returned *Float f is nil and the value of z is valid but not
// defined if an error is reported.
//
func (z *Float) Parse(s string, base int) (f *Float, b int, err error) {
// scan doesn't handle ±Inf
if len(s) == 3 && (s == "Inf" || s == "inf") {
f = z.SetInf(false)
return
}
if len(s) == 4 && (s[0] == '+' || s[0] == '-') && (s[1:] == "Inf" || s[1:] == "inf") {
f = z.SetInf(s[0] == '-')
return
}
r := strings.NewReader(s)
if f, b, err = z.scan(r, base); err != nil {
return
}
// entire string must have been consumed
if ch, err2 := r.ReadByte(); err2 == nil {
err = fmt.Errorf("expected end of string, found %q", ch)
} else if err2 != io.EOF {
err = err2
}
return
}
// ParseFloat is like f.Parse(s, base) with f set to the given precision
// and rounding mode.
func ParseFloat(s string, base int, prec uint, mode RoundingMode) (f *Float, b int, err error) {
return new(Float).SetPrec(prec).SetMode(mode).Parse(s, base)
}

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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"fmt"
"math"
"strconv"
"testing"
)
func TestFloatSetFloat64String(t *testing.T) {
inf := math.Inf(0)
nan := math.NaN()
for _, test := range []struct {
s string
x float64 // NaNs represent invalid inputs
}{
// basics
{"0", 0},
{"-0", -0},
{"+0", 0},
{"1", 1},
{"-1", -1},
{"+1", 1},
{"1.234", 1.234},
{"-1.234", -1.234},
{"+1.234", 1.234},
{".1", 0.1},
{"1.", 1},
{"+1.", 1},
// various zeros
{"0e100", 0},
{"-0e+100", 0},
{"+0e-100", 0},
{"0E100", 0},
{"-0E+100", 0},
{"+0E-100", 0},
// various decimal exponent formats
{"1.e10", 1e10},
{"1e+10", 1e10},
{"+1e-10", 1e-10},
{"1E10", 1e10},
{"1.E+10", 1e10},
{"+1E-10", 1e-10},
// infinities
{"Inf", inf},
{"+Inf", inf},
{"-Inf", -inf},
{"inf", inf},
{"+inf", inf},
{"-inf", -inf},
// invalid numbers
{"", nan},
{"-", nan},
{"0x", nan},
{"0e", nan},
{"1.2ef", nan},
{"2..3", nan},
{"123..", nan},
{"infinity", nan},
{"foobar", nan},
// misc decimal values
{"3.14159265", 3.14159265},
{"-687436.79457e-245", -687436.79457e-245},
{"-687436.79457E245", -687436.79457e245},
{".0000000000000000000000000000000000000001", 1e-40},
{"+10000000000000000000000000000000000000000e-0", 1e40},
// decimal mantissa, binary exponent
{"0p0", 0},
{"-0p0", -0},
{"1p10", 1 << 10},
{"1p+10", 1 << 10},
{"+1p-10", 1.0 / (1 << 10)},
{"1024p-12", 0.25},
{"-1p10", -1024},
{"1.5p1", 3},
// binary mantissa, decimal exponent
{"0b0", 0},
{"-0b0", -0},
{"0b0e+10", 0},
{"-0b0e-10", -0},
{"0b1010", 10},
{"0B1010E2", 1000},
{"0b.1", 0.5},
{"0b.001", 0.125},
{"0b.001e3", 125},
// binary mantissa, binary exponent
{"0b0p+10", 0},
{"-0b0p-10", -0},
{"0b.1010p4", 10},
{"0b1p-1", 0.5},
{"0b001p-3", 0.125},
{"0b.001p3", 1},
{"0b0.01p2", 1},
// hexadecimal mantissa and exponent
{"0x0", 0},
{"-0x0", -0},
{"0x0p+10", 0},
{"-0x0p-10", -0},
{"0xff", 255},
{"0X.8p1", 1},
{"-0X0.00008p16", -0.5},
{"0x0.0000000000001p-1022", math.SmallestNonzeroFloat64},
{"0x1.fffffffffffffp1023", math.MaxFloat64},
} {
var x Float
x.SetPrec(53)
_, ok := x.SetString(test.s)
if math.IsNaN(test.x) {
// test.s is invalid
if ok {
t.Errorf("%s: want parse error", test.s)
}
continue
}
// test.s is valid
if !ok {
t.Errorf("%s: got parse error", test.s)
continue
}
f, _ := x.Float64()
want := new(Float).SetFloat64(test.x)
if x.Cmp(want) != 0 {
t.Errorf("%s: got %s (%v); want %v", test.s, &x, f, test.x)
}
}
}
func fdiv(a, b float64) float64 { return a / b }
const (
below1e23 = 99999999999999974834176
above1e23 = 100000000000000008388608
)
func TestFloat64Text(t *testing.T) {
for _, test := range []struct {
x float64
format byte
prec int
want string
}{
{0, 'f', 0, "0"},
{math.Copysign(0, -1), 'f', 0, "-0"},
{1, 'f', 0, "1"},
{-1, 'f', 0, "-1"},
{0.001, 'e', 0, "1e-03"},
{0.459, 'e', 0, "5e-01"},
{1.459, 'e', 0, "1e+00"},
{2.459, 'e', 1, "2.5e+00"},
{3.459, 'e', 2, "3.46e+00"},
{4.459, 'e', 3, "4.459e+00"},
{5.459, 'e', 4, "5.4590e+00"},
{0.001, 'f', 0, "0"},
{0.459, 'f', 0, "0"},
{1.459, 'f', 0, "1"},
{2.459, 'f', 1, "2.5"},
{3.459, 'f', 2, "3.46"},
{4.459, 'f', 3, "4.459"},
{5.459, 'f', 4, "5.4590"},
{0, 'b', 0, "0"},
{math.Copysign(0, -1), 'b', 0, "-0"},
{1.0, 'b', 0, "4503599627370496p-52"},
{-1.0, 'b', 0, "-4503599627370496p-52"},
{4503599627370496, 'b', 0, "4503599627370496p+0"},
{0, 'p', 0, "0"},
{math.Copysign(0, -1), 'p', 0, "-0"},
{1024.0, 'p', 0, "0x.8p+11"},
{-1024.0, 'p', 0, "-0x.8p+11"},
// all test cases below from strconv/ftoa_test.go
{1, 'e', 5, "1.00000e+00"},
{1, 'f', 5, "1.00000"},
{1, 'g', 5, "1"},
{1, 'g', -1, "1"},
{20, 'g', -1, "20"},
{1234567.8, 'g', -1, "1.2345678e+06"},
{200000, 'g', -1, "200000"},
{2000000, 'g', -1, "2e+06"},
// g conversion and zero suppression
{400, 'g', 2, "4e+02"},
{40, 'g', 2, "40"},
{4, 'g', 2, "4"},
{.4, 'g', 2, "0.4"},
{.04, 'g', 2, "0.04"},
{.004, 'g', 2, "0.004"},
{.0004, 'g', 2, "0.0004"},
{.00004, 'g', 2, "4e-05"},
{.000004, 'g', 2, "4e-06"},
{0, 'e', 5, "0.00000e+00"},
{0, 'f', 5, "0.00000"},
{0, 'g', 5, "0"},
{0, 'g', -1, "0"},
{-1, 'e', 5, "-1.00000e+00"},
{-1, 'f', 5, "-1.00000"},
{-1, 'g', 5, "-1"},
{-1, 'g', -1, "-1"},
{12, 'e', 5, "1.20000e+01"},
{12, 'f', 5, "12.00000"},
{12, 'g', 5, "12"},
{12, 'g', -1, "12"},
{123456700, 'e', 5, "1.23457e+08"},
{123456700, 'f', 5, "123456700.00000"},
{123456700, 'g', 5, "1.2346e+08"},
{123456700, 'g', -1, "1.234567e+08"},
{1.2345e6, 'e', 5, "1.23450e+06"},
{1.2345e6, 'f', 5, "1234500.00000"},
{1.2345e6, 'g', 5, "1.2345e+06"},
{1e23, 'e', 17, "9.99999999999999916e+22"},
{1e23, 'f', 17, "99999999999999991611392.00000000000000000"},
{1e23, 'g', 17, "9.9999999999999992e+22"},
{1e23, 'e', -1, "1e+23"},
{1e23, 'f', -1, "100000000000000000000000"},
{1e23, 'g', -1, "1e+23"},
{below1e23, 'e', 17, "9.99999999999999748e+22"},
{below1e23, 'f', 17, "99999999999999974834176.00000000000000000"},
{below1e23, 'g', 17, "9.9999999999999975e+22"},
{below1e23, 'e', -1, "9.999999999999997e+22"},
{below1e23, 'f', -1, "99999999999999970000000"},
{below1e23, 'g', -1, "9.999999999999997e+22"},
{above1e23, 'e', 17, "1.00000000000000008e+23"},
{above1e23, 'f', 17, "100000000000000008388608.00000000000000000"},
{above1e23, 'g', 17, "1.0000000000000001e+23"},
{above1e23, 'e', -1, "1.0000000000000001e+23"},
{above1e23, 'f', -1, "100000000000000010000000"},
{above1e23, 'g', -1, "1.0000000000000001e+23"},
{5e-304 / 1e20, 'g', -1, "5e-324"},
{-5e-304 / 1e20, 'g', -1, "-5e-324"},
{fdiv(5e-304, 1e20), 'g', -1, "5e-324"}, // avoid constant arithmetic
{fdiv(-5e-304, 1e20), 'g', -1, "-5e-324"}, // avoid constant arithmetic
{32, 'g', -1, "32"},
{32, 'g', 0, "3e+01"},
{100, 'x', -1, "%x"},
// {math.NaN(), 'g', -1, "NaN"}, // Float doesn't support NaNs
// {-math.NaN(), 'g', -1, "NaN"}, // Float doesn't support NaNs
{math.Inf(0), 'g', -1, "+Inf"},
{math.Inf(-1), 'g', -1, "-Inf"},
{-math.Inf(0), 'g', -1, "-Inf"},
{-1, 'b', -1, "-4503599627370496p-52"},
// fixed bugs
{0.9, 'f', 1, "0.9"},
{0.09, 'f', 1, "0.1"},
{0.0999, 'f', 1, "0.1"},
{0.05, 'f', 1, "0.1"},
{0.05, 'f', 0, "0"},
{0.5, 'f', 1, "0.5"},
{0.5, 'f', 0, "0"},
{1.5, 'f', 0, "2"},
// http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
{2.2250738585072012e-308, 'g', -1, "2.2250738585072014e-308"},
// http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
{2.2250738585072011e-308, 'g', -1, "2.225073858507201e-308"},
// Issue 2625.
{383260575764816448, 'f', 0, "383260575764816448"},
{383260575764816448, 'g', -1, "3.8326057576481645e+17"},
// Issue 15918.
{1, 'f', -10, "1"},
{1, 'f', -11, "1"},
{1, 'f', -12, "1"},
} {
// The test cases are from the strconv package which tests float64 values.
// When formatting values with prec = -1 (shortest representation),
// the actually available mantissa precision matters.
// For denormalized values, that precision is < 53 (SetFloat64 default).
// Compute and set the actual precision explicitly.
f := new(Float).SetPrec(actualPrec(test.x)).SetFloat64(test.x)
got := f.Text(test.format, test.prec)
if got != test.want {
t.Errorf("%v: got %s; want %s", test, got, test.want)
continue
}
if test.format == 'b' && test.x == 0 {
continue // 'b' format in strconv.Float requires knowledge of bias for 0.0
}
if test.format == 'p' {
continue // 'p' format not supported in strconv.Format
}
// verify that Float format matches strconv format
want := strconv.FormatFloat(test.x, test.format, test.prec, 64)
if got != want {
t.Errorf("%v: got %s; want %s (strconv)", test, got, want)
}
}
}
// actualPrec returns the number of actually used mantissa bits.
func actualPrec(x float64) uint {
if bits := math.Float64bits(x); x != 0 && bits&(0x7ff<<52) == 0 {
// x is denormalized
return 64 - nlz64(bits&(1<<52-1))
}
return 53
}
func TestFloatText(t *testing.T) {
for _, test := range []struct {
x string
prec uint
format byte
digits int
want string
}{
{"0", 10, 'f', 0, "0"},
{"-0", 10, 'f', 0, "-0"},
{"1", 10, 'f', 0, "1"},
{"-1", 10, 'f', 0, "-1"},
{"1.459", 100, 'e', 0, "1e+00"},
{"2.459", 100, 'e', 1, "2.5e+00"},
{"3.459", 100, 'e', 2, "3.46e+00"},
{"4.459", 100, 'e', 3, "4.459e+00"},
{"5.459", 100, 'e', 4, "5.4590e+00"},
{"1.459", 100, 'E', 0, "1E+00"},
{"2.459", 100, 'E', 1, "2.5E+00"},
{"3.459", 100, 'E', 2, "3.46E+00"},
{"4.459", 100, 'E', 3, "4.459E+00"},
{"5.459", 100, 'E', 4, "5.4590E+00"},
{"1.459", 100, 'f', 0, "1"},
{"2.459", 100, 'f', 1, "2.5"},
{"3.459", 100, 'f', 2, "3.46"},
{"4.459", 100, 'f', 3, "4.459"},
{"5.459", 100, 'f', 4, "5.4590"},
{"1.459", 100, 'g', 0, "1"},
{"2.459", 100, 'g', 1, "2"},
{"3.459", 100, 'g', 2, "3.5"},
{"4.459", 100, 'g', 3, "4.46"},
{"5.459", 100, 'g', 4, "5.459"},
{"1459", 53, 'g', 0, "1e+03"},
{"2459", 53, 'g', 1, "2e+03"},
{"3459", 53, 'g', 2, "3.5e+03"},
{"4459", 53, 'g', 3, "4.46e+03"},
{"5459", 53, 'g', 4, "5459"},
{"1459", 53, 'G', 0, "1E+03"},
{"2459", 53, 'G', 1, "2E+03"},
{"3459", 53, 'G', 2, "3.5E+03"},
{"4459", 53, 'G', 3, "4.46E+03"},
{"5459", 53, 'G', 4, "5459"},
{"3", 10, 'e', 40, "3.0000000000000000000000000000000000000000e+00"},
{"3", 10, 'f', 40, "3.0000000000000000000000000000000000000000"},
{"3", 10, 'g', 40, "3"},
{"3e40", 100, 'e', 40, "3.0000000000000000000000000000000000000000e+40"},
{"3e40", 100, 'f', 4, "30000000000000000000000000000000000000000.0000"},
{"3e40", 100, 'g', 40, "3e+40"},
// make sure "stupid" exponents don't stall the machine
{"1e1000000", 64, 'p', 0, "0x.88b3a28a05eade3ap+3321929"},
{"1e646456992", 64, 'p', 0, "0x.e883a0c5c8c7c42ap+2147483644"},
{"1e646456993", 64, 'p', 0, "+Inf"},
{"1e1000000000", 64, 'p', 0, "+Inf"},
{"1e-1000000", 64, 'p', 0, "0x.efb4542cc8ca418ap-3321928"},
{"1e-646456993", 64, 'p', 0, "0x.e17c8956983d9d59p-2147483647"},
{"1e-646456994", 64, 'p', 0, "0"},
{"1e-1000000000", 64, 'p', 0, "0"},
// minimum and maximum values
{"1p2147483646", 64, 'p', 0, "0x.8p+2147483647"},
{"0x.8p2147483647", 64, 'p', 0, "0x.8p+2147483647"},
{"0x.8p-2147483647", 64, 'p', 0, "0x.8p-2147483647"},
{"1p-2147483649", 64, 'p', 0, "0x.8p-2147483648"},
// TODO(gri) need tests for actual large Floats
{"0", 53, 'b', 0, "0"},
{"-0", 53, 'b', 0, "-0"},
{"1.0", 53, 'b', 0, "4503599627370496p-52"},
{"-1.0", 53, 'b', 0, "-4503599627370496p-52"},
{"4503599627370496", 53, 'b', 0, "4503599627370496p+0"},
// issue 9939
{"3", 350, 'b', 0, "1720123961992553633708115671476565205597423741876210842803191629540192157066363606052513914832594264915968p-348"},
{"03", 350, 'b', 0, "1720123961992553633708115671476565205597423741876210842803191629540192157066363606052513914832594264915968p-348"},
{"3.", 350, 'b', 0, "1720123961992553633708115671476565205597423741876210842803191629540192157066363606052513914832594264915968p-348"},
{"3.0", 350, 'b', 0, "1720123961992553633708115671476565205597423741876210842803191629540192157066363606052513914832594264915968p-348"},
{"3.00", 350, 'b', 0, "1720123961992553633708115671476565205597423741876210842803191629540192157066363606052513914832594264915968p-348"},
{"3.000", 350, 'b', 0, "1720123961992553633708115671476565205597423741876210842803191629540192157066363606052513914832594264915968p-348"},
{"3", 350, 'p', 0, "0x.cp+2"},
{"03", 350, 'p', 0, "0x.cp+2"},
{"3.", 350, 'p', 0, "0x.cp+2"},
{"3.0", 350, 'p', 0, "0x.cp+2"},
{"3.00", 350, 'p', 0, "0x.cp+2"},
{"3.000", 350, 'p', 0, "0x.cp+2"},
{"0", 64, 'p', 0, "0"},
{"-0", 64, 'p', 0, "-0"},
{"1024.0", 64, 'p', 0, "0x.8p+11"},
{"-1024.0", 64, 'p', 0, "-0x.8p+11"},
// unsupported format
{"3.14", 64, 'x', 0, "%x"},
{"-3.14", 64, 'x', 0, "%x"},
} {
f, _, err := ParseFloat(test.x, 0, test.prec, ToNearestEven)
if err != nil {
t.Errorf("%v: %s", test, err)
continue
}
got := f.Text(test.format, test.digits)
if got != test.want {
t.Errorf("%v: got %s; want %s", test, got, test.want)
}
// compare with strconv.FormatFloat output if possible
// ('p' format is not supported by strconv.FormatFloat,
// and its output for 0.0 prints a biased exponent value
// as in 0p-1074 which makes no sense to emulate here)
if test.prec == 53 && test.format != 'p' && f.Sign() != 0 {
f64, acc := f.Float64()
if acc != Exact {
t.Errorf("%v: expected exact conversion to float64", test)
continue
}
got := strconv.FormatFloat(f64, test.format, test.digits, 64)
if got != test.want {
t.Errorf("%v: got %s; want %s", test, got, test.want)
}
}
}
}
func TestFloatFormat(t *testing.T) {
for _, test := range []struct {
format string
value interface{} // float32, float64, or string (== 512bit *Float)
want string
}{
// from fmt/fmt_test.go
{"%+.3e", 0.0, "+0.000e+00"},
{"%+.3e", 1.0, "+1.000e+00"},
{"%+.3f", -1.0, "-1.000"},
{"%+.3F", -1.0, "-1.000"},
{"%+.3F", float32(-1.0), "-1.000"},
{"%+07.2f", 1.0, "+001.00"},
{"%+07.2f", -1.0, "-001.00"},
{"%+10.2f", +1.0, " +1.00"},
{"%+10.2f", -1.0, " -1.00"},
{"% .3E", -1.0, "-1.000E+00"},
{"% .3e", 1.0, " 1.000e+00"},
{"%+.3g", 0.0, "+0"},
{"%+.3g", 1.0, "+1"},
{"%+.3g", -1.0, "-1"},
{"% .3g", -1.0, "-1"},
{"% .3g", 1.0, " 1"},
{"%b", float32(1.0), "8388608p-23"},
{"%b", 1.0, "4503599627370496p-52"},
// from fmt/fmt_test.go: old test/fmt_test.go
{"%e", 1.0, "1.000000e+00"},
{"%e", 1234.5678e3, "1.234568e+06"},
{"%e", 1234.5678e-8, "1.234568e-05"},
{"%e", -7.0, "-7.000000e+00"},
{"%e", -1e-9, "-1.000000e-09"},
{"%f", 1234.5678e3, "1234567.800000"},
{"%f", 1234.5678e-8, "0.000012"},
{"%f", -7.0, "-7.000000"},
{"%f", -1e-9, "-0.000000"},
{"%g", 1234.5678e3, "1.2345678e+06"},
{"%g", float32(1234.5678e3), "1.2345678e+06"},
{"%g", 1234.5678e-8, "1.2345678e-05"},
{"%g", -7.0, "-7"},
{"%g", -1e-9, "-1e-09"},
{"%g", float32(-1e-9), "-1e-09"},
{"%E", 1.0, "1.000000E+00"},
{"%E", 1234.5678e3, "1.234568E+06"},
{"%E", 1234.5678e-8, "1.234568E-05"},
{"%E", -7.0, "-7.000000E+00"},
{"%E", -1e-9, "-1.000000E-09"},
{"%G", 1234.5678e3, "1.2345678E+06"},
{"%G", float32(1234.5678e3), "1.2345678E+06"},
{"%G", 1234.5678e-8, "1.2345678E-05"},
{"%G", -7.0, "-7"},
{"%G", -1e-9, "-1E-09"},
{"%G", float32(-1e-9), "-1E-09"},
{"%20.6e", 1.2345e3, " 1.234500e+03"},
{"%20.6e", 1.2345e-3, " 1.234500e-03"},
{"%20e", 1.2345e3, " 1.234500e+03"},
{"%20e", 1.2345e-3, " 1.234500e-03"},
{"%20.8e", 1.2345e3, " 1.23450000e+03"},
{"%20f", 1.23456789e3, " 1234.567890"},
{"%20f", 1.23456789e-3, " 0.001235"},
{"%20f", 12345678901.23456789, " 12345678901.234568"},
{"%-20f", 1.23456789e3, "1234.567890 "},
{"%20.8f", 1.23456789e3, " 1234.56789000"},
{"%20.8f", 1.23456789e-3, " 0.00123457"},
{"%g", 1.23456789e3, "1234.56789"},
{"%g", 1.23456789e-3, "0.00123456789"},
{"%g", 1.23456789e20, "1.23456789e+20"},
{"%20e", math.Inf(1), " +Inf"},
{"%-20f", math.Inf(-1), "-Inf "},
// from fmt/fmt_test.go: comparison of padding rules with C printf
{"%.2f", 1.0, "1.00"},
{"%.2f", -1.0, "-1.00"},
{"% .2f", 1.0, " 1.00"},
{"% .2f", -1.0, "-1.00"},
{"%+.2f", 1.0, "+1.00"},
{"%+.2f", -1.0, "-1.00"},
{"%7.2f", 1.0, " 1.00"},
{"%7.2f", -1.0, " -1.00"},
{"% 7.2f", 1.0, " 1.00"},
{"% 7.2f", -1.0, " -1.00"},
{"%+7.2f", 1.0, " +1.00"},
{"%+7.2f", -1.0, " -1.00"},
{"%07.2f", 1.0, "0001.00"},
{"%07.2f", -1.0, "-001.00"},
{"% 07.2f", 1.0, " 001.00"},
{"% 07.2f", -1.0, "-001.00"},
{"%+07.2f", 1.0, "+001.00"},
{"%+07.2f", -1.0, "-001.00"},
// from fmt/fmt_test.go: zero padding does not apply to infinities
{"%020f", math.Inf(-1), " -Inf"},
{"%020f", math.Inf(+1), " +Inf"},
{"% 020f", math.Inf(-1), " -Inf"},
{"% 020f", math.Inf(+1), " Inf"},
{"%+020f", math.Inf(-1), " -Inf"},
{"%+020f", math.Inf(+1), " +Inf"},
{"%20f", -1.0, " -1.000000"},
// handle %v like %g
{"%v", 0.0, "0"},
{"%v", -7.0, "-7"},
{"%v", -1e-9, "-1e-09"},
{"%v", float32(-1e-9), "-1e-09"},
{"%010v", 0.0, "0000000000"},
// *Float cases
{"%.20f", "1e-20", "0.00000000000000000001"},
{"%.20f", "-1e-20", "-0.00000000000000000001"},
{"%30.20f", "-1e-20", " -0.00000000000000000001"},
{"%030.20f", "-1e-20", "-00000000.00000000000000000001"},
{"%030.20f", "+1e-20", "000000000.00000000000000000001"},
{"% 030.20f", "+1e-20", " 00000000.00000000000000000001"},
// erroneous formats
{"%s", 1.0, "%!s(*big.Float=1)"},
} {
value := new(Float)
switch v := test.value.(type) {
case float32:
value.SetPrec(24).SetFloat64(float64(v))
case float64:
value.SetPrec(53).SetFloat64(v)
case string:
value.SetPrec(512).Parse(v, 0)
default:
t.Fatalf("unsupported test value: %v (%T)", v, v)
}
if got := fmt.Sprintf(test.format, value); got != test.want {
t.Errorf("%v: got %q; want %q", test, got, test.want)
}
}
}
func BenchmarkParseFloatSmallExp(b *testing.B) {
for i := 0; i < b.N; i++ {
for _, s := range []string{
"1e0",
"1e-1",
"1e-2",
"1e-3",
"1e-4",
"1e-5",
"1e-10",
"1e-20",
"1e-50",
"1e1",
"1e2",
"1e3",
"1e4",
"1e5",
"1e10",
"1e20",
"1e50",
} {
var x Float
_, _, err := x.Parse(s, 0)
if err != nil {
b.Fatalf("%s: %v", s, err)
}
}
}
}
func BenchmarkParseFloatLargeExp(b *testing.B) {
for i := 0; i < b.N; i++ {
for _, s := range []string{
"1e0",
"1e-10",
"1e-20",
"1e-30",
"1e-40",
"1e-50",
"1e-100",
"1e-500",
"1e-1000",
"1e-5000",
"1e-10000",
"1e10",
"1e20",
"1e30",
"1e40",
"1e50",
"1e100",
"1e500",
"1e1000",
"1e5000",
"1e10000",
} {
var x Float
_, _, err := x.Parse(s, 0)
if err != nil {
b.Fatalf("%s: %v", s, err)
}
}
}
}

141
src/cmd/compile/internal/big/floatexample_test.go
View file

@ -1,141 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big_test
import (
"cmd/compile/internal/big"
"fmt"
"math"
)
func ExampleFloat_Add() {
// Operate on numbers of different precision.
var x, y, z big.Float
x.SetInt64(1000) // x is automatically set to 64bit precision
y.SetFloat64(2.718281828) // y is automatically set to 53bit precision
z.SetPrec(32)
z.Add(&x, &y)
fmt.Printf("x = %.10g (%s, prec = %d, acc = %s)\n", &x, x.Text('p', 0), x.Prec(), x.Acc())
fmt.Printf("y = %.10g (%s, prec = %d, acc = %s)\n", &y, y.Text('p', 0), y.Prec(), y.Acc())
fmt.Printf("z = %.10g (%s, prec = %d, acc = %s)\n", &z, z.Text('p', 0), z.Prec(), z.Acc())
// Output:
// x = 1000 (0x.fap+10, prec = 64, acc = Exact)
// y = 2.718281828 (0x.adf85458248cd8p+2, prec = 53, acc = Exact)
// z = 1002.718282 (0x.faadf854p+10, prec = 32, acc = Below)
}
func ExampleFloat_shift() {
// Implement Float "shift" by modifying the (binary) exponents directly.
for s := -5; s <= 5; s++ {
x := big.NewFloat(0.5)
x.SetMantExp(x, x.MantExp(nil)+s) // shift x by s
fmt.Println(x)
}
// Output:
// 0.015625
// 0.03125
// 0.0625
// 0.125
// 0.25
// 0.5
// 1
// 2
// 4
// 8
// 16
}
func ExampleFloat_Cmp() {
inf := math.Inf(1)
zero := 0.0
operands := []float64{-inf, -1.2, -zero, 0, +1.2, +inf}
fmt.Println(" x y cmp")
fmt.Println("---------------")
for _, x64 := range operands {
x := big.NewFloat(x64)
for _, y64 := range operands {
y := big.NewFloat(y64)
fmt.Printf("%4g %4g %3d\n", x, y, x.Cmp(y))
}
fmt.Println()
}
// Output:
// x y cmp
// ---------------
// -Inf -Inf 0
// -Inf -1.2 -1
// -Inf -0 -1
// -Inf 0 -1
// -Inf 1.2 -1
// -Inf +Inf -1
//
// -1.2 -Inf 1
// -1.2 -1.2 0
// -1.2 -0 -1
// -1.2 0 -1
// -1.2 1.2 -1
// -1.2 +Inf -1
//
// -0 -Inf 1
// -0 -1.2 1
// -0 -0 0
// -0 0 0
// -0 1.2 -1
// -0 +Inf -1
//
// 0 -Inf 1
// 0 -1.2 1
// 0 -0 0
// 0 0 0
// 0 1.2 -1
// 0 +Inf -1
//
// 1.2 -Inf 1
// 1.2 -1.2 1
// 1.2 -0 1
// 1.2 0 1
// 1.2 1.2 0
// 1.2 +Inf -1
//
// +Inf -Inf 1
// +Inf -1.2 1
// +Inf -0 1
// +Inf 0 1
// +Inf 1.2 1
// +Inf +Inf 0
}
func ExampleRoundingMode() {
operands := []float64{2.6, 2.5, 2.1, -2.1, -2.5, -2.6}
fmt.Print(" x")
for mode := big.ToNearestEven; mode <= big.ToPositiveInf; mode++ {
fmt.Printf(" %s", mode)
}
fmt.Println()
for _, f64 := range operands {
fmt.Printf("%4g", f64)
for mode := big.ToNearestEven; mode <= big.ToPositiveInf; mode++ {
// sample operands above require 2 bits to represent mantissa
// set binary precision to 2 to round them to integer values
f := new(big.Float).SetPrec(2).SetMode(mode).SetFloat64(f64)
fmt.Printf(" %*g", len(mode.String()), f)
}
fmt.Println()
}
// Output:
// x ToNearestEven ToNearestAway ToZero AwayFromZero ToNegativeInf ToPositiveInf
// 2.6 3 3 2 3 2 3
// 2.5 2 3 2 3 2 3
// 2.1 2 2 2 3 2 3
// -2.1 -2 -2 -2 -3 -3 -2
// -2.5 -2 -3 -2 -3 -3 -2
// -2.6 -3 -3 -2 -3 -3 -2
}

120
src/cmd/compile/internal/big/floatmarsh.go
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@ -1,120 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements encoding/decoding of Floats.
package big
import (
"encoding/binary"
"fmt"
)
// Gob codec version. Permits backward-compatible changes to the encoding.
const floatGobVersion byte = 1
// GobEncode implements the gob.GobEncoder interface.
// The Float value and all its attributes (precision,
// rounding mode, accuracy) are marshalled.
func (x *Float) GobEncode() ([]byte, error) {
if x == nil {
return nil, nil
}
// determine max. space (bytes) required for encoding
sz := 1 + 1 + 4 // version + mode|acc|form|neg (3+2+2+1bit) + prec
n := 0 // number of mantissa words
if x.form == finite {
// add space for mantissa and exponent
n = int((x.prec + (_W - 1)) / _W) // required mantissa length in words for given precision
// actual mantissa slice could be shorter (trailing 0's) or longer (unused bits):
// - if shorter, only encode the words present
// - if longer, cut off unused words when encoding in bytes
// (in practice, this should never happen since rounding
// takes care of it, but be safe and do it always)
if len(x.mant) < n {
n = len(x.mant)
}
// len(x.mant) >= n
sz += 4 + n*_S // exp + mant
}
buf := make([]byte, sz)
buf[0] = floatGobVersion
b := byte(x.mode&7)<<5 | byte((x.acc+1)&3)<<3 | byte(x.form&3)<<1
if x.neg {
b |= 1
}
buf[1] = b
binary.BigEndian.PutUint32(buf[2:], x.prec)
if x.form == finite {
binary.BigEndian.PutUint32(buf[6:], uint32(x.exp))
x.mant[len(x.mant)-n:].bytes(buf[10:]) // cut off unused trailing words
}
return buf, nil
}
// GobDecode implements the gob.GobDecoder interface.
// The result is rounded per the precision and rounding mode of
// z unless z's precision is 0, in which case z is set exactly
// to the decoded value.
func (z *Float) GobDecode(buf []byte) error {
if len(buf) == 0 {
// Other side sent a nil or default value.
*z = Float{}
return nil
}
if buf[0] != floatGobVersion {
return fmt.Errorf("Float.GobDecode: encoding version %d not supported", buf[0])
}
oldPrec := z.prec
oldMode := z.mode
b := buf[1]
z.mode = RoundingMode((b >> 5) & 7)
z.acc = Accuracy((b>>3)&3) - 1
z.form = form((b >> 1) & 3)
z.neg = b&1 != 0
z.prec = binary.BigEndian.Uint32(buf[2:])
if z.form == finite {
z.exp = int32(binary.BigEndian.Uint32(buf[6:]))
z.mant = z.mant.setBytes(buf[10:])
}
if oldPrec != 0 {
z.mode = oldMode
z.SetPrec(uint(oldPrec))
}
return nil
}
// MarshalText implements the encoding.TextMarshaler interface.
// Only the Float value is marshaled (in full precision), other
// attributes such as precision or accuracy are ignored.
func (x *Float) MarshalText() (text []byte, err error) {
if x == nil {
return []byte("<nil>"), nil
}
var buf []byte
return x.Append(buf, 'g', -1), nil
}
// UnmarshalText implements the encoding.TextUnmarshaler interface.
// The result is rounded per the precision and rounding mode of z.
// If z's precision is 0, it is changed to 64 before rounding takes
// effect.
func (z *Float) UnmarshalText(text []byte) error {
// TODO(gri): get rid of the []byte/string conversion
_, _, err := z.Parse(string(text), 0)
if err != nil {
err = fmt.Errorf("math/big: cannot unmarshal %q into a *big.Float (%v)", text, err)
}
return err
}

136
src/cmd/compile/internal/big/floatmarsh_test.go
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@ -1,136 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"bytes"
"encoding/gob"
"encoding/json"
"io"
"testing"
)
var floatVals = []string{
"0",
"1",
"0.1",
"2.71828",
"1234567890",
"3.14e1234",
"3.14e-1234",
"0.738957395793475734757349579759957975985497e100",
"0.73895739579347546656564656573475734957975995797598589749859834759476745986795497e100",
"inf",
"Inf",
}
func TestFloatGobEncoding(t *testing.T) {
var medium bytes.Buffer
enc := gob.NewEncoder(&medium)
dec := gob.NewDecoder(&medium)
for _, test := range floatVals {
for _, sign := range []string{"", "+", "-"} {
for _, prec := range []uint{0, 1, 2, 10, 53, 64, 100, 1000} {
for _, mode := range []RoundingMode{ToNearestEven, ToNearestAway, ToZero, AwayFromZero, ToNegativeInf, ToPositiveInf} {
medium.Reset() // empty buffer for each test case (in case of failures)
x := sign + test
var tx Float
_, _, err := tx.SetPrec(prec).SetMode(mode).Parse(x, 0)
if err != nil {
t.Errorf("parsing of %s (%dbits, %v) failed (invalid test case): %v", x, prec, mode, err)
continue
}
// If tx was set to prec == 0, tx.Parse(x, 0) assumes precision 64. Correct it.
if prec == 0 {
tx.SetPrec(0)
}
if err := enc.Encode(&tx); err != nil {
t.Errorf("encoding of %v (%dbits, %v) failed: %v", &tx, prec, mode, err)
continue
}
var rx Float
if err := dec.Decode(&rx); err != nil {
t.Errorf("decoding of %v (%dbits, %v) failed: %v", &tx, prec, mode, err)
continue
}
if rx.Cmp(&tx) != 0 {
t.Errorf("transmission of %s failed: got %s want %s", x, rx.String(), tx.String())
continue
}
if rx.Prec() != prec {
t.Errorf("transmission of %s's prec failed: got %d want %d", x, rx.Prec(), prec)
}
if rx.Mode() != mode {
t.Errorf("transmission of %s's mode failed: got %s want %s", x, rx.Mode(), mode)
}
if rx.Acc() != tx.Acc() {
t.Errorf("transmission of %s's accuracy failed: got %s want %s", x, rx.Acc(), tx.Acc())
}
}
}
}
}
}
func TestFloatCorruptGob(t *testing.T) {
var buf bytes.Buffer
tx := NewFloat(4 / 3).SetPrec(1000).SetMode(ToPositiveInf)
if err := gob.NewEncoder(&buf).Encode(tx); err != nil {
t.Fatal(err)
}
b := buf.Bytes()
var rx Float
if err := gob.NewDecoder(bytes.NewReader(b)).Decode(&rx); err != nil {
t.Fatal(err)
}
if err := gob.NewDecoder(bytes.NewReader(b[:10])).Decode(&rx); err != io.ErrUnexpectedEOF {
t.Errorf("got %v want EOF", err)
}
b[1] = 0
if err := gob.NewDecoder(bytes.NewReader(b)).Decode(&rx); err == nil {
t.Fatal("got nil want version error")
}
}
func TestFloatJSONEncoding(t *testing.T) {
for _, test := range floatVals {
for _, sign := range []string{"", "+", "-"} {
for _, prec := range []uint{0, 1, 2, 10, 53, 64, 100, 1000} {
x := sign + test
var tx Float
_, _, err := tx.SetPrec(prec).Parse(x, 0)
if err != nil {
t.Errorf("parsing of %s (prec = %d) failed (invalid test case): %v", x, prec, err)
continue
}
b, err := json.Marshal(&tx)
if err != nil {
t.Errorf("marshaling of %v (prec = %d) failed: %v", &tx, prec, err)
continue
}
var rx Float
rx.SetPrec(prec)
if err := json.Unmarshal(b, &rx); err != nil {
t.Errorf("unmarshaling of %v (prec = %d) failed: %v", &tx, prec, err)
continue
}
if rx.Cmp(&tx) != 0 {
t.Errorf("JSON encoding of %v (prec = %d) failed: got %v want %v", &tx, prec, &rx, &tx)
}
}
}
}
}

459
src/cmd/compile/internal/big/ftoa.go
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@ -1,459 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements Float-to-string conversion functions.
// It is closely following the corresponding implementation
// in strconv/ftoa.go, but modified and simplified for Float.
package big
import (
"bytes"
"fmt"
"strconv"
)
// Text converts the floating-point number x to a string according
// to the given format and precision prec. The format is one of:
//
// 'e' -d.dddde±dd, decimal exponent, at least two (possibly 0) exponent digits
// 'E' -d.ddddE±dd, decimal exponent, at least two (possibly 0) exponent digits
// 'f' -ddddd.dddd, no exponent
// 'g' like 'e' for large exponents, like 'f' otherwise
// 'G' like 'E' for large exponents, like 'f' otherwise
// 'b' -ddddddp±dd, binary exponent
// 'p' -0x.dddp±dd, binary exponent, hexadecimal mantissa
//
// For the binary exponent formats, the mantissa is printed in normalized form:
//
// 'b' decimal integer mantissa using x.Prec() bits, or -0
// 'p' hexadecimal fraction with 0.5 <= 0.mantissa < 1.0, or -0
//
// If format is a different character, Text returns a "%" followed by the
// unrecognized format character.
//
// The precision prec controls the number of digits (excluding the exponent)
// printed by the 'e', 'E', 'f', 'g', and 'G' formats. For 'e', 'E', and 'f'
// it is the number of digits after the decimal point. For 'g' and 'G' it is
// the total number of digits. A negative precision selects the smallest
// number of decimal digits necessary to identify the value x uniquely using
// x.Prec() mantissa bits.
// The prec value is ignored for the 'b' or 'p' format.
func (x *Float) Text(format byte, prec int) string {
cap := 10 // TODO(gri) determine a good/better value here
if prec > 0 {
cap += prec
}
return string(x.Append(make([]byte, 0, cap), format, prec))
}
// String formats x like x.Text('g', 10).
// (String must be called explicitly, Float.Format does not support %s verb.)
func (x *Float) String() string {
return x.Text('g', 10)
}
// Append appends to buf the string form of the floating-point number x,
// as generated by x.Text, and returns the extended buffer.
func (x *Float) Append(buf []byte, fmt byte, prec int) []byte {
// sign
if x.neg {
buf = append(buf, '-')
}
// Inf
if x.form == inf {
if !x.neg {
buf = append(buf, '+')
}
return append(buf, "Inf"...)
}
// pick off easy formats
switch fmt {
case 'b':
return x.fmtB(buf)
case 'p':
return x.fmtP(buf)
}
// Algorithm:
// 1) convert Float to multiprecision decimal
// 2) round to desired precision
// 3) read digits out and format
// 1) convert Float to multiprecision decimal
var d decimal // == 0.0
if x.form == finite {
// x != 0
d.init(x.mant, int(x.exp)-x.mant.bitLen())
}
// 2) round to desired precision
shortest := false
if prec < 0 {
shortest = true
roundShortest(&d, x)
// Precision for shortest representation mode.
switch fmt {
case 'e', 'E':
prec = len(d.mant) - 1
case 'f':
prec = max(len(d.mant)-d.exp, 0)
case 'g', 'G':
prec = len(d.mant)
}
} else {
// round appropriately
switch fmt {
case 'e', 'E':
// one digit before and number of digits after decimal point
d.round(1 + prec)
case 'f':
// number of digits before and after decimal point
d.round(d.exp + prec)
case 'g', 'G':
if prec == 0 {
prec = 1
}
d.round(prec)
}
}
// 3) read digits out and format
switch fmt {
case 'e', 'E':
return fmtE(buf, fmt, prec, d)
case 'f':
return fmtF(buf, prec, d)
case 'g', 'G':
// trim trailing fractional zeros in %e format
eprec := prec
if eprec > len(d.mant) && len(d.mant) >= d.exp {
eprec = len(d.mant)
}
// %e is used if the exponent from the conversion
// is less than -4 or greater than or equal to the precision.
// If precision was the shortest possible, use eprec = 6 for
// this decision.
if shortest {
eprec = 6
}
exp := d.exp - 1
if exp < -4 || exp >= eprec {
if prec > len(d.mant) {
prec = len(d.mant)
}
return fmtE(buf, fmt+'e'-'g', prec-1, d)
}
if prec > d.exp {
prec = len(d.mant)
}
return fmtF(buf, max(prec-d.exp, 0), d)
}
// unknown format
if x.neg {
buf = buf[:len(buf)-1] // sign was added prematurely - remove it again
}
return append(buf, '%', fmt)
}
func roundShortest(d *decimal, x *Float) {
// if the mantissa is zero, the number is zero - stop now
if len(d.mant) == 0 {
return
}
// Approach: All numbers in the interval [x - 1/2ulp, x + 1/2ulp]
// (possibly exclusive) round to x for the given precision of x.
// Compute the lower and upper bound in decimal form and find the
// shortest decimal number d such that lower <= d <= upper.
// TODO(gri) strconv/ftoa.do describes a shortcut in some cases.
// See if we can use it (in adjusted form) here as well.
// 1) Compute normalized mantissa mant and exponent exp for x such
// that the lsb of mant corresponds to 1/2 ulp for the precision of
// x (i.e., for mant we want x.prec + 1 bits).
mant := nat(nil).set(x.mant)
exp := int(x.exp) - mant.bitLen()
s := mant.bitLen() - int(x.prec+1)
switch {
case s < 0:
mant = mant.shl(mant, uint(-s))
case s > 0:
mant = mant.shr(mant, uint(+s))
}
exp += s
// x = mant * 2**exp with lsb(mant) == 1/2 ulp of x.prec
// 2) Compute lower bound by subtracting 1/2 ulp.
var lower decimal
var tmp nat
lower.init(tmp.sub(mant, natOne), exp)
// 3) Compute upper bound by adding 1/2 ulp.
var upper decimal
upper.init(tmp.add(mant, natOne), exp)
// The upper and lower bounds are possible outputs only if
// the original mantissa is even, so that ToNearestEven rounding
// would round to the original mantissa and not the neighbors.
inclusive := mant[0]&2 == 0 // test bit 1 since original mantissa was shifted by 1
// Now we can figure out the minimum number of digits required.
// Walk along until d has distinguished itself from upper and lower.
for i, m := range d.mant {
l := lower.at(i)
u := upper.at(i)
// Okay to round down (truncate) if lower has a different digit
// or if lower is inclusive and is exactly the result of rounding
// down (i.e., and we have reached the final digit of lower).
okdown := l != m || inclusive && i+1 == len(lower.mant)
// Okay to round up if upper has a different digit and either upper
// is inclusive or upper is bigger than the result of rounding up.
okup := m != u && (inclusive || m+1 < u || i+1 < len(upper.mant))
// If it's okay to do either, then round to the nearest one.
// If it's okay to do only one, do it.
switch {
case okdown && okup:
d.round(i + 1)
return
case okdown:
d.roundDown(i + 1)
return
case okup:
d.roundUp(i + 1)
return
}
}
}
// %e: d.ddddde±dd
func fmtE(buf []byte, fmt byte, prec int, d decimal) []byte {
// first digit
ch := byte('0')
if len(d.mant) > 0 {
ch = d.mant[0]
}
buf = append(buf, ch)
// .moredigits
if prec > 0 {
buf = append(buf, '.')
i := 1
m := min(len(d.mant), prec+1)
if i < m {
buf = append(buf, d.mant[i:m]...)
i = m
}
for ; i <= prec; i++ {
buf = append(buf, '0')
}
}
// e±
buf = append(buf, fmt)
var exp int64
if len(d.mant) > 0 {
exp = int64(d.exp) - 1 // -1 because first digit was printed before '.'
}
if exp < 0 {
ch = '-'
exp = -exp
} else {
ch = '+'
}
buf = append(buf, ch)
// dd...d
if exp < 10 {
buf = append(buf, '0') // at least 2 exponent digits
}
return strconv.AppendInt(buf, exp, 10)
}
// %f: ddddddd.ddddd
func fmtF(buf []byte, prec int, d decimal) []byte {
// integer, padded with zeros as needed
if d.exp > 0 {
m := min(len(d.mant), d.exp)
buf = append(buf, d.mant[:m]...)
for ; m < d.exp; m++ {
buf = append(buf, '0')
}
} else {
buf = append(buf, '0')
}
// fraction
if prec > 0 {
buf = append(buf, '.')
for i := 0; i < prec; i++ {
buf = append(buf, d.at(d.exp+i))
}
}
return buf
}
// fmtB appends the string of x in the format mantissa "p" exponent
// with a decimal mantissa and a binary exponent, or 0" if x is zero,
// and returns the extended buffer.
// The mantissa is normalized such that is uses x.Prec() bits in binary
// representation.
// The sign of x is ignored, and x must not be an Inf.
func (x *Float) fmtB(buf []byte) []byte {
if x.form == zero {
return append(buf, '0')
}
if debugFloat && x.form != finite {
panic("non-finite float")
}
// x != 0
// adjust mantissa to use exactly x.prec bits
m := x.mant
switch w := uint32(len(x.mant)) * _W; {
case w < x.prec:
m = nat(nil).shl(m, uint(x.prec-w))
case w > x.prec:
m = nat(nil).shr(m, uint(w-x.prec))
}
buf = append(buf, m.utoa(10)...)
buf = append(buf, 'p')
e := int64(x.exp) - int64(x.prec)
if e >= 0 {
buf = append(buf, '+')
}
return strconv.AppendInt(buf, e, 10)
}
// fmtP appends the string of x in the format "0x." mantissa "p" exponent
// with a hexadecimal mantissa and a binary exponent, or "0" if x is zero,
// and returns the extended buffer.
// The mantissa is normalized such that 0.5 <= 0.mantissa < 1.0.
// The sign of x is ignored, and x must not be an Inf.
func (x *Float) fmtP(buf []byte) []byte {
if x.form == zero {
return append(buf, '0')
}
if debugFloat && x.form != finite {
panic("non-finite float")
}
// x != 0
// remove trailing 0 words early
// (no need to convert to hex 0's and trim later)
m := x.mant
i := 0
for i < len(m) && m[i] == 0 {
i++
}
m = m[i:]
buf = append(buf, "0x."...)
buf = append(buf, bytes.TrimRight(m.utoa(16), "0")...)
buf = append(buf, 'p')
if x.exp >= 0 {
buf = append(buf, '+')
}
return strconv.AppendInt(buf, int64(x.exp), 10)
}
func min(x, y int) int {
if x < y {
return x
}
return y
}
// Format implements fmt.Formatter. It accepts all the regular
// formats for floating-point numbers ('b', 'e', 'E', 'f', 'F',
// 'g', 'G') as well as 'p' and 'v'. See (*Float).Text for the
// interpretation of 'p'. The 'v' format is handled like 'g'.
// Format also supports specification of the minimum precision
// in digits, the output field width, as well as the format flags
// '+' and ' ' for sign control, '0' for space or zero padding,
// and '-' for left or right justification. See the fmt package
// for details.
func (x *Float) Format(s fmt.State, format rune) {
prec, hasPrec := s.Precision()
if !hasPrec {
prec = 6 // default precision for 'e', 'f'
}
switch format {
case 'e', 'E', 'f', 'b', 'p':
// nothing to do
case 'F':
// (*Float).Text doesn't support 'F'; handle like 'f'
format = 'f'
case 'v':
// handle like 'g'
format = 'g'
fallthrough
case 'g', 'G':
if !hasPrec {
prec = -1 // default precision for 'g', 'G'
}
default:
fmt.Fprintf(s, "%%!%c(*big.Float=%s)", format, x.String())
return
}
var buf []byte
buf = x.Append(buf, byte(format), prec)
if len(buf) == 0 {
buf = []byte("?") // should never happen, but don't crash
}
// len(buf) > 0
var sign string
switch {
case buf[0] == '-':
sign = "-"
buf = buf[1:]
case buf[0] == '+':
// +Inf
sign = "+"
if s.Flag(' ') {
sign = " "
}
buf = buf[1:]
case s.Flag('+'):
sign = "+"
case s.Flag(' '):
sign = " "
}
var padding int
if width, hasWidth := s.Width(); hasWidth && width > len(sign)+len(buf) {
padding = width - len(sign) - len(buf)
}
switch {
case s.Flag('0') && !x.IsInf():
// 0-padding on left
writeMultiple(s, sign, 1)
writeMultiple(s, "0", padding)
s.Write(buf)
case s.Flag('-'):
// padding on right
writeMultiple(s, sign, 1)
s.Write(buf)
writeMultiple(s, " ", padding)
default:
// padding on left
writeMultiple(s, " ", padding)
writeMultiple(s, sign, 1)
s.Write(buf)
}
}

61
src/cmd/compile/internal/big/gcd_test.go
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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements a GCD benchmark.
// Usage: go test math/big -test.bench GCD
package big
import (
"math/rand"
"testing"
)
// randInt returns a pseudo-random Int in the range [1<<(size-1), (1<<size) - 1]
func randInt(r *rand.Rand, size uint) *Int {
n := new(Int).Lsh(intOne, size-1)
x := new(Int).Rand(r, n)
return x.Add(x, n) // make sure result > 1<<(size-1)
}
func runGCD(b *testing.B, aSize, bSize uint) {
b.Run("WithoutXY", func(b *testing.B) {
runGCDExt(b, aSize, bSize, false)
})
b.Run("WithXY", func(b *testing.B) {
runGCDExt(b, aSize, bSize, true)
})
}
func runGCDExt(b *testing.B, aSize, bSize uint, calcXY bool) {
b.StopTimer()
var r = rand.New(rand.NewSource(1234))
aa := randInt(r, aSize)
bb := randInt(r, bSize)
var x, y *Int
if calcXY {
x = new(Int)
y = new(Int)
}
b.StartTimer()
for i := 0; i < b.N; i++ {
new(Int).GCD(x, y, aa, bb)
}
}
func BenchmarkGCD10x10(b *testing.B) { runGCD(b, 10, 10) }
func BenchmarkGCD10x100(b *testing.B) { runGCD(b, 10, 100) }
func BenchmarkGCD10x1000(b *testing.B) { runGCD(b, 10, 1000) }
func BenchmarkGCD10x10000(b *testing.B) { runGCD(b, 10, 10000) }
func BenchmarkGCD10x100000(b *testing.B) { runGCD(b, 10, 100000) }
func BenchmarkGCD100x100(b *testing.B) { runGCD(b, 100, 100) }
func BenchmarkGCD100x1000(b *testing.B) { runGCD(b, 100, 1000) }
func BenchmarkGCD100x10000(b *testing.B) { runGCD(b, 100, 10000) }
func BenchmarkGCD100x100000(b *testing.B) { runGCD(b, 100, 100000) }
func BenchmarkGCD1000x1000(b *testing.B) { runGCD(b, 1000, 1000) }
func BenchmarkGCD1000x10000(b *testing.B) { runGCD(b, 1000, 10000) }
func BenchmarkGCD1000x100000(b *testing.B) { runGCD(b, 1000, 100000) }
func BenchmarkGCD10000x10000(b *testing.B) { runGCD(b, 10000, 10000) }
func BenchmarkGCD10000x100000(b *testing.B) { runGCD(b, 10000, 100000) }
func BenchmarkGCD100000x100000(b *testing.B) { runGCD(b, 100000, 100000) }

160
src/cmd/compile/internal/big/hilbert_test.go
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// A little test program and benchmark for rational arithmetics.
// Computes a Hilbert matrix, its inverse, multiplies them
// and verifies that the product is the identity matrix.
package big
import (
"fmt"
"testing"
)
type matrix struct {
n, m int
a []*Rat
}
func (a *matrix) at(i, j int) *Rat {
if !(0 <= i && i < a.n && 0 <= j && j < a.m) {
panic("index out of range")
}
return a.a[i*a.m+j]
}
func (a *matrix) set(i, j int, x *Rat) {
if !(0 <= i && i < a.n && 0 <= j && j < a.m) {
panic("index out of range")
}
a.a[i*a.m+j] = x
}
func newMatrix(n, m int) *matrix {
if !(0 <= n && 0 <= m) {
panic("illegal matrix")
}
a := new(matrix)
a.n = n
a.m = m
a.a = make([]*Rat, n*m)
return a
}
func newUnit(n int) *matrix {
a := newMatrix(n, n)
for i := 0; i < n; i++ {
for j := 0; j < n; j++ {
x := NewRat(0, 1)
if i == j {
x.SetInt64(1)
}
a.set(i, j, x)
}
}
return a
}
func newHilbert(n int) *matrix {
a := newMatrix(n, n)
for i := 0; i < n; i++ {
for j := 0; j < n; j++ {
a.set(i, j, NewRat(1, int64(i+j+1)))
}
}
return a
}
func newInverseHilbert(n int) *matrix {
a := newMatrix(n, n)
for i := 0; i < n; i++ {
for j := 0; j < n; j++ {
x1 := new(Rat).SetInt64(int64(i + j + 1))
x2 := new(Rat).SetInt(new(Int).Binomial(int64(n+i), int64(n-j-1)))
x3 := new(Rat).SetInt(new(Int).Binomial(int64(n+j), int64(n-i-1)))
x4 := new(Rat).SetInt(new(Int).Binomial(int64(i+j), int64(i)))
x1.Mul(x1, x2)
x1.Mul(x1, x3)
x1.Mul(x1, x4)
x1.Mul(x1, x4)
if (i+j)&1 != 0 {
x1.Neg(x1)
}
a.set(i, j, x1)
}
}
return a
}
func (a *matrix) mul(b *matrix) *matrix {
if a.m != b.n {
panic("illegal matrix multiply")
}
c := newMatrix(a.n, b.m)
for i := 0; i < c.n; i++ {
for j := 0; j < c.m; j++ {
x := NewRat(0, 1)
for k := 0; k < a.m; k++ {
x.Add(x, new(Rat).Mul(a.at(i, k), b.at(k, j)))
}
c.set(i, j, x)
}
}
return c
}
func (a *matrix) eql(b *matrix) bool {
if a.n != b.n || a.m != b.m {
return false
}
for i := 0; i < a.n; i++ {
for j := 0; j < a.m; j++ {
if a.at(i, j).Cmp(b.at(i, j)) != 0 {
return false
}
}
}
return true
}
func (a *matrix) String() string {
s := ""
for i := 0; i < a.n; i++ {
for j := 0; j < a.m; j++ {
s += fmt.Sprintf("\t%s", a.at(i, j))
}
s += "\n"
}
return s
}
func doHilbert(t *testing.T, n int) {
a := newHilbert(n)
b := newInverseHilbert(n)
I := newUnit(n)
ab := a.mul(b)
if !ab.eql(I) {
if t == nil {
panic("Hilbert failed")
}
t.Errorf("a = %s\n", a)
t.Errorf("b = %s\n", b)
t.Errorf("a*b = %s\n", ab)
t.Errorf("I = %s\n", I)
}
}
func TestHilbert(t *testing.T) {
doHilbert(t, 10)
}
func BenchmarkHilbert(b *testing.B) {
for i := 0; i < b.N; i++ {
doHilbert(nil, 10)
}
}

934
src/cmd/compile/internal/big/int.go
View file

@ -1,934 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements signed multi-precision integers.
package big
import (
"fmt"
"io"
"math/rand"
"strings"
)
// An Int represents a signed multi-precision integer.
// The zero value for an Int represents the value 0.
type Int struct {
neg bool // sign
abs nat // absolute value of the integer
}
var intOne = &Int{false, natOne}
// Sign returns:
//
// -1 if x < 0
// 0 if x == 0
// +1 if x > 0
//
func (x *Int) Sign() int {
if len(x.abs) == 0 {
return 0
}
if x.neg {
return -1
}
return 1
}
// SetInt64 sets z to x and returns z.
func (z *Int) SetInt64(x int64) *Int {
neg := false
if x < 0 {
neg = true
x = -x
}
z.abs = z.abs.setUint64(uint64(x))
z.neg = neg
return z
}
// SetUint64 sets z to x and returns z.
func (z *Int) SetUint64(x uint64) *Int {
z.abs = z.abs.setUint64(x)
z.neg = false
return z
}
// NewInt allocates and returns a new Int set to x.
func NewInt(x int64) *Int {
return new(Int).SetInt64(x)
}
// Set sets z to x and returns z.
func (z *Int) Set(x *Int) *Int {
if z != x {
z.abs = z.abs.set(x.abs)
z.neg = x.neg
}
return z
}
// Bits provides raw (unchecked but fast) access to x by returning its
// absolute value as a little-endian Word slice. The result and x share
// the same underlying array.
// Bits is intended to support implementation of missing low-level Int
// functionality outside this package; it should be avoided otherwise.
func (x *Int) Bits() []Word {
return x.abs
}
// SetBits provides raw (unchecked but fast) access to z by setting its
// value to abs, interpreted as a little-endian Word slice, and returning
// z. The result and abs share the same underlying array.
// SetBits is intended to support implementation of missing low-level Int
// functionality outside this package; it should be avoided otherwise.
func (z *Int) SetBits(abs []Word) *Int {
z.abs = nat(abs).norm()
z.neg = false
return z
}
// Abs sets z to |x| (the absolute value of x) and returns z.
func (z *Int) Abs(x *Int) *Int {
z.Set(x)
z.neg = false
return z
}
// Neg sets z to -x and returns z.
func (z *Int) Neg(x *Int) *Int {
z.Set(x)
z.neg = len(z.abs) > 0 && !z.neg // 0 has no sign
return z
}
// Add sets z to the sum x+y and returns z.
func (z *Int) Add(x, y *Int) *Int {
neg := x.neg
if x.neg == y.neg {
// x + y == x + y
// (-x) + (-y) == -(x + y)
z.abs = z.abs.add(x.abs, y.abs)
} else {
// x + (-y) == x - y == -(y - x)
// (-x) + y == y - x == -(x - y)
if x.abs.cmp(y.abs) >= 0 {
z.abs = z.abs.sub(x.abs, y.abs)
} else {
neg = !neg
z.abs = z.abs.sub(y.abs, x.abs)
}
}
z.neg = len(z.abs) > 0 && neg // 0 has no sign
return z
}
// Sub sets z to the difference x-y and returns z.
func (z *Int) Sub(x, y *Int) *Int {
neg := x.neg
if x.neg != y.neg {
// x - (-y) == x + y
// (-x) - y == -(x + y)
z.abs = z.abs.add(x.abs, y.abs)
} else {
// x - y == x - y == -(y - x)
// (-x) - (-y) == y - x == -(x - y)
if x.abs.cmp(y.abs) >= 0 {
z.abs = z.abs.sub(x.abs, y.abs)
} else {
neg = !neg
z.abs = z.abs.sub(y.abs, x.abs)
}
}
z.neg = len(z.abs) > 0 && neg // 0 has no sign
return z
}
// Mul sets z to the product x*y and returns z.
func (z *Int) Mul(x, y *Int) *Int {
// x * y == x * y
// x * (-y) == -(x * y)
// (-x) * y == -(x * y)
// (-x) * (-y) == x * y
z.abs = z.abs.mul(x.abs, y.abs)
z.neg = len(z.abs) > 0 && x.neg != y.neg // 0 has no sign
return z
}
// MulRange sets z to the product of all integers
// in the range [a, b] inclusively and returns z.
// If a > b (empty range), the result is 1.
func (z *Int) MulRange(a, b int64) *Int {
switch {
case a > b:
return z.SetInt64(1) // empty range
case a <= 0 && b >= 0:
return z.SetInt64(0) // range includes 0
}
// a <= b && (b < 0 || a > 0)
neg := false
if a < 0 {
neg = (b-a)&1 == 0
a, b = -b, -a
}
z.abs = z.abs.mulRange(uint64(a), uint64(b))
z.neg = neg
return z
}
// Binomial sets z to the binomial coefficient of (n, k) and returns z.
func (z *Int) Binomial(n, k int64) *Int {
// reduce the number of multiplications by reducing k
if n/2 < k && k <= n {
k = n - k // Binomial(n, k) == Binomial(n, n-k)
}
var a, b Int
a.MulRange(n-k+1, n)
b.MulRange(1, k)
return z.Quo(&a, &b)
}
// Quo sets z to the quotient x/y for y != 0 and returns z.
// If y == 0, a division-by-zero run-time panic occurs.
// Quo implements truncated division (like Go); see QuoRem for more details.
func (z *Int) Quo(x, y *Int) *Int {
z.abs, _ = z.abs.div(nil, x.abs, y.abs)
z.neg = len(z.abs) > 0 && x.neg != y.neg // 0 has no sign
return z
}
// Rem sets z to the remainder x%y for y != 0 and returns z.
// If y == 0, a division-by-zero run-time panic occurs.
// Rem implements truncated modulus (like Go); see QuoRem for more details.
func (z *Int) Rem(x, y *Int) *Int {
_, z.abs = nat(nil).div(z.abs, x.abs, y.abs)
z.neg = len(z.abs) > 0 && x.neg // 0 has no sign
return z
}
// QuoRem sets z to the quotient x/y and r to the remainder x%y
// and returns the pair (z, r) for y != 0.
// If y == 0, a division-by-zero run-time panic occurs.
//
// QuoRem implements T-division and modulus (like Go):
//
// q = x/y with the result truncated to zero
// r = x - y*q
//
// (See Daan Leijen, ``Division and Modulus for Computer Scientists''.)
// See DivMod for Euclidean division and modulus (unlike Go).
//
func (z *Int) QuoRem(x, y, r *Int) (*Int, *Int) {
z.abs, r.abs = z.abs.div(r.abs, x.abs, y.abs)
z.neg, r.neg = len(z.abs) > 0 && x.neg != y.neg, len(r.abs) > 0 && x.neg // 0 has no sign
return z, r
}
// Div sets z to the quotient x/y for y != 0 and returns z.
// If y == 0, a division-by-zero run-time panic occurs.
// Div implements Euclidean division (unlike Go); see DivMod for more details.
func (z *Int) Div(x, y *Int) *Int {
y_neg := y.neg // z may be an alias for y
var r Int
z.QuoRem(x, y, &r)
if r.neg {
if y_neg {
z.Add(z, intOne)
} else {
z.Sub(z, intOne)
}
}
return z
}
// Mod sets z to the modulus x%y for y != 0 and returns z.
// If y == 0, a division-by-zero run-time panic occurs.
// Mod implements Euclidean modulus (unlike Go); see DivMod for more details.
func (z *Int) Mod(x, y *Int) *Int {
y0 := y // save y
if z == y || alias(z.abs, y.abs) {
y0 = new(Int).Set(y)
}
var q Int
q.QuoRem(x, y, z)
if z.neg {
if y0.neg {
z.Sub(z, y0)
} else {
z.Add(z, y0)
}
}
return z
}
// DivMod sets z to the quotient x div y and m to the modulus x mod y
// and returns the pair (z, m) for y != 0.
// If y == 0, a division-by-zero run-time panic occurs.
//
// DivMod implements Euclidean division and modulus (unlike Go):
//
// q = x div y such that
// m = x - y*q with 0 <= m < |y|
//
// (See Raymond T. Boute, ``The Euclidean definition of the functions
// div and mod''. ACM Transactions on Programming Languages and
// Systems (TOPLAS), 14(2):127-144, New York, NY, USA, 4/1992.
// ACM press.)
// See QuoRem for T-division and modulus (like Go).
//
func (z *Int) DivMod(x, y, m *Int) (*Int, *Int) {
y0 := y // save y
if z == y || alias(z.abs, y.abs) {
y0 = new(Int).Set(y)
}
z.QuoRem(x, y, m)
if m.neg {
if y0.neg {
z.Add(z, intOne)
m.Sub(m, y0)
} else {
z.Sub(z, intOne)
m.Add(m, y0)
}
}
return z, m
}
// Cmp compares x and y and returns:
//
// -1 if x < y
// 0 if x == y
// +1 if x > y
//
func (x *Int) Cmp(y *Int) (r int) {
// x cmp y == x cmp y
// x cmp (-y) == x
// (-x) cmp y == y
// (-x) cmp (-y) == -(x cmp y)
switch {
case x.neg == y.neg:
r = x.abs.cmp(y.abs)
if x.neg {
r = -r
}
case x.neg:
r = -1
default:
r = 1
}
return
}
// low32 returns the least significant 32 bits of z.
func low32(z nat) uint32 {
if len(z) == 0 {
return 0
}
return uint32(z[0])
}
// low64 returns the least significant 64 bits of z.
func low64(z nat) uint64 {
if len(z) == 0 {
return 0
}
v := uint64(z[0])
if _W == 32 && len(z) > 1 {
v |= uint64(z[1]) << 32
}
return v
}
// Int64 returns the int64 representation of x.
// If x cannot be represented in an int64, the result is undefined.
func (x *Int) Int64() int64 {
v := int64(low64(x.abs))
if x.neg {
v = -v
}
return v
}
// Uint64 returns the uint64 representation of x.
// If x cannot be represented in a uint64, the result is undefined.
func (x *Int) Uint64() uint64 {
return low64(x.abs)
}
// SetString sets z to the value of s, interpreted in the given base,
// and returns z and a boolean indicating success. If SetString fails,
// the value of z is undefined but the returned value is nil.
//
// The base argument must be 0 or a value between 2 and MaxBase. If the base
// is 0, the string prefix determines the actual conversion base. A prefix of
// ``0x'' or ``0X'' selects base 16; the ``0'' prefix selects base 8, and a
// ``0b'' or ``0B'' prefix selects base 2. Otherwise the selected base is 10.
//
func (z *Int) SetString(s string, base int) (*Int, bool) {
r := strings.NewReader(s)
_, _, err := z.scan(r, base)
if err != nil {
return nil, false
}
_, err = r.ReadByte()
if err != io.EOF {
return nil, false
}
return z, true // err == io.EOF => scan consumed all of s
}
// SetBytes interprets buf as the bytes of a big-endian unsigned
// integer, sets z to that value, and returns z.
func (z *Int) SetBytes(buf []byte) *Int {
z.abs = z.abs.setBytes(buf)
z.neg = false
return z
}
// Bytes returns the absolute value of x as a big-endian byte slice.
func (x *Int) Bytes() []byte {
buf := make([]byte, len(x.abs)*_S)
return buf[x.abs.bytes(buf):]
}
// BitLen returns the length of the absolute value of x in bits.
// The bit length of 0 is 0.
func (x *Int) BitLen() int {
return x.abs.bitLen()
}
// Exp sets z = x**y mod |m| (i.e. the sign of m is ignored), and returns z.
// If y <= 0, the result is 1 mod |m|; if m == nil or m == 0, z = x**y.
// See Knuth, volume 2, section 4.6.3.
func (z *Int) Exp(x, y, m *Int) *Int {
var yWords nat
if !y.neg {
yWords = y.abs
}
// y >= 0
var mWords nat
if m != nil {
mWords = m.abs // m.abs may be nil for m == 0
}
z.abs = z.abs.expNN(x.abs, yWords, mWords)
z.neg = len(z.abs) > 0 && x.neg && len(yWords) > 0 && yWords[0]&1 == 1 // 0 has no sign
if z.neg && len(mWords) > 0 {
// make modulus result positive
z.abs = z.abs.sub(mWords, z.abs) // z == x**y mod |m| && 0 <= z < |m|
z.neg = false
}
return z
}
// GCD sets z to the greatest common divisor of a and b, which both must
// be > 0, and returns z.
// If x and y are not nil, GCD sets x and y such that z = a*x + b*y.
// If either a or b is <= 0, GCD sets z = x = y = 0.
func (z *Int) GCD(x, y, a, b *Int) *Int {
if a.Sign() <= 0 || b.Sign() <= 0 {
z.SetInt64(0)
if x != nil {
x.SetInt64(0)
}
if y != nil {
y.SetInt64(0)
}
return z
}
if x == nil && y == nil {
return z.binaryGCD(a, b)
}
A := new(Int).Set(a)
B := new(Int).Set(b)
X := new(Int)
Y := new(Int).SetInt64(1)
lastX := new(Int).SetInt64(1)
lastY := new(Int)
q := new(Int)
temp := new(Int)
r := new(Int)
for len(B.abs) > 0 {
q, r = q.QuoRem(A, B, r)
A, B, r = B, r, A
temp.Set(X)
X.Mul(X, q)
X.neg = !X.neg
X.Add(X, lastX)
lastX.Set(temp)
temp.Set(Y)
Y.Mul(Y, q)
Y.neg = !Y.neg
Y.Add(Y, lastY)
lastY.Set(temp)
}
if x != nil {
*x = *lastX
}
if y != nil {
*y = *lastY
}
*z = *A
return z
}
// binaryGCD sets z to the greatest common divisor of a and b, which both must
// be > 0, and returns z.
// See Knuth, The Art of Computer Programming, Vol. 2, Section 4.5.2, Algorithm B.
func (z *Int) binaryGCD(a, b *Int) *Int {
u := z
v := new(Int)
// use one Euclidean iteration to ensure that u and v are approx. the same size
switch {
case len(a.abs) > len(b.abs):
// must set v before u since u may be alias for a or b (was issue #11284)
v.Rem(a, b)
u.Set(b)
case len(a.abs) < len(b.abs):
v.Rem(b, a)
u.Set(a)
default:
v.Set(b)
u.Set(a)
}
// a, b must not be used anymore (may be aliases with u)
// v might be 0 now
if len(v.abs) == 0 {
return u
}
// u > 0 && v > 0
// determine largest k such that u = u' << k, v = v' << k
k := u.abs.trailingZeroBits()
if vk := v.abs.trailingZeroBits(); vk < k {
k = vk
}
u.Rsh(u, k)
v.Rsh(v, k)
// determine t (we know that u > 0)
t := new(Int)
if u.abs[0]&1 != 0 {
// u is odd
t.Neg(v)
} else {
t.Set(u)
}
for len(t.abs) > 0 {
// reduce t
t.Rsh(t, t.abs.trailingZeroBits())
if t.neg {
v, t = t, v
v.neg = len(v.abs) > 0 && !v.neg // 0 has no sign
} else {
u, t = t, u
}
t.Sub(u, v)
}
return z.Lsh(u, k)
}
// ProbablyPrime performs n Miller-Rabin tests to check whether x is prime.
// If x is prime, it returns true.
// If x is not prime, it returns false with probability at least 1 - ¼ⁿ.
//
// It is not suitable for judging primes that an adversary may have crafted
// to fool this test.
func (x *Int) ProbablyPrime(n int) bool {
if n <= 0 {
panic("non-positive n for ProbablyPrime")
}
return !x.neg && x.abs.probablyPrime(n)
}
// Rand sets z to a pseudo-random number in [0, n) and returns z.
func (z *Int) Rand(rnd *rand.Rand, n *Int) *Int {
z.neg = false
if n.neg == true || len(n.abs) == 0 {
z.abs = nil
return z
}
z.abs = z.abs.random(rnd, n.abs, n.abs.bitLen())
return z
}
// ModInverse sets z to the multiplicative inverse of g in the ring ℤ/nℤ
// and returns z. If g and n are not relatively prime, the result is undefined.
func (z *Int) ModInverse(g, n *Int) *Int {
var d Int
d.GCD(z, nil, g, n)
// x and y are such that g*x + n*y = d. Since g and n are
// relatively prime, d = 1. Taking that modulo n results in
// g*x = 1, therefore x is the inverse element.
if z.neg {
z.Add(z, n)
}
return z
}
// Jacobi returns the Jacobi symbol (x/y), either +1, -1, or 0.
// The y argument must be an odd integer.
func Jacobi(x, y *Int) int {
if len(y.abs) == 0 || y.abs[0]&1 == 0 {
panic(fmt.Sprintf("big: invalid 2nd argument to Int.Jacobi: need odd integer but got %s", y))
}
// We use the formulation described in chapter 2, section 2.4,
// "The Yacas Book of Algorithms":
// http://yacas.sourceforge.net/Algo.book.pdf
var a, b, c Int
a.Set(x)
b.Set(y)
j := 1
if b.neg {
if a.neg {
j = -1
}
b.neg = false
}
for {
if b.Cmp(intOne) == 0 {
return j
}
if len(a.abs) == 0 {
return 0
}
a.Mod(&a, &b)
if len(a.abs) == 0 {
return 0
}
// a > 0
// handle factors of 2 in 'a'
s := a.abs.trailingZeroBits()
if s&1 != 0 {
bmod8 := b.abs[0] & 7
if bmod8 == 3 || bmod8 == 5 {
j = -j
}
}
c.Rsh(&a, s) // a = 2^s*c
// swap numerator and denominator
if b.abs[0]&3 == 3 && c.abs[0]&3 == 3 {
j = -j
}
a.Set(&b)
b.Set(&c)
}
}
// modSqrt3Mod4 uses the identity
// (a^((p+1)/4))^2 mod p
// == u^(p+1) mod p
// == u^2 mod p
// to calculate the square root of any quadratic residue mod p quickly for 3
// mod 4 primes.
func (z *Int) modSqrt3Mod4Prime(x, p *Int) *Int {
z.Set(p) // z = p
z.Add(z, intOne) // z = p + 1
z.Rsh(z, 2) // z = (p + 1) / 4
z.Exp(x, z, p) // z = x^z mod p
return z
}
// modSqrtTonelliShanks uses the Tonelli-Shanks algorithm to find the square
// root of a quadratic residue modulo any prime.
func (z *Int) modSqrtTonelliShanks(x, p *Int) *Int {
// Break p-1 into s*2^e such that s is odd.
var s Int
s.Sub(p, intOne)
e := s.abs.trailingZeroBits()
s.Rsh(&s, e)
// find some non-square n
var n Int
n.SetInt64(2)
for Jacobi(&n, p) != -1 {
n.Add(&n, intOne)
}
// Core of the Tonelli-Shanks algorithm. Follows the description in
// section 6 of "Square roots from 1; 24, 51, 10 to Dan Shanks" by Ezra
// Brown:
// https://www.maa.org/sites/default/files/pdf/upload_library/22/Polya/07468342.di020786.02p0470a.pdf
var y, b, g, t Int
y.Add(&s, intOne)
y.Rsh(&y, 1)
y.Exp(x, &y, p) // y = x^((s+1)/2)
b.Exp(x, &s, p) // b = x^s
g.Exp(&n, &s, p) // g = n^s
r := e
for {
// find the least m such that ord_p(b) = 2^m
var m uint
t.Set(&b)
for t.Cmp(intOne) != 0 {
t.Mul(&t, &t).Mod(&t, p)
m++
}
if m == 0 {
return z.Set(&y)
}
t.SetInt64(0).SetBit(&t, int(r-m-1), 1).Exp(&g, &t, p)
// t = g^(2^(r-m-1)) mod p
g.Mul(&t, &t).Mod(&g, p) // g = g^(2^(r-m)) mod p
y.Mul(&y, &t).Mod(&y, p)
b.Mul(&b, &g).Mod(&b, p)
r = m
}
}
// ModSqrt sets z to a square root of x mod p if such a square root exists, and
// returns z. The modulus p must be an odd prime. If x is not a square mod p,
// ModSqrt leaves z unchanged and returns nil. This function panics if p is
// not an odd integer.
func (z *Int) ModSqrt(x, p *Int) *Int {
switch Jacobi(x, p) {
case -1:
return nil // x is not a square mod p
case 0:
return z.SetInt64(0) // sqrt(0) mod p = 0
case 1:
break
}
if x.neg || x.Cmp(p) >= 0 { // ensure 0 <= x < p
x = new(Int).Mod(x, p)
}
// Check whether p is 3 mod 4, and if so, use the faster algorithm.
if len(p.abs) > 0 && p.abs[0]%4 == 3 {
return z.modSqrt3Mod4Prime(x, p)
}
// Otherwise, use Tonelli-Shanks.
return z.modSqrtTonelliShanks(x, p)
}
// Lsh sets z = x << n and returns z.
func (z *Int) Lsh(x *Int, n uint) *Int {
z.abs = z.abs.shl(x.abs, n)
z.neg = x.neg
return z
}
// Rsh sets z = x >> n and returns z.
func (z *Int) Rsh(x *Int, n uint) *Int {
if x.neg {
// (-x) >> s == ^(x-1) >> s == ^((x-1) >> s) == -(((x-1) >> s) + 1)
t := z.abs.sub(x.abs, natOne) // no underflow because |x| > 0
t = t.shr(t, n)
z.abs = t.add(t, natOne)
z.neg = true // z cannot be zero if x is negative
return z
}
z.abs = z.abs.shr(x.abs, n)
z.neg = false
return z
}
// Bit returns the value of the i'th bit of x. That is, it
// returns (x>>i)&1. The bit index i must be >= 0.
func (x *Int) Bit(i int) uint {
if i == 0 {
// optimization for common case: odd/even test of x
if len(x.abs) > 0 {
return uint(x.abs[0] & 1) // bit 0 is same for -x
}
return 0
}
if i < 0 {
panic("negative bit index")
}
if x.neg {
t := nat(nil).sub(x.abs, natOne)
return t.bit(uint(i)) ^ 1
}
return x.abs.bit(uint(i))
}
// SetBit sets z to x, with x's i'th bit set to b (0 or 1).
// That is, if b is 1 SetBit sets z = x | (1 << i);
// if b is 0 SetBit sets z = x &^ (1 << i). If b is not 0 or 1,
// SetBit will panic.
func (z *Int) SetBit(x *Int, i int, b uint) *Int {
if i < 0 {
panic("negative bit index")
}
if x.neg {
t := z.abs.sub(x.abs, natOne)
t = t.setBit(t, uint(i), b^1)
z.abs = t.add(t, natOne)
z.neg = len(z.abs) > 0
return z
}
z.abs = z.abs.setBit(x.abs, uint(i), b)
z.neg = false
return z
}
// And sets z = x & y and returns z.
func (z *Int) And(x, y *Int) *Int {
if x.neg == y.neg {
if x.neg {
// (-x) & (-y) == ^(x-1) & ^(y-1) == ^((x-1) | (y-1)) == -(((x-1) | (y-1)) + 1)
x1 := nat(nil).sub(x.abs, natOne)
y1 := nat(nil).sub(y.abs, natOne)
z.abs = z.abs.add(z.abs.or(x1, y1), natOne)
z.neg = true // z cannot be zero if x and y are negative
return z
}
// x & y == x & y
z.abs = z.abs.and(x.abs, y.abs)
z.neg = false
return z
}
// x.neg != y.neg
if x.neg {
x, y = y, x // & is symmetric
}
// x & (-y) == x & ^(y-1) == x &^ (y-1)
y1 := nat(nil).sub(y.abs, natOne)
z.abs = z.abs.andNot(x.abs, y1)
z.neg = false
return z
}
// AndNot sets z = x &^ y and returns z.
func (z *Int) AndNot(x, y *Int) *Int {
if x.neg == y.neg {
if x.neg {
// (-x) &^ (-y) == ^(x-1) &^ ^(y-1) == ^(x-1) & (y-1) == (y-1) &^ (x-1)
x1 := nat(nil).sub(x.abs, natOne)
y1 := nat(nil).sub(y.abs, natOne)
z.abs = z.abs.andNot(y1, x1)
z.neg = false
return z
}
// x &^ y == x &^ y
z.abs = z.abs.andNot(x.abs, y.abs)
z.neg = false
return z
}
if x.neg {
// (-x) &^ y == ^(x-1) &^ y == ^(x-1) & ^y == ^((x-1) | y) == -(((x-1) | y) + 1)
x1 := nat(nil).sub(x.abs, natOne)
z.abs = z.abs.add(z.abs.or(x1, y.abs), natOne)
z.neg = true // z cannot be zero if x is negative and y is positive
return z
}
// x &^ (-y) == x &^ ^(y-1) == x & (y-1)
y1 := nat(nil).sub(y.abs, natOne)
z.abs = z.abs.and(x.abs, y1)
z.neg = false
return z
}
// Or sets z = x | y and returns z.
func (z *Int) Or(x, y *Int) *Int {
if x.neg == y.neg {
if x.neg {
// (-x) | (-y) == ^(x-1) | ^(y-1) == ^((x-1) & (y-1)) == -(((x-1) & (y-1)) + 1)
x1 := nat(nil).sub(x.abs, natOne)
y1 := nat(nil).sub(y.abs, natOne)
z.abs = z.abs.add(z.abs.and(x1, y1), natOne)
z.neg = true // z cannot be zero if x and y are negative
return z
}
// x | y == x | y
z.abs = z.abs.or(x.abs, y.abs)
z.neg = false
return z
}
// x.neg != y.neg
if x.neg {
x, y = y, x // | is symmetric
}
// x | (-y) == x | ^(y-1) == ^((y-1) &^ x) == -(^((y-1) &^ x) + 1)
y1 := nat(nil).sub(y.abs, natOne)
z.abs = z.abs.add(z.abs.andNot(y1, x.abs), natOne)
z.neg = true // z cannot be zero if one of x or y is negative
return z
}
// Xor sets z = x ^ y and returns z.
func (z *Int) Xor(x, y *Int) *Int {
if x.neg == y.neg {
if x.neg {
// (-x) ^ (-y) == ^(x-1) ^ ^(y-1) == (x-1) ^ (y-1)
x1 := nat(nil).sub(x.abs, natOne)
y1 := nat(nil).sub(y.abs, natOne)
z.abs = z.abs.xor(x1, y1)
z.neg = false
return z
}
// x ^ y == x ^ y
z.abs = z.abs.xor(x.abs, y.abs)
z.neg = false
return z
}
// x.neg != y.neg
if x.neg {
x, y = y, x // ^ is symmetric
}
// x ^ (-y) == x ^ ^(y-1) == ^(x ^ (y-1)) == -((x ^ (y-1)) + 1)
y1 := nat(nil).sub(y.abs, natOne)
z.abs = z.abs.add(z.abs.xor(x.abs, y1), natOne)
z.neg = true // z cannot be zero if only one of x or y is negative
return z
}
// Not sets z = ^x and returns z.
func (z *Int) Not(x *Int) *Int {
if x.neg {
// ^(-x) == ^(^(x-1)) == x-1
z.abs = z.abs.sub(x.abs, natOne)
z.neg = false
return z
}
// ^x == -x-1 == -(x+1)
z.abs = z.abs.add(x.abs, natOne)
z.neg = true // z cannot be zero if x is positive
return z
}

1482
src/cmd/compile/internal/big/int_test.go
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248
src/cmd/compile/internal/big/intconv.go
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@ -1,248 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements int-to-string conversion functions.
package big
import (
"errors"
"fmt"
"io"
)
// TODO(gri) Should rename itoa to utoa (there's no sign). That
// would permit the introduction of itoa which is like utoa but
// reserves a byte for a possible sign that's passed in. That
// would permit Int.Text to be implemented w/o the need for
// string copy if the number is negative.
// Text returns the string representation of x in the given base.
// Base must be between 2 and 36, inclusive. The result uses the
// lower-case letters 'a' to 'z' for digit values >= 10. No base
// prefix (such as "0x") is added to the string.
func (x *Int) Text(base int) string {
if x == nil {
return "<nil>"
}
return string(x.abs.itoa(x.neg, base))
}
// Append appends the string representation of x, as generated by
// x.Text(base), to buf and returns the extended buffer.
func (x *Int) Append(buf []byte, base int) []byte {
if x == nil {
return append(buf, "<nil>"...)
}
return append(buf, x.abs.itoa(x.neg, base)...)
}
func (x *Int) String() string {
return x.Text(10)
}
// write count copies of text to s
func writeMultiple(s fmt.State, text string, count int) {
if len(text) > 0 {
b := []byte(text)
for ; count > 0; count-- {
s.Write(b)
}
}
}
// Format implements fmt.Formatter. It accepts the formats
// 'b' (binary), 'o' (octal), 'd' (decimal), 'x' (lowercase
// hexadecimal), and 'X' (uppercase hexadecimal).
// Also supported are the full suite of package fmt's format
// flags for integral types, including '+' and ' ' for sign
// control, '#' for leading zero in octal and for hexadecimal,
// a leading "0x" or "0X" for "%#x" and "%#X" respectively,
// specification of minimum digits precision, output field
// width, space or zero padding, and '-' for left or right
// justification.
//
func (x *Int) Format(s fmt.State, ch rune) {
// determine base
var base int
switch ch {
case 'b':
base = 2
case 'o':
base = 8
case 'd', 's', 'v':
base = 10
case 'x', 'X':
base = 16
default:
// unknown format
fmt.Fprintf(s, "%%!%c(big.Int=%s)", ch, x.String())
return
}
if x == nil {
fmt.Fprint(s, "<nil>")
return
}
// determine sign character
sign := ""
switch {
case x.neg:
sign = "-"
case s.Flag('+'): // supersedes ' ' when both specified
sign = "+"
case s.Flag(' '):
sign = " "
}
// determine prefix characters for indicating output base
prefix := ""
if s.Flag('#') {
switch ch {
case 'o': // octal
prefix = "0"
case 'x': // hexadecimal
prefix = "0x"
case 'X':
prefix = "0X"
}
}
digits := x.abs.utoa(base)
if ch == 'X' {
// faster than bytes.ToUpper
for i, d := range digits {
if 'a' <= d && d <= 'z' {
digits[i] = 'A' + (d - 'a')
}
}
}
// number of characters for the three classes of number padding
var left int // space characters to left of digits for right justification ("%8d")
var zeros int // zero characters (actually cs[0]) as left-most digits ("%.8d")
var right int // space characters to right of digits for left justification ("%-8d")
// determine number padding from precision: the least number of digits to output
precision, precisionSet := s.Precision()
if precisionSet {
switch {
case len(digits) < precision:
zeros = precision - len(digits) // count of zero padding
case len(digits) == 1 && digits[0] == '0' && precision == 0:
return // print nothing if zero value (x == 0) and zero precision ("." or ".0")
}
}
// determine field pad from width: the least number of characters to output
length := len(sign) + len(prefix) + zeros + len(digits)
if width, widthSet := s.Width(); widthSet && length < width { // pad as specified
switch d := width - length; {
case s.Flag('-'):
// pad on the right with spaces; supersedes '0' when both specified
right = d
case s.Flag('0') && !precisionSet:
// pad with zeros unless precision also specified
zeros = d
default:
// pad on the left with spaces
left = d
}
}
// print number as [left pad][sign][prefix][zero pad][digits][right pad]
writeMultiple(s, " ", left)
writeMultiple(s, sign, 1)
writeMultiple(s, prefix, 1)
writeMultiple(s, "0", zeros)
s.Write(digits)
writeMultiple(s, " ", right)
}
// scan sets z to the integer value corresponding to the longest possible prefix
// read from r representing a signed integer number in a given conversion base.
// It returns z, the actual conversion base used, and an error, if any. In the
// error case, the value of z is undefined but the returned value is nil. The
// syntax follows the syntax of integer literals in Go.
//
// The base argument must be 0 or a value from 2 through MaxBase. If the base
// is 0, the string prefix determines the actual conversion base. A prefix of
// ``0x'' or ``0X'' selects base 16; the ``0'' prefix selects base 8, and a
// ``0b'' or ``0B'' prefix selects base 2. Otherwise the selected base is 10.
//
func (z *Int) scan(r io.ByteScanner, base int) (*Int, int, error) {
// determine sign
neg, err := scanSign(r)
if err != nil {
return nil, 0, err
}
// determine mantissa
z.abs, base, _, err = z.abs.scan(r, base, false)
if err != nil {
return nil, base, err
}
z.neg = len(z.abs) > 0 && neg // 0 has no sign
return z, base, nil
}
func scanSign(r io.ByteScanner) (neg bool, err error) {
var ch byte
if ch, err = r.ReadByte(); err != nil {
return false, err
}
switch ch {
case '-':
neg = true
case '+':
// nothing to do
default:
r.UnreadByte()
}
return
}
// byteReader is a local wrapper around fmt.ScanState;
// it implements the ByteReader interface.
type byteReader struct {
fmt.ScanState
}
func (r byteReader) ReadByte() (byte, error) {
ch, size, err := r.ReadRune()
if size != 1 && err == nil {
err = fmt.Errorf("invalid rune %#U", ch)
}
return byte(ch), err
}
func (r byteReader) UnreadByte() error {
return r.UnreadRune()
}
// Scan is a support routine for fmt.Scanner; it sets z to the value of
// the scanned number. It accepts the formats 'b' (binary), 'o' (octal),
// 'd' (decimal), 'x' (lowercase hexadecimal), and 'X' (uppercase hexadecimal).
func (z *Int) Scan(s fmt.ScanState, ch rune) error {
s.SkipSpace() // skip leading space characters
base := 0
switch ch {
case 'b':
base = 2
case 'o':
base = 8
case 'd':
base = 10
case 'x', 'X':
base = 16
case 's', 'v':
// let scan determine the base
default:
return errors.New("Int.Scan: invalid verb")
}
_, _, err := z.scan(byteReader{s}, base)
return err
}

391
src/cmd/compile/internal/big/intconv_test.go
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@ -1,391 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"bytes"
"fmt"
"testing"
)
var stringTests = []struct {
in string
out string
base int
val int64
ok bool
}{
{in: ""},
{in: "a"},
{in: "z"},
{in: "+"},
{in: "-"},
{in: "0b"},
{in: "0x"},
{in: "2", base: 2},
{in: "0b2", base: 0},
{in: "08"},
{in: "8", base: 8},
{in: "0xg", base: 0},
{in: "g", base: 16},
{"0", "0", 0, 0, true},
{"0", "0", 10, 0, true},
{"0", "0", 16, 0, true},
{"+0", "0", 0, 0, true},
{"-0", "0", 0, 0, true},
{"10", "10", 0, 10, true},
{"10", "10", 10, 10, true},
{"10", "10", 16, 16, true},
{"-10", "-10", 16, -16, true},
{"+10", "10", 16, 16, true},
{"0x10", "16", 0, 16, true},
{in: "0x10", base: 16},
{"-0x10", "-16", 0, -16, true},
{"+0x10", "16", 0, 16, true},
{"00", "0", 0, 0, true},
{"0", "0", 8, 0, true},
{"07", "7", 0, 7, true},
{"7", "7", 8, 7, true},
{"023", "19", 0, 19, true},
{"23", "23", 8, 19, true},
{"cafebabe", "cafebabe", 16, 0xcafebabe, true},
{"0b0", "0", 0, 0, true},
{"-111", "-111", 2, -7, true},
{"-0b111", "-7", 0, -7, true},
{"0b1001010111", "599", 0, 0x257, true},
{"1001010111", "1001010111", 2, 0x257, true},
}
func TestIntText(t *testing.T) {
z := new(Int)
for _, test := range stringTests {
if !test.ok {
continue
}
_, ok := z.SetString(test.in, test.base)
if !ok {
t.Errorf("%v: failed to parse", test)
continue
}
base := test.base
if base == 0 {
base = 10
}
if got := z.Text(base); got != test.out {
t.Errorf("%v: got %s; want %s", test, got, test.out)
}
}
}
func TestAppendText(t *testing.T) {
z := new(Int)
var buf []byte
for _, test := range stringTests {
if !test.ok {
continue
}
_, ok := z.SetString(test.in, test.base)
if !ok {
t.Errorf("%v: failed to parse", test)
continue
}
base := test.base
if base == 0 {
base = 10
}
i := len(buf)
buf = z.Append(buf, base)
if got := string(buf[i:]); got != test.out {
t.Errorf("%v: got %s; want %s", test, got, test.out)
}
}
}
func format(base int) string {
switch base {
case 2:
return "%b"
case 8:
return "%o"
case 16:
return "%x"
}
return "%d"
}
func TestGetString(t *testing.T) {
z := new(Int)
for i, test := range stringTests {
if !test.ok {
continue
}
z.SetInt64(test.val)
if test.base == 10 {
if got := z.String(); got != test.out {
t.Errorf("#%da got %s; want %s", i, got, test.out)
}
}
if got := fmt.Sprintf(format(test.base), z); got != test.out {
t.Errorf("#%db got %s; want %s", i, got, test.out)
}
}
}
func TestSetString(t *testing.T) {
tmp := new(Int)
for i, test := range stringTests {
// initialize to a non-zero value so that issues with parsing
// 0 are detected
tmp.SetInt64(1234567890)
n1, ok1 := new(Int).SetString(test.in, test.base)
n2, ok2 := tmp.SetString(test.in, test.base)
expected := NewInt(test.val)
if ok1 != test.ok || ok2 != test.ok {
t.Errorf("#%d (input '%s') ok incorrect (should be %t)", i, test.in, test.ok)
continue
}
if !ok1 {
if n1 != nil {
t.Errorf("#%d (input '%s') n1 != nil", i, test.in)
}
continue
}
if !ok2 {
if n2 != nil {
t.Errorf("#%d (input '%s') n2 != nil", i, test.in)
}
continue
}
if ok1 && !isNormalized(n1) {
t.Errorf("#%d (input '%s'): %v is not normalized", i, test.in, *n1)
}
if ok2 && !isNormalized(n2) {
t.Errorf("#%d (input '%s'): %v is not normalized", i, test.in, *n2)
}
if n1.Cmp(expected) != 0 {
t.Errorf("#%d (input '%s') got: %s want: %d", i, test.in, n1, test.val)
}
if n2.Cmp(expected) != 0 {
t.Errorf("#%d (input '%s') got: %s want: %d", i, test.in, n2, test.val)
}
}
}
var formatTests = []struct {
input string
format string
output string
}{
{"<nil>", "%x", "<nil>"},
{"<nil>", "%#x", "<nil>"},
{"<nil>", "%#y", "%!y(big.Int=<nil>)"},
{"10", "%b", "1010"},
{"10", "%o", "12"},
{"10", "%d", "10"},
{"10", "%v", "10"},
{"10", "%x", "a"},
{"10", "%X", "A"},
{"-10", "%X", "-A"},
{"10", "%y", "%!y(big.Int=10)"},
{"-10", "%y", "%!y(big.Int=-10)"},
{"10", "%#b", "1010"},
{"10", "%#o", "012"},
{"10", "%#d", "10"},
{"10", "%#v", "10"},
{"10", "%#x", "0xa"},
{"10", "%#X", "0XA"},
{"-10", "%#X", "-0XA"},
{"10", "%#y", "%!y(big.Int=10)"},
{"-10", "%#y", "%!y(big.Int=-10)"},
{"1234", "%d", "1234"},
{"1234", "%3d", "1234"},
{"1234", "%4d", "1234"},
{"-1234", "%d", "-1234"},
{"1234", "% 5d", " 1234"},
{"1234", "%+5d", "+1234"},
{"1234", "%-5d", "1234 "},
{"1234", "%x", "4d2"},
{"1234", "%X", "4D2"},
{"-1234", "%3x", "-4d2"},
{"-1234", "%4x", "-4d2"},
{"-1234", "%5x", " -4d2"},
{"-1234", "%-5x", "-4d2 "},
{"1234", "%03d", "1234"},
{"1234", "%04d", "1234"},
{"1234", "%05d", "01234"},
{"1234", "%06d", "001234"},
{"-1234", "%06d", "-01234"},
{"1234", "%+06d", "+01234"},
{"1234", "% 06d", " 01234"},
{"1234", "%-6d", "1234 "},
{"1234", "%-06d", "1234 "},
{"-1234", "%-06d", "-1234 "},
{"1234", "%.3d", "1234"},
{"1234", "%.4d", "1234"},
{"1234", "%.5d", "01234"},
{"1234", "%.6d", "001234"},
{"-1234", "%.3d", "-1234"},
{"-1234", "%.4d", "-1234"},
{"-1234", "%.5d", "-01234"},
{"-1234", "%.6d", "-001234"},
{"1234", "%8.3d", " 1234"},
{"1234", "%8.4d", " 1234"},
{"1234", "%8.5d", " 01234"},
{"1234", "%8.6d", " 001234"},
{"-1234", "%8.3d", " -1234"},
{"-1234", "%8.4d", " -1234"},
{"-1234", "%8.5d", " -01234"},
{"-1234", "%8.6d", " -001234"},
{"1234", "%+8.3d", " +1234"},
{"1234", "%+8.4d", " +1234"},
{"1234", "%+8.5d", " +01234"},
{"1234", "%+8.6d", " +001234"},
{"-1234", "%+8.3d", " -1234"},
{"-1234", "%+8.4d", " -1234"},
{"-1234", "%+8.5d", " -01234"},
{"-1234", "%+8.6d", " -001234"},
{"1234", "% 8.3d", " 1234"},
{"1234", "% 8.4d", " 1234"},
{"1234", "% 8.5d", " 01234"},
{"1234", "% 8.6d", " 001234"},
{"-1234", "% 8.3d", " -1234"},
{"-1234", "% 8.4d", " -1234"},
{"-1234", "% 8.5d", " -01234"},
{"-1234", "% 8.6d", " -001234"},
{"1234", "%.3x", "4d2"},
{"1234", "%.4x", "04d2"},
{"1234", "%.5x", "004d2"},
{"1234", "%.6x", "0004d2"},
{"-1234", "%.3x", "-4d2"},
{"-1234", "%.4x", "-04d2"},
{"-1234", "%.5x", "-004d2"},
{"-1234", "%.6x", "-0004d2"},
{"1234", "%8.3x", " 4d2"},
{"1234", "%8.4x", " 04d2"},
{"1234", "%8.5x", " 004d2"},
{"1234", "%8.6x", " 0004d2"},
{"-1234", "%8.3x", " -4d2"},
{"-1234", "%8.4x", " -04d2"},
{"-1234", "%8.5x", " -004d2"},
{"-1234", "%8.6x", " -0004d2"},
{"1234", "%+8.3x", " +4d2"},
{"1234", "%+8.4x", " +04d2"},
{"1234", "%+8.5x", " +004d2"},
{"1234", "%+8.6x", " +0004d2"},
{"-1234", "%+8.3x", " -4d2"},
{"-1234", "%+8.4x", " -04d2"},
{"-1234", "%+8.5x", " -004d2"},
{"-1234", "%+8.6x", " -0004d2"},
{"1234", "% 8.3x", " 4d2"},
{"1234", "% 8.4x", " 04d2"},
{"1234", "% 8.5x", " 004d2"},
{"1234", "% 8.6x", " 0004d2"},
{"1234", "% 8.7x", " 00004d2"},
{"1234", "% 8.8x", " 000004d2"},
{"-1234", "% 8.3x", " -4d2"},
{"-1234", "% 8.4x", " -04d2"},
{"-1234", "% 8.5x", " -004d2"},
{"-1234", "% 8.6x", " -0004d2"},
{"-1234", "% 8.7x", "-00004d2"},
{"-1234", "% 8.8x", "-000004d2"},
{"1234", "%-8.3d", "1234 "},
{"1234", "%-8.4d", "1234 "},
{"1234", "%-8.5d", "01234 "},
{"1234", "%-8.6d", "001234 "},
{"1234", "%-8.7d", "0001234 "},
{"1234", "%-8.8d", "00001234"},
{"-1234", "%-8.3d", "-1234 "},
{"-1234", "%-8.4d", "-1234 "},
{"-1234", "%-8.5d", "-01234 "},
{"-1234", "%-8.6d", "-001234 "},
{"-1234", "%-8.7d", "-0001234"},
{"-1234", "%-8.8d", "-00001234"},
{"16777215", "%b", "111111111111111111111111"}, // 2**24 - 1
{"0", "%.d", ""},
{"0", "%.0d", ""},
{"0", "%3.d", ""},
}
func TestFormat(t *testing.T) {
for i, test := range formatTests {
var x *Int
if test.input != "<nil>" {
var ok bool
x, ok = new(Int).SetString(test.input, 0)
if !ok {
t.Errorf("#%d failed reading input %s", i, test.input)
}
}
output := fmt.Sprintf(test.format, x)
if output != test.output {
t.Errorf("#%d got %q; want %q, {%q, %q, %q}", i, output, test.output, test.input, test.format, test.output)
}
}
}
var scanTests = []struct {
input string
format string
output string
remaining int
}{
{"1010", "%b", "10", 0},
{"0b1010", "%v", "10", 0},
{"12", "%o", "10", 0},
{"012", "%v", "10", 0},
{"10", "%d", "10", 0},
{"10", "%v", "10", 0},
{"a", "%x", "10", 0},
{"0xa", "%v", "10", 0},
{"A", "%X", "10", 0},
{"-A", "%X", "-10", 0},
{"+0b1011001", "%v", "89", 0},
{"0xA", "%v", "10", 0},
{"0 ", "%v", "0", 1},
{"2+3", "%v", "2", 2},
{"0XABC 12", "%v", "2748", 3},
}
func TestScan(t *testing.T) {
var buf bytes.Buffer
for i, test := range scanTests {
x := new(Int)
buf.Reset()
buf.WriteString(test.input)
if _, err := fmt.Fscanf(&buf, test.format, x); err != nil {
t.Errorf("#%d error: %s", i, err)
}
if x.String() != test.output {
t.Errorf("#%d got %s; want %s", i, x.String(), test.output)
}
if buf.Len() != test.remaining {
t.Errorf("#%d got %d bytes remaining; want %d", i, buf.Len(), test.remaining)
}
}
}

78
src/cmd/compile/internal/big/intmarsh.go
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@ -1,78 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements encoding/decoding of Ints.
package big
import "fmt"
// Gob codec version. Permits backward-compatible changes to the encoding.
const intGobVersion byte = 1
// GobEncode implements the gob.GobEncoder interface.
func (x *Int) GobEncode() ([]byte, error) {
if x == nil {
return nil, nil
}
buf := make([]byte, 1+len(x.abs)*_S) // extra byte for version and sign bit
i := x.abs.bytes(buf) - 1 // i >= 0
b := intGobVersion << 1 // make space for sign bit
if x.neg {
b |= 1
}
buf[i] = b
return buf[i:], nil
}
// GobDecode implements the gob.GobDecoder interface.
func (z *Int) GobDecode(buf []byte) error {
if len(buf) == 0 {
// Other side sent a nil or default value.
*z = Int{}
return nil
}
b := buf[0]
if b>>1 != intGobVersion {
return fmt.Errorf("Int.GobDecode: encoding version %d not supported", b>>1)
}
z.neg = b&1 != 0
z.abs = z.abs.setBytes(buf[1:])
return nil
}
// MarshalText implements the encoding.TextMarshaler interface.
func (x *Int) MarshalText() (text []byte, err error) {
if x == nil {
return []byte("<nil>"), nil
}
return x.abs.itoa(x.neg, 10), nil
}
// UnmarshalText implements the encoding.TextUnmarshaler interface.
func (z *Int) UnmarshalText(text []byte) error {
// TODO(gri): get rid of the []byte/string conversion
if _, ok := z.SetString(string(text), 0); !ok {
return fmt.Errorf("math/big: cannot unmarshal %q into a *big.Int", text)
}
return nil
}
// The JSON marshallers are only here for API backward compatibility
// (programs that explicitly look for these two methods). JSON works
// fine with the TextMarshaler only.
// MarshalJSON implements the json.Marshaler interface.
func (x *Int) MarshalJSON() ([]byte, error) {
return x.MarshalText()
}
// UnmarshalJSON implements the json.Unmarshaler interface.
func (z *Int) UnmarshalJSON(text []byte) error {
// Ignore null, like in the main JSON package.
if string(text) == "null" {
return nil
}
return z.UnmarshalText(text)
}

121
src/cmd/compile/internal/big/intmarsh_test.go
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@ -1,121 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"bytes"
"encoding/gob"
"encoding/json"
"encoding/xml"
"testing"
)
var encodingTests = []string{
"0",
"1",
"2",
"10",
"1000",
"1234567890",
"298472983472983471903246121093472394872319615612417471234712061",
}
func TestIntGobEncoding(t *testing.T) {
var medium bytes.Buffer
enc := gob.NewEncoder(&medium)
dec := gob.NewDecoder(&medium)
for _, test := range encodingTests {
for _, sign := range []string{"", "+", "-"} {
x := sign + test
medium.Reset() // empty buffer for each test case (in case of failures)
var tx Int
tx.SetString(x, 10)
if err := enc.Encode(&tx); err != nil {
t.Errorf("encoding of %s failed: %s", &tx, err)
continue
}
var rx Int
if err := dec.Decode(&rx); err != nil {
t.Errorf("decoding of %s failed: %s", &tx, err)
continue
}
if rx.Cmp(&tx) != 0 {
t.Errorf("transmission of %s failed: got %s want %s", &tx, &rx, &tx)
}
}
}
}
// Sending a nil Int pointer (inside a slice) on a round trip through gob should yield a zero.
// TODO: top-level nils.
func TestGobEncodingNilIntInSlice(t *testing.T) {
buf := new(bytes.Buffer)
enc := gob.NewEncoder(buf)
dec := gob.NewDecoder(buf)
var in = make([]*Int, 1)
err := enc.Encode(&in)
if err != nil {
t.Errorf("gob encode failed: %q", err)
}
var out []*Int
err = dec.Decode(&out)
if err != nil {
t.Fatalf("gob decode failed: %q", err)
}
if len(out) != 1 {
t.Fatalf("wrong len; want 1 got %d", len(out))
}
var zero Int
if out[0].Cmp(&zero) != 0 {
t.Fatalf("transmission of (*Int)(nil) failed: got %s want 0", out)
}
}
func TestIntJSONEncoding(t *testing.T) {
for _, test := range encodingTests {
for _, sign := range []string{"", "+", "-"} {
x := sign + test
var tx Int
tx.SetString(x, 10)
b, err := json.Marshal(&tx)
if err != nil {
t.Errorf("marshaling of %s failed: %s", &tx, err)
continue
}
var rx Int
if err := json.Unmarshal(b, &rx); err != nil {
t.Errorf("unmarshaling of %s failed: %s", &tx, err)
continue
}
if rx.Cmp(&tx) != 0 {
t.Errorf("JSON encoding of %s failed: got %s want %s", &tx, &rx, &tx)
}
}
}
}
func TestIntXMLEncoding(t *testing.T) {
for _, test := range encodingTests {
for _, sign := range []string{"", "+", "-"} {
x := sign + test
var tx Int
tx.SetString(x, 0)
b, err := xml.Marshal(&tx)
if err != nil {
t.Errorf("marshaling of %s failed: %s", &tx, err)
continue
}
var rx Int
if err := xml.Unmarshal(b, &rx); err != nil {
t.Errorf("unmarshaling of %s failed: %s", &tx, err)
continue
}
if rx.Cmp(&tx) != 0 {
t.Errorf("XML encoding of %s failed: got %s want %s", &tx, &rx, &tx)
}
}
}
}

1305
src/cmd/compile/internal/big/nat.go
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651
src/cmd/compile/internal/big/nat_test.go
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@ -1,651 +0,0 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"fmt"
"runtime"
"strings"
"testing"
)
var cmpTests = []struct {
x, y nat
r int
}{
{nil, nil, 0},
{nil, nat(nil), 0},
{nat(nil), nil, 0},
{nat(nil), nat(nil), 0},
{nat{0}, nat{0}, 0},
{nat{0}, nat{1}, -1},
{nat{1}, nat{0}, 1},
{nat{1}, nat{1}, 0},
{nat{0, _M}, nat{1}, 1},
{nat{1}, nat{0, _M}, -1},
{nat{1, _M}, nat{0, _M}, 1},
{nat{0, _M}, nat{1, _M}, -1},
{nat{16, 571956, 8794, 68}, nat{837, 9146, 1, 754489}, -1},
{nat{34986, 41, 105, 1957}, nat{56, 7458, 104, 1957}, 1},
}
func TestCmp(t *testing.T) {
for i, a := range cmpTests {
r := a.x.cmp(a.y)
if r != a.r {
t.Errorf("#%d got r = %v; want %v", i, r, a.r)
}
}
}
type funNN func(z, x, y nat) nat
type argNN struct {
z, x, y nat
}
var sumNN = []argNN{
{},
{nat{1}, nil, nat{1}},
{nat{1111111110}, nat{123456789}, nat{987654321}},
{nat{0, 0, 0, 1}, nil, nat{0, 0, 0, 1}},
{nat{0, 0, 0, 1111111110}, nat{0, 0, 0, 123456789}, nat{0, 0, 0, 987654321}},
{nat{0, 0, 0, 1}, nat{0, 0, _M}, nat{0, 0, 1}},
}
var prodNN = []argNN{
{},
{nil, nil, nil},
{nil, nat{991}, nil},
{nat{991}, nat{991}, nat{1}},
{nat{991 * 991}, nat{991}, nat{991}},
{nat{0, 0, 991 * 991}, nat{0, 991}, nat{0, 991}},
{nat{1 * 991, 2 * 991, 3 * 991, 4 * 991}, nat{1, 2, 3, 4}, nat{991}},
{nat{4, 11, 20, 30, 20, 11, 4}, nat{1, 2, 3, 4}, nat{4, 3, 2, 1}},
// 3^100 * 3^28 = 3^128
{
natFromString("11790184577738583171520872861412518665678211592275841109096961"),
natFromString("515377520732011331036461129765621272702107522001"),
natFromString("22876792454961"),
},
// z = 111....1 (70000 digits)
// x = 10^(99*700) + ... + 10^1400 + 10^700 + 1
// y = 111....1 (700 digits, larger than Karatsuba threshold on 32-bit and 64-bit)
{
natFromString(strings.Repeat("1", 70000)),
natFromString("1" + strings.Repeat(strings.Repeat("0", 699)+"1", 99)),
natFromString(strings.Repeat("1", 700)),
},
// z = 111....1 (20000 digits)
// x = 10^10000 + 1
// y = 111....1 (10000 digits)
{
natFromString(strings.Repeat("1", 20000)),
natFromString("1" + strings.Repeat("0", 9999) + "1"),
natFromString(strings.Repeat("1", 10000)),
},
}
func natFromString(s string) nat {
x, _, _, err := nat(nil).scan(strings.NewReader(s), 0, false)
if err != nil {
panic(err)
}
return x
}
func TestSet(t *testing.T) {
for _, a := range sumNN {
z := nat(nil).set(a.z)
if z.cmp(a.z) != 0 {
t.Errorf("got z = %v; want %v", z, a.z)
}
}
}
func testFunNN(t *testing.T, msg string, f funNN, a argNN) {
z := f(nil, a.x, a.y)
if z.cmp(a.z) != 0 {
t.Errorf("%s%+v\n\tgot z = %v; want %v", msg, a, z, a.z)
}
}
func TestFunNN(t *testing.T) {
for _, a := range sumNN {
arg := a
testFunNN(t, "add", nat.add, arg)
arg = argNN{a.z, a.y, a.x}
testFunNN(t, "add symmetric", nat.add, arg)
arg = argNN{a.x, a.z, a.y}
testFunNN(t, "sub", nat.sub, arg)
arg = argNN{a.y, a.z, a.x}
testFunNN(t, "sub symmetric", nat.sub, arg)
}
for _, a := range prodNN {
arg := a
testFunNN(t, "mul", nat.mul, arg)
arg = argNN{a.z, a.y, a.x}
testFunNN(t, "mul symmetric", nat.mul, arg)
}
}
var mulRangesN = []struct {
a, b uint64
prod string
}{
{0, 0, "0"},
{1, 1, "1"},
{1, 2, "2"},
{1, 3, "6"},
{10, 10, "10"},
{0, 100, "0"},
{0, 1e9, "0"},
{1, 0, "1"}, // empty range
{100, 1, "1"}, // empty range
{1, 10, "3628800"}, // 10!
{1, 20, "2432902008176640000"}, // 20!
{1, 100,
"933262154439441526816992388562667004907159682643816214685929" +
"638952175999932299156089414639761565182862536979208272237582" +
"51185210916864000000000000000000000000", // 100!
},
}
func TestMulRangeN(t *testing.T) {
for i, r := range mulRangesN {
prod := string(nat(nil).mulRange(r.a, r.b).utoa(10))
if prod != r.prod {
t.Errorf("#%d: got %s; want %s", i, prod, r.prod)
}
}
}
// allocBytes returns the number of bytes allocated by invoking f.
func allocBytes(f func()) uint64 {
var stats runtime.MemStats
runtime.ReadMemStats(&stats)
t := stats.TotalAlloc
f()
runtime.ReadMemStats(&stats)
return stats.TotalAlloc - t
}
// TestMulUnbalanced tests that multiplying numbers of different lengths
// does not cause deep recursion and in turn allocate too much memory.
// Test case for issue 3807.
func TestMulUnbalanced(t *testing.T) {
defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
x := rndNat(50000)
y := rndNat(40)
allocSize := allocBytes(func() {
nat(nil).mul(x, y)
})
inputSize := uint64(len(x)+len(y)) * _S
if ratio := allocSize / uint64(inputSize); ratio > 10 {
t.Errorf("multiplication uses too much memory (%d > %d times the size of inputs)", allocSize, ratio)
}
}
func rndNat(n int) nat {
return nat(rndV(n)).norm()
}
func BenchmarkMul(b *testing.B) {
mulx := rndNat(1e4)
muly := rndNat(1e4)
b.ResetTimer()
for i := 0; i < b.N; i++ {
var z nat
z.mul(mulx, muly)
}
}
func TestNLZ(t *testing.T) {
var x Word = _B >> 1
for i := 0; i <= _W; i++ {
if int(nlz(x)) != i {
t.Errorf("failed at %x: got %d want %d", x, nlz(x), i)
}
x >>= 1
}
}
type shiftTest struct {
in nat
shift uint
out nat
}
var leftShiftTests = []shiftTest{
{nil, 0, nil},
{nil, 1, nil},
{natOne, 0, natOne},
{natOne, 1, natTwo},
{nat{1 << (_W - 1)}, 1, nat{0}},
{nat{1 << (_W - 1), 0}, 1, nat{0, 1}},
}
func TestShiftLeft(t *testing.T) {
for i, test := range leftShiftTests {
var z nat
z = z.shl(test.in, test.shift)
for j, d := range test.out {
if j >= len(z) || z[j] != d {
t.Errorf("#%d: got: %v want: %v", i, z, test.out)
break
}
}
}
}
var rightShiftTests = []shiftTest{
{nil, 0, nil},
{nil, 1, nil},
{natOne, 0, natOne},
{natOne, 1, nil},
{natTwo, 1, natOne},
{nat{0, 1}, 1, nat{1 << (_W - 1)}},
{nat{2, 1, 1}, 1, nat{1<<(_W-1) + 1, 1 << (_W - 1)}},
}
func TestShiftRight(t *testing.T) {
for i, test := range rightShiftTests {
var z nat
z = z.shr(test.in, test.shift)
for j, d := range test.out {
if j >= len(z) || z[j] != d {
t.Errorf("#%d: got: %v want: %v", i, z, test.out)
break
}
}
}
}
type modWTest struct {
in string
dividend string
out string
}
var modWTests32 = []modWTest{
{"23492635982634928349238759823742", "252341", "220170"},
}
var modWTests64 = []modWTest{
{"6527895462947293856291561095690465243862946", "524326975699234", "375066989628668"},
}
func runModWTests(t *testing.T, tests []modWTest) {
for i, test := range tests {
in, _ := new(Int).SetString(test.in, 10)
d, _ := new(Int).SetString(test.dividend, 10)
out, _ := new(Int).SetString(test.out, 10)
r := in.abs.modW(d.abs[0])
if r != out.abs[0] {
t.Errorf("#%d failed: got %d want %s", i, r, out)
}
}
}
func TestModW(t *testing.T) {
if _W >= 32 {
runModWTests(t, modWTests32)
}
if _W >= 64 {
runModWTests(t, modWTests64)
}
}
func TestTrailingZeroBits(t *testing.T) {
// test 0 case explicitly
if n := trailingZeroBits(0); n != 0 {
t.Errorf("got trailingZeroBits(0) = %d; want 0", n)
}
x := Word(1)
for i := uint(0); i < _W; i++ {
n := trailingZeroBits(x)
if n != i {
t.Errorf("got trailingZeroBits(%#x) = %d; want %d", x, n, i%_W)
}
x <<= 1
}
// test 0 case explicitly
if n := nat(nil).trailingZeroBits(); n != 0 {
t.Errorf("got nat(nil).trailingZeroBits() = %d; want 0", n)
}
y := nat(nil).set(natOne)
for i := uint(0); i <= 3*_W; i++ {
n := y.trailingZeroBits()
if n != i {
t.Errorf("got 0x%s.trailingZeroBits() = %d; want %d", y.utoa(16), n, i)
}
y = y.shl(y, 1)
}
}
var montgomeryTests = []struct {
x, y, m string
k0 uint64
out32, out64 string
}{
{
"0xffffffffffffffffffffffffffffffffffffffffffffffffe",
"0xffffffffffffffffffffffffffffffffffffffffffffffffe",
"0xfffffffffffffffffffffffffffffffffffffffffffffffff",
1,
"0x1000000000000000000000000000000000000000000",
"0x10000000000000000000000000000000000",
},
{
"0x000000000ffffff5",
"0x000000000ffffff0",
"0x0000000010000001",
0xff0000000fffffff,
"0x000000000bfffff4",
"0x0000000003400001",
},
{
"0x0000000080000000",
"0x00000000ffffffff",
"0x1000000000000001",
0xfffffffffffffff,
"0x0800000008000001",
"0x0800000008000001",
},
{
"0x0000000080000000",
"0x0000000080000000",
"0xffffffff00000001",
0xfffffffeffffffff,
"0xbfffffff40000001",
"0xbfffffff40000001",
},
{
"0x0000000080000000",
"0x0000000080000000",
"0x00ffffff00000001",
0xfffffeffffffff,
"0xbfffff40000001",
"0xbfffff40000001",
},
{
"0x0000000080000000",
"0x0000000080000000",
"0x0000ffff00000001",
0xfffeffffffff,
"0xbfff40000001",
"0xbfff40000001",
},
{
"0x3321ffffffffffffffffffffffffffff00000000000022222623333333332bbbb888c0",
"0x3321ffffffffffffffffffffffffffff00000000000022222623333333332bbbb888c0",
"0x33377fffffffffffffffffffffffffffffffffffffffffffff0000000000022222eee1",
0xdecc8f1249812adf,
"0x04eb0e11d72329dc0915f86784820fc403275bf2f6620a20e0dd344c5cd0875e50deb5",
"0x0d7144739a7d8e11d72329dc0915f86784820fc403275bf2f61ed96f35dd34dbb3d6a0",
},
{
"0x10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000ffffffffffffffffffffffffffffffff00000000000022222223333333333444444444",
"0x10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000ffffffffffffffffffffffffffffffff999999999999999aaabbbbbbbbcccccccccccc",
"0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff33377fffffffffffffffffffffffffffffffffffffffffffff0000000000022222eee1",
0xdecc8f1249812adf,
"0x5c0d52f451aec609b15da8e5e5626c4eaa88723bdeac9d25ca9b961269400410ca208a16af9c2fb07d7a11c7772cba02c22f9711078d51a3797eb18e691295293284d988e349fa6deba46b25a4ecd9f715",
"0x92fcad4b5c0d52f451aec609b15da8e5e5626c4eaa88723bdeac9d25ca9b961269400410ca208a16af9c2fb07d799c32fe2f3cc5422f9711078d51a3797eb18e691295293284d8f5e69caf6decddfe1df6",
},
}
func TestMontgomery(t *testing.T) {
one := NewInt(1)
_B := new(Int).Lsh(one, _W)
for i, test := range montgomeryTests {
x := natFromString(test.x)
y := natFromString(test.y)
m := natFromString(test.m)
for len(x) < len(m) {
x = append(x, 0)
}
for len(y) < len(m) {
y = append(y, 0)
}
if x.cmp(m) > 0 {
_, r := nat(nil).div(nil, x, m)
t.Errorf("#%d: x > m (0x%s > 0x%s; use 0x%s)", i, x.utoa(16), m.utoa(16), r.utoa(16))
}
if y.cmp(m) > 0 {
_, r := nat(nil).div(nil, x, m)
t.Errorf("#%d: y > m (0x%s > 0x%s; use 0x%s)", i, y.utoa(16), m.utoa(16), r.utoa(16))
}
var out nat
if _W == 32 {
out = natFromString(test.out32)
} else {
out = natFromString(test.out64)
}
// t.Logf("#%d: len=%d\n", i, len(m))
// check output in table
xi := &Int{abs: x}
yi := &Int{abs: y}
mi := &Int{abs: m}
p := new(Int).Mod(new(Int).Mul(xi, new(Int).Mul(yi, new(Int).ModInverse(new(Int).Lsh(one, uint(len(m))*_W), mi))), mi)
if out.cmp(p.abs.norm()) != 0 {
t.Errorf("#%d: out in table=0x%s, computed=0x%s", i, out.utoa(16), p.abs.norm().utoa(16))
}
// check k0 in table
k := new(Int).Mod(&Int{abs: m}, _B)
k = new(Int).Sub(_B, k)
k = new(Int).Mod(k, _B)
k0 := Word(new(Int).ModInverse(k, _B).Uint64())
if k0 != Word(test.k0) {
t.Errorf("#%d: k0 in table=%#x, computed=%#x\n", i, test.k0, k0)
}
// check montgomery with correct k0 produces correct output
z := nat(nil).montgomery(x, y, m, k0, len(m))
z = z.norm()
if z.cmp(out) != 0 {
t.Errorf("#%d: got 0x%s want 0x%s", i, z.utoa(16), out.utoa(16))
}
}
}
var expNNTests = []struct {
x, y, m string
out string
}{
{"0", "0", "0", "1"},
{"0", "0", "1", "0"},
{"1", "1", "1", "0"},
{"2", "1", "1", "0"},
{"2", "2", "1", "0"},
{"10", "100000000000", "1", "0"},
{"0x8000000000000000", "2", "", "0x40000000000000000000000000000000"},
{"0x8000000000000000", "2", "6719", "4944"},
{"0x8000000000000000", "3", "6719", "5447"},
{"0x8000000000000000", "1000", "6719", "1603"},
{"0x8000000000000000", "1000000", "6719", "3199"},
{
"2938462938472983472983659726349017249287491026512746239764525612965293865296239471239874193284792387498274256129746192347",
"298472983472983471903246121093472394872319615612417471234712061",
"29834729834729834729347290846729561262544958723956495615629569234729836259263598127342374289365912465901365498236492183464",
"23537740700184054162508175125554701713153216681790245129157191391322321508055833908509185839069455749219131480588829346291",
},
{
"11521922904531591643048817447554701904414021819823889996244743037378330903763518501116638828335352811871131385129455853417360623007349090150042001944696604737499160174391019030572483602867266711107136838523916077674888297896995042968746762200926853379",
"426343618817810911523",
"444747819283133684179",
"42",
},
}
func TestExpNN(t *testing.T) {
for i, test := range expNNTests {
x := natFromString(test.x)
y := natFromString(test.y)
out := natFromString(test.out)
var m nat
if len(test.m) > 0 {
m = natFromString(test.m)
}
z := nat(nil).expNN(x, y, m)
if z.cmp(out) != 0 {
t.Errorf("#%d got %s want %s", i, z.utoa(10), out.utoa(10))
}
}
}
func BenchmarkExp3Power(b *testing.B) {
const x = 3
for _, y := range []Word{
0x10, 0x40, 0x100, 0x400, 0x1000, 0x4000, 0x10000, 0x40000, 0x100000, 0x400000,
} {
b.Run(fmt.Sprintf("%#x", y), func(b *testing.B) {
var z nat
for i := 0; i < b.N; i++ {
z.expWW(x, y)
}
})
}
}
func fibo(n int) nat {
switch n {
case 0:
return nil
case 1:
return nat{1}
}
f0 := fibo(0)
f1 := fibo(1)
var f2 nat
for i := 1; i < n; i++ {
f2 = f2.add(f0, f1)
f0, f1, f2 = f1, f2, f0
}
return f1
}
var fiboNums = []string{
"0",
"55",
"6765",
"832040",
"102334155",
"12586269025",
"1548008755920",
"190392490709135",
"23416728348467685",
"2880067194370816120",
"354224848179261915075",
}
func TestFibo(t *testing.T) {
for i, want := range fiboNums {
n := i * 10
got := string(fibo(n).utoa(10))
if got != want {
t.Errorf("fibo(%d) failed: got %s want %s", n, got, want)
}
}
}
func BenchmarkFibo(b *testing.B) {
for i := 0; i < b.N; i++ {
fibo(1e0)
fibo(1e1)
fibo(1e2)
fibo(1e3)
fibo(1e4)
fibo(1e5)
}
}
var bitTests = []struct {
x string
i uint
want uint
}{
{"0", 0, 0},
{"0", 1, 0},
{"0", 1000, 0},
{"0x1", 0, 1},
{"0x10", 0, 0},
{"0x10", 3, 0},
{"0x10", 4, 1},
{"0x10", 5, 0},
{"0x8000000000000000", 62, 0},
{"0x8000000000000000", 63, 1},
{"0x8000000000000000", 64, 0},
{"0x3" + strings.Repeat("0", 32), 127, 0},
{"0x3" + strings.Repeat("0", 32), 128, 1},
{"0x3" + strings.Repeat("0", 32), 129, 1},
{"0x3" + strings.Repeat("0", 32), 130, 0},
}
func TestBit(t *testing.T) {
for i, test := range bitTests {
x := natFromString(test.x)
if got := x.bit(test.i); got != test.want {
t.Errorf("#%d: %s.bit(%d) = %v; want %v", i, test.x, test.i, got, test.want)
}
}
}
var stickyTests = []struct {
x string
i uint
want uint
}{
{"0", 0, 0},
{"0", 1, 0},
{"0", 1000, 0},
{"0x1", 0, 0},
{"0x1", 1, 1},
{"0x1350", 0, 0},
{"0x1350", 4, 0},
{"0x1350", 5, 1},
{"0x8000000000000000", 63, 0},
{"0x8000000000000000", 64, 1},
{"0x1" + strings.Repeat("0", 100), 400, 0},
{"0x1" + strings.Repeat("0", 100), 401, 1},
}
func TestSticky(t *testing.T) {
for i, test := range stickyTests {
x := natFromString(test.x)
if got := x.sticky(test.i); got != test.want {
t.Errorf("#%d: %s.sticky(%d) = %v; want %v", i, test.x, test.i, got, test.want)
}
if test.want == 1 {
// all subsequent i's should also return 1
for d := uint(1); d <= 3; d++ {
if got := x.sticky(test.i + d); got != 1 {
t.Errorf("#%d: %s.sticky(%d) = %v; want %v", i, test.x, test.i+d, got, 1)
}
}
}
}
}

492
src/cmd/compile/internal/big/natconv.go
View file

@ -1,492 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements nat-to-string conversion functions.
package big
import (
"errors"
"fmt"
"io"
"math"
"sync"
)
const digits = "0123456789abcdefghijklmnopqrstuvwxyz"
// Note: MaxBase = len(digits), but it must remain a rune constant
// for API compatibility.
// MaxBase is the largest number base accepted for string conversions.
const MaxBase = 'z' - 'a' + 10 + 1
// maxPow returns (b**n, n) such that b**n is the largest power b**n <= _M.
// For instance maxPow(10) == (1e19, 19) for 19 decimal digits in a 64bit Word.
// In other words, at most n digits in base b fit into a Word.
// TODO(gri) replace this with a table, generated at build time.
func maxPow(b Word) (p Word, n int) {
p, n = b, 1 // assuming b <= _M
for max := _M / b; p <= max; {
// p == b**n && p <= max
p *= b
n++
}
// p == b**n && p <= _M
return
}
// pow returns x**n for n > 0, and 1 otherwise.
func pow(x Word, n int) (p Word) {
// n == sum of bi * 2**i, for 0 <= i < imax, and bi is 0 or 1
// thus x**n == product of x**(2**i) for all i where bi == 1
// (Russian Peasant Method for exponentiation)
p = 1
for n > 0 {
if n&1 != 0 {
p *= x
}
x *= x
n >>= 1
}
return
}
// scan scans the number corresponding to the longest possible prefix
// from r representing an unsigned number in a given conversion base.
// It returns the corresponding natural number res, the actual base b,
// a digit count, and a read or syntax error err, if any.
//
// number = [ prefix ] mantissa .
// prefix = "0" [ "x" | "X" | "b" | "B" ] .
// mantissa = digits | digits "." [ digits ] | "." digits .
// digits = digit { digit } .
// digit = "0" ... "9" | "a" ... "z" | "A" ... "Z" .
//
// Unless fracOk is set, the base argument must be 0 or a value between
// 2 and MaxBase. If fracOk is set, the base argument must be one of
// 0, 2, 10, or 16. Providing an invalid base argument leads to a run-
// time panic.
//
// For base 0, the number prefix determines the actual base: A prefix of
// ``0x'' or ``0X'' selects base 16; if fracOk is not set, the ``0'' prefix
// selects base 8, and a ``0b'' or ``0B'' prefix selects base 2. Otherwise
// the selected base is 10 and no prefix is accepted.
//
// If fracOk is set, an octal prefix is ignored (a leading ``0'' simply
// stands for a zero digit), and a period followed by a fractional part
// is permitted. The result value is computed as if there were no period
// present; and the count value is used to determine the fractional part.
//
// A result digit count > 0 corresponds to the number of (non-prefix) digits
// parsed. A digit count <= 0 indicates the presence of a period (if fracOk
// is set, only), and -count is the number of fractional digits found.
// In this case, the actual value of the scanned number is res * b**count.
//
func (z nat) scan(r io.ByteScanner, base int, fracOk bool) (res nat, b, count int, err error) {
// reject illegal bases
baseOk := base == 0 ||
!fracOk && 2 <= base && base <= MaxBase ||
fracOk && (base == 2 || base == 10 || base == 16)
if !baseOk {
panic(fmt.Sprintf("illegal number base %d", base))
}
// one char look-ahead
ch, err := r.ReadByte()
if err != nil {
return
}
// determine actual base
b = base
if base == 0 {
// actual base is 10 unless there's a base prefix
b = 10
if ch == '0' {
count = 1
switch ch, err = r.ReadByte(); err {
case nil:
// possibly one of 0x, 0X, 0b, 0B
if !fracOk {
b = 8
}
switch ch {
case 'x', 'X':
b = 16
case 'b', 'B':
b = 2
}
switch b {
case 16, 2:
count = 0 // prefix is not counted
if ch, err = r.ReadByte(); err != nil {
// io.EOF is also an error in this case
return
}
case 8:
count = 0 // prefix is not counted
}
case io.EOF:
// input is "0"
res = z[:0]
err = nil
return
default:
// read error
return
}
}
}
// convert string
// Algorithm: Collect digits in groups of at most n digits in di
// and then use mulAddWW for every such group to add them to the
// result.
z = z[:0]
b1 := Word(b)
bn, n := maxPow(b1) // at most n digits in base b1 fit into Word
di := Word(0) // 0 <= di < b1**i < bn
i := 0 // 0 <= i < n
dp := -1 // position of decimal point
for {
if fracOk && ch == '.' {
fracOk = false
dp = count
// advance
if ch, err = r.ReadByte(); err != nil {
if err == io.EOF {
err = nil
break
}
return
}
}
// convert rune into digit value d1
var d1 Word
switch {
case '0' <= ch && ch <= '9':
d1 = Word(ch - '0')
case 'a' <= ch && ch <= 'z':
d1 = Word(ch - 'a' + 10)
case 'A' <= ch && ch <= 'Z':
d1 = Word(ch - 'A' + 10)
default:
d1 = MaxBase + 1
}
if d1 >= b1 {
r.UnreadByte() // ch does not belong to number anymore
break
}
count++
// collect d1 in di
di = di*b1 + d1
i++
// if di is "full", add it to the result
if i == n {
z = z.mulAddWW(z, bn, di)
di = 0
i = 0
}
// advance
if ch, err = r.ReadByte(); err != nil {
if err == io.EOF {
err = nil
break
}
return
}
}
if count == 0 {
// no digits found
switch {
case base == 0 && b == 8:
// there was only the octal prefix 0 (possibly followed by digits > 7);
// count as one digit and return base 10, not 8
count = 1
b = 10
case base != 0 || b != 8:
// there was neither a mantissa digit nor the octal prefix 0
err = errors.New("syntax error scanning number")
}
return
}
// count > 0
// add remaining digits to result
if i > 0 {
z = z.mulAddWW(z, pow(b1, i), di)
}
res = z.norm()
// adjust for fraction, if any
if dp >= 0 {
// 0 <= dp <= count > 0
count = dp - count
}
return
}
// utoa converts x to an ASCII representation in the given base;
// base must be between 2 and MaxBase, inclusive.
func (x nat) utoa(base int) []byte {
return x.itoa(false, base)
}
// itoa is like utoa but it prepends a '-' if neg && x != 0.
func (x nat) itoa(neg bool, base int) []byte {
if base < 2 || base > MaxBase {
panic("invalid base")
}
// x == 0
if len(x) == 0 {
return []byte("0")
}
// len(x) > 0
// allocate buffer for conversion
i := int(float64(x.bitLen())/math.Log2(float64(base))) + 1 // off by 1 at most
if neg {
i++
}
s := make([]byte, i)
// convert power of two and non power of two bases separately
if b := Word(base); b == b&-b {
// shift is base b digit size in bits
shift := trailingZeroBits(b) // shift > 0 because b >= 2
mask := Word(1<<shift - 1)
w := x[0] // current word
nbits := uint(_W) // number of unprocessed bits in w
// convert less-significant words (include leading zeros)
for k := 1; k < len(x); k++ {
// convert full digits
for nbits >= shift {
i--
s[i] = digits[w&mask]
w >>= shift
nbits -= shift
}
// convert any partial leading digit and advance to next word
if nbits == 0 {
// no partial digit remaining, just advance
w = x[k]
nbits = _W
} else {
// partial digit in current word w (== x[k-1]) and next word x[k]
w |= x[k] << nbits
i--
s[i] = digits[w&mask]
// advance
w = x[k] >> (shift - nbits)
nbits = _W - (shift - nbits)
}
}
// convert digits of most-significant word w (omit leading zeros)
for w != 0 {
i--
s[i] = digits[w&mask]
w >>= shift
}
} else {
bb, ndigits := maxPow(b)
// construct table of successive squares of bb*leafSize to use in subdivisions
// result (table != nil) <=> (len(x) > leafSize > 0)
table := divisors(len(x), b, ndigits, bb)
// preserve x, create local copy for use by convertWords
q := nat(nil).set(x)
// convert q to string s in base b
q.convertWords(s, b, ndigits, bb, table)
// strip leading zeros
// (x != 0; thus s must contain at least one non-zero digit
// and the loop will terminate)
i = 0
for s[i] == '0' {
i++
}
}
if neg {
i--
s[i] = '-'
}
return s[i:]
}
// Convert words of q to base b digits in s. If q is large, it is recursively "split in half"
// by nat/nat division using tabulated divisors. Otherwise, it is converted iteratively using
// repeated nat/Word division.
//
// The iterative method processes n Words by n divW() calls, each of which visits every Word in the
// incrementally shortened q for a total of n + (n-1) + (n-2) ... + 2 + 1, or n(n+1)/2 divW()'s.
// Recursive conversion divides q by its approximate square root, yielding two parts, each half
// the size of q. Using the iterative method on both halves means 2 * (n/2)(n/2 + 1)/2 divW()'s
// plus the expensive long div(). Asymptotically, the ratio is favorable at 1/2 the divW()'s, and
// is made better by splitting the subblocks recursively. Best is to split blocks until one more
// split would take longer (because of the nat/nat div()) than the twice as many divW()'s of the
// iterative approach. This threshold is represented by leafSize. Benchmarking of leafSize in the
// range 2..64 shows that values of 8 and 16 work well, with a 4x speedup at medium lengths and
// ~30x for 20000 digits. Use nat_test.go's BenchmarkLeafSize tests to optimize leafSize for
// specific hardware.
//
func (q nat) convertWords(s []byte, b Word, ndigits int, bb Word, table []divisor) {
// split larger blocks recursively
if table != nil {
// len(q) > leafSize > 0
var r nat
index := len(table) - 1
for len(q) > leafSize {
// find divisor close to sqrt(q) if possible, but in any case < q
maxLength := q.bitLen() // ~= log2 q, or at of least largest possible q of this bit length
minLength := maxLength >> 1 // ~= log2 sqrt(q)
for index > 0 && table[index-1].nbits > minLength {
index-- // desired
}
if table[index].nbits >= maxLength && table[index].bbb.cmp(q) >= 0 {
index--
if index < 0 {
panic("internal inconsistency")
}
}
// split q into the two digit number (q'*bbb + r) to form independent subblocks
q, r = q.div(r, q, table[index].bbb)
// convert subblocks and collect results in s[:h] and s[h:]
h := len(s) - table[index].ndigits
r.convertWords(s[h:], b, ndigits, bb, table[0:index])
s = s[:h] // == q.convertWords(s, b, ndigits, bb, table[0:index+1])
}
}
// having split any large blocks now process the remaining (small) block iteratively
i := len(s)
var r Word
if b == 10 {
// hard-coding for 10 here speeds this up by 1.25x (allows for / and % by constants)
for len(q) > 0 {
// extract least significant, base bb "digit"
q, r = q.divW(q, bb)
for j := 0; j < ndigits && i > 0; j++ {
i--
// avoid % computation since r%10 == r - int(r/10)*10;
// this appears to be faster for BenchmarkString10000Base10
// and smaller strings (but a bit slower for larger ones)
t := r / 10
s[i] = '0' + byte(r-t*10)
r = t
}
}
} else {
for len(q) > 0 {
// extract least significant, base bb "digit"
q, r = q.divW(q, bb)
for j := 0; j < ndigits && i > 0; j++ {
i--
s[i] = digits[r%b]
r /= b
}
}
}
// prepend high-order zeros
for i > 0 { // while need more leading zeros
i--
s[i] = '0'
}
}
// Split blocks greater than leafSize Words (or set to 0 to disable recursive conversion)
// Benchmark and configure leafSize using: go test -bench="Leaf"
// 8 and 16 effective on 3.0 GHz Xeon "Clovertown" CPU (128 byte cache lines)
// 8 and 16 effective on 2.66 GHz Core 2 Duo "Penryn" CPU
var leafSize int = 8 // number of Word-size binary values treat as a monolithic block
type divisor struct {
bbb nat // divisor
nbits int // bit length of divisor (discounting leading zeros) ~= log2(bbb)
ndigits int // digit length of divisor in terms of output base digits
}
var cacheBase10 struct {
sync.Mutex
table [64]divisor // cached divisors for base 10
}
// expWW computes x**y
func (z nat) expWW(x, y Word) nat {
return z.expNN(nat(nil).setWord(x), nat(nil).setWord(y), nil)
}
// construct table of powers of bb*leafSize to use in subdivisions
func divisors(m int, b Word, ndigits int, bb Word) []divisor {
// only compute table when recursive conversion is enabled and x is large
if leafSize == 0 || m <= leafSize {
return nil
}
// determine k where (bb**leafSize)**(2**k) >= sqrt(x)
k := 1
for words := leafSize; words < m>>1 && k < len(cacheBase10.table); words <<= 1 {
k++
}
// reuse and extend existing table of divisors or create new table as appropriate
var table []divisor // for b == 10, table overlaps with cacheBase10.table
if b == 10 {
cacheBase10.Lock()
table = cacheBase10.table[0:k] // reuse old table for this conversion
} else {
table = make([]divisor, k) // create new table for this conversion
}
// extend table
if table[k-1].ndigits == 0 {
// add new entries as needed
var larger nat
for i := 0; i < k; i++ {
if table[i].ndigits == 0 {
if i == 0 {
table[0].bbb = nat(nil).expWW(bb, Word(leafSize))
table[0].ndigits = ndigits * leafSize
} else {
table[i].bbb = nat(nil).mul(table[i-1].bbb, table[i-1].bbb)
table[i].ndigits = 2 * table[i-1].ndigits
}
// optimization: exploit aggregated extra bits in macro blocks
larger = nat(nil).set(table[i].bbb)
for mulAddVWW(larger, larger, b, 0) == 0 {
table[i].bbb = table[i].bbb.set(larger)
table[i].ndigits++
}
table[i].nbits = table[i].bbb.bitLen()
}
}
}
if b == 10 {
cacheBase10.Unlock()
}
return table
}

379
src/cmd/compile/internal/big/natconv_test.go
View file

@ -1,379 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"bytes"
"fmt"
"io"
"strings"
"testing"
)
func itoa(x nat, base int) []byte {
// special cases
switch {
case base < 2:
panic("illegal base")
case len(x) == 0:
return []byte("0")
}
// allocate buffer for conversion
i := x.bitLen()/log2(Word(base)) + 1 // +1: round up
s := make([]byte, i)
// don't destroy x
q := nat(nil).set(x)
// convert
for len(q) > 0 {
i--
var r Word
q, r = q.divW(q, Word(base))
s[i] = digits[r]
}
return s[i:]
}
var strTests = []struct {
x nat // nat value to be converted
b int // conversion base
s string // expected result
}{
{nil, 2, "0"},
{nat{1}, 2, "1"},
{nat{0xc5}, 2, "11000101"},
{nat{03271}, 8, "3271"},
{nat{10}, 10, "10"},
{nat{1234567890}, 10, "1234567890"},
{nat{0xdeadbeef}, 16, "deadbeef"},
{nat{0x229be7}, 17, "1a2b3c"},
{nat{0x309663e6}, 32, "o9cov6"},
}
func TestString(t *testing.T) {
// test invalid base explicitly
var panicStr string
func() {
defer func() {
panicStr = recover().(string)
}()
natOne.utoa(1)
}()
if panicStr != "invalid base" {
t.Errorf("expected panic for invalid base")
}
for _, a := range strTests {
s := string(a.x.utoa(a.b))
if s != a.s {
t.Errorf("string%+v\n\tgot s = %s; want %s", a, s, a.s)
}
x, b, _, err := nat(nil).scan(strings.NewReader(a.s), a.b, false)
if x.cmp(a.x) != 0 {
t.Errorf("scan%+v\n\tgot z = %v; want %v", a, x, a.x)
}
if b != a.b {
t.Errorf("scan%+v\n\tgot b = %d; want %d", a, b, a.b)
}
if err != nil {
t.Errorf("scan%+v\n\tgot error = %s", a, err)
}
}
}
var natScanTests = []struct {
s string // string to be scanned
base int // input base
frac bool // fraction ok
x nat // expected nat
b int // expected base
count int // expected digit count
ok bool // expected success
next rune // next character (or 0, if at EOF)
}{
// error: no mantissa
{},
{s: "?"},
{base: 10},
{base: 36},
{s: "?", base: 10},
{s: "0x"},
{s: "345", base: 2},
// error: incorrect use of decimal point
{s: ".0"},
{s: ".0", base: 10},
{s: ".", base: 0},
{s: "0x.0"},
// no errors
{"0", 0, false, nil, 10, 1, true, 0},
{"0", 10, false, nil, 10, 1, true, 0},
{"0", 36, false, nil, 36, 1, true, 0},
{"1", 0, false, nat{1}, 10, 1, true, 0},
{"1", 10, false, nat{1}, 10, 1, true, 0},
{"0 ", 0, false, nil, 10, 1, true, ' '},
{"08", 0, false, nil, 10, 1, true, '8'},
{"08", 10, false, nat{8}, 10, 2, true, 0},
{"018", 0, false, nat{1}, 8, 1, true, '8'},
{"0b1", 0, false, nat{1}, 2, 1, true, 0},
{"0b11000101", 0, false, nat{0xc5}, 2, 8, true, 0},
{"03271", 0, false, nat{03271}, 8, 4, true, 0},
{"10ab", 0, false, nat{10}, 10, 2, true, 'a'},
{"1234567890", 0, false, nat{1234567890}, 10, 10, true, 0},
{"xyz", 36, false, nat{(33*36+34)*36 + 35}, 36, 3, true, 0},
{"xyz?", 36, false, nat{(33*36+34)*36 + 35}, 36, 3, true, '?'},
{"0x", 16, false, nil, 16, 1, true, 'x'},
{"0xdeadbeef", 0, false, nat{0xdeadbeef}, 16, 8, true, 0},
{"0XDEADBEEF", 0, false, nat{0xdeadbeef}, 16, 8, true, 0},
// no errors, decimal point
{"0.", 0, false, nil, 10, 1, true, '.'},
{"0.", 10, true, nil, 10, 0, true, 0},
{"0.1.2", 10, true, nat{1}, 10, -1, true, '.'},
{".000", 10, true, nil, 10, -3, true, 0},
{"12.3", 10, true, nat{123}, 10, -1, true, 0},
{"012.345", 10, true, nat{12345}, 10, -3, true, 0},
}
func TestScanBase(t *testing.T) {
for _, a := range natScanTests {
r := strings.NewReader(a.s)
x, b, count, err := nat(nil).scan(r, a.base, a.frac)
if err == nil && !a.ok {
t.Errorf("scan%+v\n\texpected error", a)
}
if err != nil {
if a.ok {
t.Errorf("scan%+v\n\tgot error = %s", a, err)
}
continue
}
if x.cmp(a.x) != 0 {
t.Errorf("scan%+v\n\tgot z = %v; want %v", a, x, a.x)
}
if b != a.b {
t.Errorf("scan%+v\n\tgot b = %d; want %d", a, b, a.base)
}
if count != a.count {
t.Errorf("scan%+v\n\tgot count = %d; want %d", a, count, a.count)
}
next, _, err := r.ReadRune()
if err == io.EOF {
next = 0
err = nil
}
if err == nil && next != a.next {
t.Errorf("scan%+v\n\tgot next = %q; want %q", a, next, a.next)
}
}
}
var pi = "3" +
"14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651" +
"32823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461" +
"28475648233786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920" +
"96282925409171536436789259036001133053054882046652138414695194151160943305727036575959195309218611738193261179" +
"31051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798" +
"60943702770539217176293176752384674818467669405132000568127145263560827785771342757789609173637178721468440901" +
"22495343014654958537105079227968925892354201995611212902196086403441815981362977477130996051870721134999999837" +
"29780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083" +
"81420617177669147303598253490428755468731159562863882353787593751957781857780532171226806613001927876611195909" +
"21642019893809525720106548586327886593615338182796823030195203530185296899577362259941389124972177528347913151" +
"55748572424541506959508295331168617278558890750983817546374649393192550604009277016711390098488240128583616035" +
"63707660104710181942955596198946767837449448255379774726847104047534646208046684259069491293313677028989152104" +
"75216205696602405803815019351125338243003558764024749647326391419927260426992279678235478163600934172164121992" +
"45863150302861829745557067498385054945885869269956909272107975093029553211653449872027559602364806654991198818" +
"34797753566369807426542527862551818417574672890977772793800081647060016145249192173217214772350141441973568548" +
"16136115735255213347574184946843852332390739414333454776241686251898356948556209921922218427255025425688767179" +
"04946016534668049886272327917860857843838279679766814541009538837863609506800642251252051173929848960841284886" +
"26945604241965285022210661186306744278622039194945047123713786960956364371917287467764657573962413890865832645" +
"99581339047802759009946576407895126946839835259570982582262052248940772671947826848260147699090264013639443745" +
"53050682034962524517493996514314298091906592509372216964615157098583874105978859597729754989301617539284681382" +
"68683868942774155991855925245953959431049972524680845987273644695848653836736222626099124608051243884390451244" +
"13654976278079771569143599770012961608944169486855584840635342207222582848864815845602850601684273945226746767" +
"88952521385225499546667278239864565961163548862305774564980355936345681743241125150760694794510965960940252288" +
"79710893145669136867228748940560101503308617928680920874760917824938589009714909675985261365549781893129784821" +
"68299894872265880485756401427047755513237964145152374623436454285844479526586782105114135473573952311342716610" +
"21359695362314429524849371871101457654035902799344037420073105785390621983874478084784896833214457138687519435" +
"06430218453191048481005370614680674919278191197939952061419663428754440643745123718192179998391015919561814675" +
"14269123974894090718649423196156794520809514655022523160388193014209376213785595663893778708303906979207734672" +
"21825625996615014215030680384477345492026054146659252014974428507325186660021324340881907104863317346496514539" +
"05796268561005508106658796998163574736384052571459102897064140110971206280439039759515677157700420337869936007" +
"23055876317635942187312514712053292819182618612586732157919841484882916447060957527069572209175671167229109816" +
"90915280173506712748583222871835209353965725121083579151369882091444210067510334671103141267111369908658516398" +
"31501970165151168517143765761835155650884909989859982387345528331635507647918535893226185489632132933089857064" +
"20467525907091548141654985946163718027098199430992448895757128289059232332609729971208443357326548938239119325" +
"97463667305836041428138830320382490375898524374417029132765618093773444030707469211201913020330380197621101100" +
"44929321516084244485963766983895228684783123552658213144957685726243344189303968642624341077322697802807318915" +
"44110104468232527162010526522721116603966655730925471105578537634668206531098965269186205647693125705863566201" +
"85581007293606598764861179104533488503461136576867532494416680396265797877185560845529654126654085306143444318" +
"58676975145661406800700237877659134401712749470420562230538994561314071127000407854733269939081454664645880797" +
"27082668306343285878569830523580893306575740679545716377525420211495576158140025012622859413021647155097925923" +
"09907965473761255176567513575178296664547791745011299614890304639947132962107340437518957359614589019389713111" +
"79042978285647503203198691514028708085990480109412147221317947647772622414254854540332157185306142288137585043" +
"06332175182979866223717215916077166925474873898665494945011465406284336639379003976926567214638530673609657120" +
"91807638327166416274888800786925602902284721040317211860820419000422966171196377921337575114959501566049631862" +
"94726547364252308177036751590673502350728354056704038674351362222477158915049530984448933309634087807693259939" +
"78054193414473774418426312986080998886874132604721569516239658645730216315981931951673538129741677294786724229" +
"24654366800980676928238280689964004824354037014163149658979409243237896907069779422362508221688957383798623001" +
"59377647165122893578601588161755782973523344604281512627203734314653197777416031990665541876397929334419521541" +
"34189948544473456738316249934191318148092777710386387734317720754565453220777092120190516609628049092636019759" +
"88281613323166636528619326686336062735676303544776280350450777235547105859548702790814356240145171806246436267" +
"94561275318134078330336254232783944975382437205835311477119926063813346776879695970309833913077109870408591337"
// Test case for BenchmarkScanPi.
func TestScanPi(t *testing.T) {
var x nat
z, _, _, err := x.scan(strings.NewReader(pi), 10, false)
if err != nil {
t.Errorf("scanning pi: %s", err)
}
if s := string(z.utoa(10)); s != pi {
t.Errorf("scanning pi: got %s", s)
}
}
func TestScanPiParallel(t *testing.T) {
const n = 2
c := make(chan int)
for i := 0; i < n; i++ {
go func() {
TestScanPi(t)
c <- 0
}()
}
for i := 0; i < n; i++ {
<-c
}
}
func BenchmarkScanPi(b *testing.B) {
for i := 0; i < b.N; i++ {
var x nat
x.scan(strings.NewReader(pi), 10, false)
}
}
func BenchmarkStringPiParallel(b *testing.B) {
var x nat
x, _, _, _ = x.scan(strings.NewReader(pi), 0, false)
if string(x.utoa(10)) != pi {
panic("benchmark incorrect: conversion failed")
}
b.RunParallel(func(pb *testing.PB) {
for pb.Next() {
x.utoa(10)
}
})
}
func BenchmarkScan(b *testing.B) {
const x = 10
for _, base := range []int{2, 8, 10, 16} {
for _, y := range []Word{10, 100, 1000, 10000, 100000} {
b.Run(fmt.Sprintf("%d/Base%d", y, base), func(b *testing.B) {
b.StopTimer()
var z nat
z = z.expWW(x, y)
s := z.utoa(base)
if t := itoa(z, base); !bytes.Equal(s, t) {
b.Fatalf("scanning: got %s; want %s", s, t)
}
b.StartTimer()
for i := 0; i < b.N; i++ {
z.scan(bytes.NewReader(s), base, false)
}
})
}
}
}
func BenchmarkString(b *testing.B) {
const x = 10
for _, base := range []int{2, 8, 10, 16} {
for _, y := range []Word{10, 100, 1000, 10000, 100000} {
b.Run(fmt.Sprintf("%d/Base%d", y, base), func(b *testing.B) {
b.StopTimer()
var z nat
z = z.expWW(x, y)
z.utoa(base) // warm divisor cache
b.StartTimer()
for i := 0; i < b.N; i++ {
_ = z.utoa(base)
}
})
}
}
}
func BenchmarkLeafSize(b *testing.B) {
for n := 0; n <= 16; n++ {
b.Run(fmt.Sprint(n), func(b *testing.B) { LeafSizeHelper(b, 10, n) })
}
// Try some large lengths
for _, n := range []int{32, 64} {
b.Run(fmt.Sprint(n), func(b *testing.B) { LeafSizeHelper(b, 10, n) })
}
}
func LeafSizeHelper(b *testing.B, base, size int) {
b.StopTimer()
originalLeafSize := leafSize
resetTable(cacheBase10.table[:])
leafSize = size
b.StartTimer()
for d := 1; d <= 10000; d *= 10 {
b.StopTimer()
var z nat
z = z.expWW(Word(base), Word(d)) // build target number
_ = z.utoa(base) // warm divisor cache
b.StartTimer()
for i := 0; i < b.N; i++ {
_ = z.utoa(base)
}
}
b.StopTimer()
resetTable(cacheBase10.table[:])
leafSize = originalLeafSize
b.StartTimer()
}
func resetTable(table []divisor) {
if table != nil && table[0].bbb != nil {
for i := 0; i < len(table); i++ {
table[i].bbb = nil
table[i].nbits = 0
table[i].ndigits = 0
}
}
}
func TestStringPowers(t *testing.T) {
var p Word
for b := 2; b <= 16; b++ {
for p = 0; p <= 512; p++ {
x := nat(nil).expWW(Word(b), p)
xs := x.utoa(b)
xs2 := itoa(x, b)
if !bytes.Equal(xs, xs2) {
t.Errorf("failed at %d ** %d in base %d: %s != %s", b, p, b, xs, xs2)
}
}
if b >= 3 && testing.Short() {
break
}
}
}

510
src/cmd/compile/internal/big/rat.go
View file

@ -1,510 +0,0 @@
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements multi-precision rational numbers.
package big
import (
"fmt"
"math"
)
// A Rat represents a quotient a/b of arbitrary precision.
// The zero value for a Rat represents the value 0.
type Rat struct {
// To make zero values for Rat work w/o initialization,
// a zero value of b (len(b) == 0) acts like b == 1.
// a.neg determines the sign of the Rat, b.neg is ignored.
a, b Int
}
// NewRat creates a new Rat with numerator a and denominator b.
func NewRat(a, b int64) *Rat {
return new(Rat).SetFrac64(a, b)
}
// SetFloat64 sets z to exactly f and returns z.
// If f is not finite, SetFloat returns nil.
func (z *Rat) SetFloat64(f float64) *Rat {
const expMask = 1<<11 - 1
bits := math.Float64bits(f)
mantissa := bits & (1<<52 - 1)
exp := int((bits >> 52) & expMask)
switch exp {
case expMask: // non-finite
return nil
case 0: // denormal
exp -= 1022
default: // normal
mantissa |= 1 << 52
exp -= 1023
}
shift := 52 - exp
// Optimization (?): partially pre-normalise.
for mantissa&1 == 0 && shift > 0 {
mantissa >>= 1
shift--
}
z.a.SetUint64(mantissa)
z.a.neg = f < 0
z.b.Set(intOne)
if shift > 0 {
z.b.Lsh(&z.b, uint(shift))
} else {
z.a.Lsh(&z.a, uint(-shift))
}
return z.norm()
}
// quotToFloat32 returns the non-negative float32 value
// nearest to the quotient a/b, using round-to-even in
// halfway cases. It does not mutate its arguments.
// Preconditions: b is non-zero; a and b have no common factors.
func quotToFloat32(a, b nat) (f float32, exact bool) {
const (
// float size in bits
Fsize = 32
// mantissa
Msize = 23
Msize1 = Msize + 1 // incl. implicit 1
Msize2 = Msize1 + 1
// exponent
Esize = Fsize - Msize1
Ebias = 1<<(Esize-1) - 1
Emin = 1 - Ebias
Emax = Ebias
)
// TODO(adonovan): specialize common degenerate cases: 1.0, integers.
alen := a.bitLen()
if alen == 0 {
return 0, true
}
blen := b.bitLen()
if blen == 0 {
panic("division by zero")
}
// 1. Left-shift A or B such that quotient A/B is in [1<<Msize1, 1<<(Msize2+1)
// (Msize2 bits if A < B when they are left-aligned, Msize2+1 bits if A >= B).
// This is 2 or 3 more than the float32 mantissa field width of Msize:
// - the optional extra bit is shifted away in step 3 below.
// - the high-order 1 is omitted in "normal" representation;
// - the low-order 1 will be used during rounding then discarded.
exp := alen - blen
var a2, b2 nat
a2 = a2.set(a)
b2 = b2.set(b)
if shift := Msize2 - exp; shift > 0 {
a2 = a2.shl(a2, uint(shift))
} else if shift < 0 {
b2 = b2.shl(b2, uint(-shift))
}
// 2. Compute quotient and remainder (q, r). NB: due to the
// extra shift, the low-order bit of q is logically the
// high-order bit of r.
var q nat
q, r := q.div(a2, a2, b2) // (recycle a2)
mantissa := low32(q)
haveRem := len(r) > 0 // mantissa&1 && !haveRem => remainder is exactly half
// 3. If quotient didn't fit in Msize2 bits, redo division by b2<<1
// (in effect---we accomplish this incrementally).
if mantissa>>Msize2 == 1 {
if mantissa&1 == 1 {
haveRem = true
}
mantissa >>= 1
exp++
}
if mantissa>>Msize1 != 1 {
panic(fmt.Sprintf("expected exactly %d bits of result", Msize2))
}
// 4. Rounding.
if Emin-Msize <= exp && exp <= Emin {
// Denormal case; lose 'shift' bits of precision.
shift := uint(Emin - (exp - 1)) // [1..Esize1)
lostbits := mantissa & (1<<shift - 1)
haveRem = haveRem || lostbits != 0
mantissa >>= shift
exp = 2 - Ebias // == exp + shift
}
// Round q using round-half-to-even.
exact = !haveRem
if mantissa&1 != 0 {
exact = false
if haveRem || mantissa&2 != 0 {
if mantissa++; mantissa >= 1<<Msize2 {
// Complete rollover 11...1 => 100...0, so shift is safe
mantissa >>= 1
exp++
}
}
}
mantissa >>= 1 // discard rounding bit. Mantissa now scaled by 1<<Msize1.
f = float32(math.Ldexp(float64(mantissa), exp-Msize1))
if math.IsInf(float64(f), 0) {
exact = false
}
return
}
// quotToFloat64 returns the non-negative float64 value
// nearest to the quotient a/b, using round-to-even in
// halfway cases. It does not mutate its arguments.
// Preconditions: b is non-zero; a and b have no common factors.
func quotToFloat64(a, b nat) (f float64, exact bool) {
const (
// float size in bits
Fsize = 64
// mantissa
Msize = 52
Msize1 = Msize + 1 // incl. implicit 1
Msize2 = Msize1 + 1
// exponent
Esize = Fsize - Msize1
Ebias = 1<<(Esize-1) - 1
Emin = 1 - Ebias
Emax = Ebias
)
// TODO(adonovan): specialize common degenerate cases: 1.0, integers.
alen := a.bitLen()
if alen == 0 {
return 0, true
}
blen := b.bitLen()
if blen == 0 {
panic("division by zero")
}
// 1. Left-shift A or B such that quotient A/B is in [1<<Msize1, 1<<(Msize2+1)
// (Msize2 bits if A < B when they are left-aligned, Msize2+1 bits if A >= B).
// This is 2 or 3 more than the float64 mantissa field width of Msize:
// - the optional extra bit is shifted away in step 3 below.
// - the high-order 1 is omitted in "normal" representation;
// - the low-order 1 will be used during rounding then discarded.
exp := alen - blen
var a2, b2 nat
a2 = a2.set(a)
b2 = b2.set(b)
if shift := Msize2 - exp; shift > 0 {
a2 = a2.shl(a2, uint(shift))
} else if shift < 0 {
b2 = b2.shl(b2, uint(-shift))
}
// 2. Compute quotient and remainder (q, r). NB: due to the
// extra shift, the low-order bit of q is logically the
// high-order bit of r.
var q nat
q, r := q.div(a2, a2, b2) // (recycle a2)
mantissa := low64(q)
haveRem := len(r) > 0 // mantissa&1 && !haveRem => remainder is exactly half
// 3. If quotient didn't fit in Msize2 bits, redo division by b2<<1
// (in effect---we accomplish this incrementally).
if mantissa>>Msize2 == 1 {
if mantissa&1 == 1 {
haveRem = true
}
mantissa >>= 1
exp++
}
if mantissa>>Msize1 != 1 {
panic(fmt.Sprintf("expected exactly %d bits of result", Msize2))
}
// 4. Rounding.
if Emin-Msize <= exp && exp <= Emin {
// Denormal case; lose 'shift' bits of precision.
shift := uint(Emin - (exp - 1)) // [1..Esize1)
lostbits := mantissa & (1<<shift - 1)
haveRem = haveRem || lostbits != 0
mantissa >>= shift
exp = 2 - Ebias // == exp + shift
}
// Round q using round-half-to-even.
exact = !haveRem
if mantissa&1 != 0 {
exact = false
if haveRem || mantissa&2 != 0 {
if mantissa++; mantissa >= 1<<Msize2 {
// Complete rollover 11...1 => 100...0, so shift is safe
mantissa >>= 1
exp++
}
}
}
mantissa >>= 1 // discard rounding bit. Mantissa now scaled by 1<<Msize1.
f = math.Ldexp(float64(mantissa), exp-Msize1)
if math.IsInf(f, 0) {
exact = false
}
return
}
// Float32 returns the nearest float32 value for x and a bool indicating
// whether f represents x exactly. If the magnitude of x is too large to
// be represented by a float32, f is an infinity and exact is false.
// The sign of f always matches the sign of x, even if f == 0.
func (x *Rat) Float32() (f float32, exact bool) {
b := x.b.abs
if len(b) == 0 {
b = b.set(natOne) // materialize denominator
}
f, exact = quotToFloat32(x.a.abs, b)
if x.a.neg {
f = -f
}
return
}
// Float64 returns the nearest float64 value for x and a bool indicating
// whether f represents x exactly. If the magnitude of x is too large to
// be represented by a float64, f is an infinity and exact is false.
// The sign of f always matches the sign of x, even if f == 0.
func (x *Rat) Float64() (f float64, exact bool) {
b := x.b.abs
if len(b) == 0 {
b = b.set(natOne) // materialize denominator
}
f, exact = quotToFloat64(x.a.abs, b)
if x.a.neg {
f = -f
}
return
}
// SetFrac sets z to a/b and returns z.
func (z *Rat) SetFrac(a, b *Int) *Rat {
z.a.neg = a.neg != b.neg
babs := b.abs
if len(babs) == 0 {
panic("division by zero")
}
if &z.a == b || alias(z.a.abs, babs) {
babs = nat(nil).set(babs) // make a copy
}
z.a.abs = z.a.abs.set(a.abs)
z.b.abs = z.b.abs.set(babs)
return z.norm()
}
// SetFrac64 sets z to a/b and returns z.
func (z *Rat) SetFrac64(a, b int64) *Rat {
z.a.SetInt64(a)
if b == 0 {
panic("division by zero")
}
if b < 0 {
b = -b
z.a.neg = !z.a.neg
}
z.b.abs = z.b.abs.setUint64(uint64(b))
return z.norm()
}
// SetInt sets z to x (by making a copy of x) and returns z.
func (z *Rat) SetInt(x *Int) *Rat {
z.a.Set(x)
z.b.abs = z.b.abs[:0]
return z
}
// SetInt64 sets z to x and returns z.
func (z *Rat) SetInt64(x int64) *Rat {
z.a.SetInt64(x)
z.b.abs = z.b.abs[:0]
return z
}
// Set sets z to x (by making a copy of x) and returns z.
func (z *Rat) Set(x *Rat) *Rat {
if z != x {
z.a.Set(&x.a)
z.b.Set(&x.b)
}
return z
}
// Abs sets z to |x| (the absolute value of x) and returns z.
func (z *Rat) Abs(x *Rat) *Rat {
z.Set(x)
z.a.neg = false
return z
}
// Neg sets z to -x and returns z.
func (z *Rat) Neg(x *Rat) *Rat {
z.Set(x)
z.a.neg = len(z.a.abs) > 0 && !z.a.neg // 0 has no sign
return z
}
// Inv sets z to 1/x and returns z.
func (z *Rat) Inv(x *Rat) *Rat {
if len(x.a.abs) == 0 {
panic("division by zero")
}
z.Set(x)
a := z.b.abs
if len(a) == 0 {
a = a.set(natOne) // materialize numerator
}
b := z.a.abs
if b.cmp(natOne) == 0 {
b = b[:0] // normalize denominator
}
z.a.abs, z.b.abs = a, b // sign doesn't change
return z
}
// Sign returns:
//
// -1 if x < 0
// 0 if x == 0
// +1 if x > 0
//
func (x *Rat) Sign() int {
return x.a.Sign()
}
// IsInt reports whether the denominator of x is 1.
func (x *Rat) IsInt() bool {
return len(x.b.abs) == 0 || x.b.abs.cmp(natOne) == 0
}
// Num returns the numerator of x; it may be <= 0.
// The result is a reference to x's numerator; it
// may change if a new value is assigned to x, and vice versa.
// The sign of the numerator corresponds to the sign of x.
func (x *Rat) Num() *Int {
return &x.a
}
// Denom returns the denominator of x; it is always > 0.
// The result is a reference to x's denominator; it
// may change if a new value is assigned to x, and vice versa.
func (x *Rat) Denom() *Int {
x.b.neg = false // the result is always >= 0
if len(x.b.abs) == 0 {
x.b.abs = x.b.abs.set(natOne) // materialize denominator
}
return &x.b
}
func (z *Rat) norm() *Rat {
switch {
case len(z.a.abs) == 0:
// z == 0 - normalize sign and denominator
z.a.neg = false
z.b.abs = z.b.abs[:0]
case len(z.b.abs) == 0:
// z is normalized int - nothing to do
case z.b.abs.cmp(natOne) == 0:
// z is int - normalize denominator
z.b.abs = z.b.abs[:0]
default:
neg := z.a.neg
z.a.neg = false
z.b.neg = false
if f := NewInt(0).binaryGCD(&z.a, &z.b); f.Cmp(intOne) != 0 {
z.a.abs, _ = z.a.abs.div(nil, z.a.abs, f.abs)
z.b.abs, _ = z.b.abs.div(nil, z.b.abs, f.abs)
if z.b.abs.cmp(natOne) == 0 {
// z is int - normalize denominator
z.b.abs = z.b.abs[:0]
}
}
z.a.neg = neg
}
return z
}
// mulDenom sets z to the denominator product x*y (by taking into
// account that 0 values for x or y must be interpreted as 1) and
// returns z.
func mulDenom(z, x, y nat) nat {
switch {
case len(x) == 0:
return z.set(y)
case len(y) == 0:
return z.set(x)
}
return z.mul(x, y)
}
// scaleDenom computes x*f.
// If f == 0 (zero value of denominator), the result is (a copy of) x.
func scaleDenom(x *Int, f nat) *Int {
var z Int
if len(f) == 0 {
return z.Set(x)
}
z.abs = z.abs.mul(x.abs, f)
z.neg = x.neg
return &z
}
// Cmp compares x and y and returns:
//
// -1 if x < y
// 0 if x == y
// +1 if x > y
//
func (x *Rat) Cmp(y *Rat) int {
return scaleDenom(&x.a, y.b.abs).Cmp(scaleDenom(&y.a, x.b.abs))
}
// Add sets z to the sum x+y and returns z.
func (z *Rat) Add(x, y *Rat) *Rat {
a1 := scaleDenom(&x.a, y.b.abs)
a2 := scaleDenom(&y.a, x.b.abs)
z.a.Add(a1, a2)
z.b.abs = mulDenom(z.b.abs, x.b.abs, y.b.abs)
return z.norm()
}
// Sub sets z to the difference x-y and returns z.
func (z *Rat) Sub(x, y *Rat) *Rat {
a1 := scaleDenom(&x.a, y.b.abs)
a2 := scaleDenom(&y.a, x.b.abs)
z.a.Sub(a1, a2)
z.b.abs = mulDenom(z.b.abs, x.b.abs, y.b.abs)
return z.norm()
}
// Mul sets z to the product x*y and returns z.
func (z *Rat) Mul(x, y *Rat) *Rat {
z.a.Mul(&x.a, &y.a)
z.b.abs = mulDenom(z.b.abs, x.b.abs, y.b.abs)
return z.norm()
}
// Quo sets z to the quotient x/y and returns z.
// If y == 0, a division-by-zero run-time panic occurs.
func (z *Rat) Quo(x, y *Rat) *Rat {
if len(y.a.abs) == 0 {
panic("division by zero")
}
a := scaleDenom(&x.a, y.b.abs)
b := scaleDenom(&y.a, x.b.abs)
z.a.abs = a.abs
z.b.abs = b.abs
z.a.neg = a.neg != b.neg
return z.norm()
}

622
src/cmd/compile/internal/big/rat_test.go
View file

@ -1,622 +0,0 @@
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"math"
"testing"
)
func TestZeroRat(t *testing.T) {
var x, y, z Rat
y.SetFrac64(0, 42)
if x.Cmp(&y) != 0 {
t.Errorf("x and y should be both equal and zero")
}
if s := x.String(); s != "0/1" {
t.Errorf("got x = %s, want 0/1", s)
}
if s := x.RatString(); s != "0" {
t.Errorf("got x = %s, want 0", s)
}
z.Add(&x, &y)
if s := z.RatString(); s != "0" {
t.Errorf("got x+y = %s, want 0", s)
}
z.Sub(&x, &y)
if s := z.RatString(); s != "0" {
t.Errorf("got x-y = %s, want 0", s)
}
z.Mul(&x, &y)
if s := z.RatString(); s != "0" {
t.Errorf("got x*y = %s, want 0", s)
}
// check for division by zero
defer func() {
if s := recover(); s == nil || s.(string) != "division by zero" {
panic(s)
}
}()
z.Quo(&x, &y)
}
func TestRatSign(t *testing.T) {
zero := NewRat(0, 1)
for _, a := range setStringTests {
x, ok := new(Rat).SetString(a.in)
if !ok {
continue
}
s := x.Sign()
e := x.Cmp(zero)
if s != e {
t.Errorf("got %d; want %d for z = %v", s, e, &x)
}
}
}
var ratCmpTests = []struct {
rat1, rat2 string
out int
}{
{"0", "0/1", 0},
{"1/1", "1", 0},
{"-1", "-2/2", 0},
{"1", "0", 1},
{"0/1", "1/1", -1},
{"-5/1434770811533343057144", "-5/1434770811533343057145", -1},
{"49832350382626108453/8964749413", "49832350382626108454/8964749413", -1},
{"-37414950961700930/7204075375675961", "37414950961700930/7204075375675961", -1},
{"37414950961700930/7204075375675961", "74829901923401860/14408150751351922", 0},
}
func TestRatCmp(t *testing.T) {
for i, test := range ratCmpTests {
x, _ := new(Rat).SetString(test.rat1)
y, _ := new(Rat).SetString(test.rat2)
out := x.Cmp(y)
if out != test.out {
t.Errorf("#%d got out = %v; want %v", i, out, test.out)
}
}
}
func TestIsInt(t *testing.T) {
one := NewInt(1)
for _, a := range setStringTests {
x, ok := new(Rat).SetString(a.in)
if !ok {
continue
}
i := x.IsInt()
e := x.Denom().Cmp(one) == 0
if i != e {
t.Errorf("got IsInt(%v) == %v; want %v", x, i, e)
}
}
}
func TestRatAbs(t *testing.T) {
zero := new(Rat)
for _, a := range setStringTests {
x, ok := new(Rat).SetString(a.in)
if !ok {
continue
}
e := new(Rat).Set(x)
if e.Cmp(zero) < 0 {
e.Sub(zero, e)
}
z := new(Rat).Abs(x)
if z.Cmp(e) != 0 {
t.Errorf("got Abs(%v) = %v; want %v", x, z, e)
}
}
}
func TestRatNeg(t *testing.T) {
zero := new(Rat)
for _, a := range setStringTests {
x, ok := new(Rat).SetString(a.in)
if !ok {
continue
}
e := new(Rat).Sub(zero, x)
z := new(Rat).Neg(x)
if z.Cmp(e) != 0 {
t.Errorf("got Neg(%v) = %v; want %v", x, z, e)
}
}
}
func TestRatInv(t *testing.T) {
zero := new(Rat)
for _, a := range setStringTests {
x, ok := new(Rat).SetString(a.in)
if !ok {
continue
}
if x.Cmp(zero) == 0 {
continue // avoid division by zero
}
e := new(Rat).SetFrac(x.Denom(), x.Num())
z := new(Rat).Inv(x)
if z.Cmp(e) != 0 {
t.Errorf("got Inv(%v) = %v; want %v", x, z, e)
}
}
}
type ratBinFun func(z, x, y *Rat) *Rat
type ratBinArg struct {
x, y, z string
}
func testRatBin(t *testing.T, i int, name string, f ratBinFun, a ratBinArg) {
x, _ := new(Rat).SetString(a.x)
y, _ := new(Rat).SetString(a.y)
z, _ := new(Rat).SetString(a.z)
out := f(new(Rat), x, y)
if out.Cmp(z) != 0 {
t.Errorf("%s #%d got %s want %s", name, i, out, z)
}
}
var ratBinTests = []struct {
x, y string
sum, prod string
}{
{"0", "0", "0", "0"},
{"0", "1", "1", "0"},
{"-1", "0", "-1", "0"},
{"-1", "1", "0", "-1"},
{"1", "1", "2", "1"},
{"1/2", "1/2", "1", "1/4"},
{"1/4", "1/3", "7/12", "1/12"},
{"2/5", "-14/3", "-64/15", "-28/15"},
{"4707/49292519774798173060", "-3367/70976135186689855734", "84058377121001851123459/1749296273614329067191168098769082663020", "-1760941/388732505247628681598037355282018369560"},
{"-61204110018146728334/3", "-31052192278051565633/2", "-215564796870448153567/6", "950260896245257153059642991192710872711/3"},
{"-854857841473707320655/4237645934602118692642972629634714039", "-18/31750379913563777419", "-27/133467566250814981", "15387441146526731771790/134546868362786310073779084329032722548987800600710485341"},
{"618575745270541348005638912139/19198433543745179392300736", "-19948846211000086/637313996471", "27674141753240653/30123979153216", "-6169936206128396568797607742807090270137721977/6117715203873571641674006593837351328"},
{"-3/26206484091896184128", "5/2848423294177090248", "15310893822118706237/9330894968229805033368778458685147968", "-5/24882386581946146755650075889827061248"},
{"26946729/330400702820", "41563965/225583428284", "1238218672302860271/4658307703098666660055", "224002580204097/14906584649915733312176"},
{"-8259900599013409474/7", "-84829337473700364773/56707961321161574960", "-468402123685491748914621885145127724451/396955729248131024720", "350340947706464153265156004876107029701/198477864624065512360"},
{"575775209696864/1320203974639986246357", "29/712593081308", "410331716733912717985762465/940768218243776489278275419794956", "808/45524274987585732633"},
{"1786597389946320496771/2066653520653241", "6269770/1992362624741777", "3559549865190272133656109052308126637/4117523232840525481453983149257", "8967230/3296219033"},
{"-36459180403360509753/32150500941194292113930", "9381566963714/9633539", "301622077145533298008420642898530153/309723104686531919656937098270", "-3784609207827/3426986245"},
}
func TestRatBin(t *testing.T) {
for i, test := range ratBinTests {
arg := ratBinArg{test.x, test.y, test.sum}
testRatBin(t, i, "Add", (*Rat).Add, arg)
arg = ratBinArg{test.y, test.x, test.sum}
testRatBin(t, i, "Add symmetric", (*Rat).Add, arg)
arg = ratBinArg{test.sum, test.x, test.y}
testRatBin(t, i, "Sub", (*Rat).Sub, arg)
arg = ratBinArg{test.sum, test.y, test.x}
testRatBin(t, i, "Sub symmetric", (*Rat).Sub, arg)
arg = ratBinArg{test.x, test.y, test.prod}
testRatBin(t, i, "Mul", (*Rat).Mul, arg)
arg = ratBinArg{test.y, test.x, test.prod}
testRatBin(t, i, "Mul symmetric", (*Rat).Mul, arg)
if test.x != "0" {
arg = ratBinArg{test.prod, test.x, test.y}
testRatBin(t, i, "Quo", (*Rat).Quo, arg)
}
if test.y != "0" {
arg = ratBinArg{test.prod, test.y, test.x}
testRatBin(t, i, "Quo symmetric", (*Rat).Quo, arg)
}
}
}
func TestIssue820(t *testing.T) {
x := NewRat(3, 1)
y := NewRat(2, 1)
z := y.Quo(x, y)
q := NewRat(3, 2)
if z.Cmp(q) != 0 {
t.Errorf("got %s want %s", z, q)
}
y = NewRat(3, 1)
x = NewRat(2, 1)
z = y.Quo(x, y)
q = NewRat(2, 3)
if z.Cmp(q) != 0 {
t.Errorf("got %s want %s", z, q)
}
x = NewRat(3, 1)
z = x.Quo(x, x)
q = NewRat(3, 3)
if z.Cmp(q) != 0 {
t.Errorf("got %s want %s", z, q)
}
}
var setFrac64Tests = []struct {
a, b int64
out string
}{
{0, 1, "0"},
{0, -1, "0"},
{1, 1, "1"},
{-1, 1, "-1"},
{1, -1, "-1"},
{-1, -1, "1"},
{-9223372036854775808, -9223372036854775808, "1"},
}
func TestRatSetFrac64Rat(t *testing.T) {
for i, test := range setFrac64Tests {
x := new(Rat).SetFrac64(test.a, test.b)
if x.RatString() != test.out {
t.Errorf("#%d got %s want %s", i, x.RatString(), test.out)
}
}
}
func TestIssue2379(t *testing.T) {
// 1) no aliasing
q := NewRat(3, 2)
x := new(Rat)
x.SetFrac(NewInt(3), NewInt(2))
if x.Cmp(q) != 0 {
t.Errorf("1) got %s want %s", x, q)
}
// 2) aliasing of numerator
x = NewRat(2, 3)
x.SetFrac(NewInt(3), x.Num())
if x.Cmp(q) != 0 {
t.Errorf("2) got %s want %s", x, q)
}
// 3) aliasing of denominator
x = NewRat(2, 3)
x.SetFrac(x.Denom(), NewInt(2))
if x.Cmp(q) != 0 {
t.Errorf("3) got %s want %s", x, q)
}
// 4) aliasing of numerator and denominator
x = NewRat(2, 3)
x.SetFrac(x.Denom(), x.Num())
if x.Cmp(q) != 0 {
t.Errorf("4) got %s want %s", x, q)
}
// 5) numerator and denominator are the same
q = NewRat(1, 1)
x = new(Rat)
n := NewInt(7)
x.SetFrac(n, n)
if x.Cmp(q) != 0 {
t.Errorf("5) got %s want %s", x, q)
}
}
func TestIssue3521(t *testing.T) {
a := new(Int)
b := new(Int)
a.SetString("64375784358435883458348587", 0)
b.SetString("4789759874531", 0)
// 0) a raw zero value has 1 as denominator
zero := new(Rat)
one := NewInt(1)
if zero.Denom().Cmp(one) != 0 {
t.Errorf("0) got %s want %s", zero.Denom(), one)
}
// 1a) a zero value remains zero independent of denominator
x := new(Rat)
x.Denom().Set(new(Int).Neg(b))
if x.Cmp(zero) != 0 {
t.Errorf("1a) got %s want %s", x, zero)
}
// 1b) a zero value may have a denominator != 0 and != 1
x.Num().Set(a)
qab := new(Rat).SetFrac(a, b)
if x.Cmp(qab) != 0 {
t.Errorf("1b) got %s want %s", x, qab)
}
// 2a) an integral value becomes a fraction depending on denominator
x.SetFrac64(10, 2)
x.Denom().SetInt64(3)
q53 := NewRat(5, 3)
if x.Cmp(q53) != 0 {
t.Errorf("2a) got %s want %s", x, q53)
}
// 2b) an integral value becomes a fraction depending on denominator
x = NewRat(10, 2)
x.Denom().SetInt64(3)
if x.Cmp(q53) != 0 {
t.Errorf("2b) got %s want %s", x, q53)
}
// 3) changing the numerator/denominator of a Rat changes the Rat
x.SetFrac(a, b)
a = x.Num()
b = x.Denom()
a.SetInt64(5)
b.SetInt64(3)
if x.Cmp(q53) != 0 {
t.Errorf("3) got %s want %s", x, q53)
}
}
func TestFloat32Distribution(t *testing.T) {
// Generate a distribution of (sign, mantissa, exp) values
// broader than the float32 range, and check Rat.Float32()
// always picks the closest float32 approximation.
var add = []int64{
0,
1,
3,
5,
7,
9,
11,
}
var winc, einc = uint64(1), 1 // soak test (~1.5s on x86-64)
if testing.Short() {
winc, einc = 5, 15 // quick test (~60ms on x86-64)
}
for _, sign := range "+-" {
for _, a := range add {
for wid := uint64(0); wid < 30; wid += winc {
b := 1<<wid + a
if sign == '-' {
b = -b
}
for exp := -150; exp < 150; exp += einc {
num, den := NewInt(b), NewInt(1)
if exp > 0 {
num.Lsh(num, uint(exp))
} else {
den.Lsh(den, uint(-exp))
}
r := new(Rat).SetFrac(num, den)
f, _ := r.Float32()
if !checkIsBestApprox32(t, f, r) {
// Append context information.
t.Errorf("(input was mantissa %#x, exp %d; f = %g (%b); f ~ %g; r = %v)",
b, exp, f, f, math.Ldexp(float64(b), exp), r)
}
checkNonLossyRoundtrip32(t, f)
}
}
}
}
}
func TestFloat64Distribution(t *testing.T) {
// Generate a distribution of (sign, mantissa, exp) values
// broader than the float64 range, and check Rat.Float64()
// always picks the closest float64 approximation.
var add = []int64{
0,
1,
3,
5,
7,
9,
11,
}
var winc, einc = uint64(1), 1 // soak test (~75s on x86-64)
if testing.Short() {
winc, einc = 10, 500 // quick test (~12ms on x86-64)
}
for _, sign := range "+-" {
for _, a := range add {
for wid := uint64(0); wid < 60; wid += winc {
b := 1<<wid + a
if sign == '-' {
b = -b
}
for exp := -1100; exp < 1100; exp += einc {
num, den := NewInt(b), NewInt(1)
if exp > 0 {
num.Lsh(num, uint(exp))
} else {
den.Lsh(den, uint(-exp))
}
r := new(Rat).SetFrac(num, den)
f, _ := r.Float64()
if !checkIsBestApprox64(t, f, r) {
// Append context information.
t.Errorf("(input was mantissa %#x, exp %d; f = %g (%b); f ~ %g; r = %v)",
b, exp, f, f, math.Ldexp(float64(b), exp), r)
}
checkNonLossyRoundtrip64(t, f)
}
}
}
}
}
// TestSetFloat64NonFinite checks that SetFloat64 of a non-finite value
// returns nil.
func TestSetFloat64NonFinite(t *testing.T) {
for _, f := range []float64{math.NaN(), math.Inf(+1), math.Inf(-1)} {
var r Rat
if r2 := r.SetFloat64(f); r2 != nil {
t.Errorf("SetFloat64(%g) was %v, want nil", f, r2)
}
}
}
// checkNonLossyRoundtrip32 checks that a float->Rat->float roundtrip is
// non-lossy for finite f.
func checkNonLossyRoundtrip32(t *testing.T, f float32) {
if !isFinite(float64(f)) {
return
}
r := new(Rat).SetFloat64(float64(f))
if r == nil {
t.Errorf("Rat.SetFloat64(float64(%g) (%b)) == nil", f, f)
return
}
f2, exact := r.Float32()
if f != f2 || !exact {
t.Errorf("Rat.SetFloat64(float64(%g)).Float32() = %g (%b), %v, want %g (%b), %v; delta = %b",
f, f2, f2, exact, f, f, true, f2-f)
}
}
// checkNonLossyRoundtrip64 checks that a float->Rat->float roundtrip is
// non-lossy for finite f.
func checkNonLossyRoundtrip64(t *testing.T, f float64) {
if !isFinite(f) {
return
}
r := new(Rat).SetFloat64(f)
if r == nil {
t.Errorf("Rat.SetFloat64(%g (%b)) == nil", f, f)
return
}
f2, exact := r.Float64()
if f != f2 || !exact {
t.Errorf("Rat.SetFloat64(%g).Float64() = %g (%b), %v, want %g (%b), %v; delta = %b",
f, f2, f2, exact, f, f, true, f2-f)
}
}
// delta returns the absolute difference between r and f.
func delta(r *Rat, f float64) *Rat {
d := new(Rat).Sub(r, new(Rat).SetFloat64(f))
return d.Abs(d)
}
// checkIsBestApprox32 checks that f is the best possible float32
// approximation of r.
// Returns true on success.
func checkIsBestApprox32(t *testing.T, f float32, r *Rat) bool {
if math.Abs(float64(f)) >= math.MaxFloat32 {
// Cannot check +Inf, -Inf, nor the float next to them (MaxFloat32).
// But we have tests for these special cases.
return true
}
// r must be strictly between f0 and f1, the floats bracketing f.
f0 := math.Nextafter32(f, float32(math.Inf(-1)))
f1 := math.Nextafter32(f, float32(math.Inf(+1)))
// For f to be correct, r must be closer to f than to f0 or f1.
df := delta(r, float64(f))
df0 := delta(r, float64(f0))
df1 := delta(r, float64(f1))
if df.Cmp(df0) > 0 {
t.Errorf("Rat(%v).Float32() = %g (%b), but previous float32 %g (%b) is closer", r, f, f, f0, f0)
return false
}
if df.Cmp(df1) > 0 {
t.Errorf("Rat(%v).Float32() = %g (%b), but next float32 %g (%b) is closer", r, f, f, f1, f1)
return false
}
if df.Cmp(df0) == 0 && !isEven32(f) {
t.Errorf("Rat(%v).Float32() = %g (%b); halfway should have rounded to %g (%b) instead", r, f, f, f0, f0)
return false
}
if df.Cmp(df1) == 0 && !isEven32(f) {
t.Errorf("Rat(%v).Float32() = %g (%b); halfway should have rounded to %g (%b) instead", r, f, f, f1, f1)
return false
}
return true
}
// checkIsBestApprox64 checks that f is the best possible float64
// approximation of r.
// Returns true on success.
func checkIsBestApprox64(t *testing.T, f float64, r *Rat) bool {
if math.Abs(f) >= math.MaxFloat64 {
// Cannot check +Inf, -Inf, nor the float next to them (MaxFloat64).
// But we have tests for these special cases.
return true
}
// r must be strictly between f0 and f1, the floats bracketing f.
f0 := math.Nextafter(f, math.Inf(-1))
f1 := math.Nextafter(f, math.Inf(+1))
// For f to be correct, r must be closer to f than to f0 or f1.
df := delta(r, f)
df0 := delta(r, f0)
df1 := delta(r, f1)
if df.Cmp(df0) > 0 {
t.Errorf("Rat(%v).Float64() = %g (%b), but previous float64 %g (%b) is closer", r, f, f, f0, f0)
return false
}
if df.Cmp(df1) > 0 {
t.Errorf("Rat(%v).Float64() = %g (%b), but next float64 %g (%b) is closer", r, f, f, f1, f1)
return false
}
if df.Cmp(df0) == 0 && !isEven64(f) {
t.Errorf("Rat(%v).Float64() = %g (%b); halfway should have rounded to %g (%b) instead", r, f, f, f0, f0)
return false
}
if df.Cmp(df1) == 0 && !isEven64(f) {
t.Errorf("Rat(%v).Float64() = %g (%b); halfway should have rounded to %g (%b) instead", r, f, f, f1, f1)
return false
}
return true
}
func isEven32(f float32) bool { return math.Float32bits(f)&1 == 0 }
func isEven64(f float64) bool { return math.Float64bits(f)&1 == 0 }
func TestIsFinite(t *testing.T) {
finites := []float64{
1.0 / 3,
4891559871276714924261e+222,
math.MaxFloat64,
math.SmallestNonzeroFloat64,
-math.MaxFloat64,
-math.SmallestNonzeroFloat64,
}
for _, f := range finites {
if !isFinite(f) {
t.Errorf("!IsFinite(%g (%b))", f, f)
}
}
nonfinites := []float64{
math.NaN(),
math.Inf(-1),
math.Inf(+1),
}
for _, f := range nonfinites {
if isFinite(f) {
t.Errorf("IsFinite(%g, (%b))", f, f)
}
}
}

270
src/cmd/compile/internal/big/ratconv.go
View file

@ -1,270 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements rat-to-string conversion functions.
package big
import (
"errors"
"fmt"
"io"
"strconv"
"strings"
)
func ratTok(ch rune) bool {
return strings.ContainsRune("+-/0123456789.eE", ch)
}
// Scan is a support routine for fmt.Scanner. It accepts the formats
// 'e', 'E', 'f', 'F', 'g', 'G', and 'v'. All formats are equivalent.
func (z *Rat) Scan(s fmt.ScanState, ch rune) error {
tok, err := s.Token(true, ratTok)
if err != nil {
return err
}
if !strings.ContainsRune("efgEFGv", ch) {
return errors.New("Rat.Scan: invalid verb")
}
if _, ok := z.SetString(string(tok)); !ok {
return errors.New("Rat.Scan: invalid syntax")
}
return nil
}
// SetString sets z to the value of s and returns z and a boolean indicating
// success. s can be given as a fraction "a/b" or as a floating-point number
// optionally followed by an exponent. If the operation failed, the value of
// z is undefined but the returned value is nil.
func (z *Rat) SetString(s string) (*Rat, bool) {
if len(s) == 0 {
return nil, false
}
// len(s) > 0
// parse fraction a/b, if any
if sep := strings.Index(s, "/"); sep >= 0 {
if _, ok := z.a.SetString(s[:sep], 0); !ok {
return nil, false
}
s = s[sep+1:]
var err error
if z.b.abs, _, _, err = z.b.abs.scan(strings.NewReader(s), 0, false); err != nil {
return nil, false
}
if len(z.b.abs) == 0 {
return nil, false
}
return z.norm(), true
}
// parse floating-point number
r := strings.NewReader(s)
// sign
neg, err := scanSign(r)
if err != nil {
return nil, false
}
// mantissa
var ecorr int
z.a.abs, _, ecorr, err = z.a.abs.scan(r, 10, true)
if err != nil {
return nil, false
}
// exponent
var exp int64
exp, _, err = scanExponent(r, false)
if err != nil {
return nil, false
}
// there should be no unread characters left
if _, err = r.ReadByte(); err != io.EOF {
return nil, false
}
// special-case 0 (see also issue #16176)
if len(z.a.abs) == 0 {
return z, true
}
// len(z.a.abs) > 0
// correct exponent
if ecorr < 0 {
exp += int64(ecorr)
}
// compute exponent power
expabs := exp
if expabs < 0 {
expabs = -expabs
}
powTen := nat(nil).expNN(natTen, nat(nil).setWord(Word(expabs)), nil)
// complete fraction
if exp < 0 {
z.b.abs = powTen
z.norm()
} else {
z.a.abs = z.a.abs.mul(z.a.abs, powTen)
z.b.abs = z.b.abs[:0]
}
z.a.neg = neg && len(z.a.abs) > 0 // 0 has no sign
return z, true
}
// scanExponent scans the longest possible prefix of r representing a decimal
// ('e', 'E') or binary ('p') exponent, if any. It returns the exponent, the
// exponent base (10 or 2), or a read or syntax error, if any.
//
// exponent = ( "E" | "e" | "p" ) [ sign ] digits .
// sign = "+" | "-" .
// digits = digit { digit } .
// digit = "0" ... "9" .
//
// A binary exponent is only permitted if binExpOk is set.
func scanExponent(r io.ByteScanner, binExpOk bool) (exp int64, base int, err error) {
base = 10
var ch byte
if ch, err = r.ReadByte(); err != nil {
if err == io.EOF {
err = nil // no exponent; same as e0
}
return
}
switch ch {
case 'e', 'E':
// ok
case 'p':
if binExpOk {
base = 2
break // ok
}
fallthrough // binary exponent not permitted
default:
r.UnreadByte()
return // no exponent; same as e0
}
var neg bool
if neg, err = scanSign(r); err != nil {
return
}
var digits []byte
if neg {
digits = append(digits, '-')
}
// no need to use nat.scan for exponent digits
// since we only care about int64 values - the
// from-scratch scan is easy enough and faster
for i := 0; ; i++ {
if ch, err = r.ReadByte(); err != nil {
if err != io.EOF || i == 0 {
return
}
err = nil
break // i > 0
}
if ch < '0' || '9' < ch {
if i == 0 {
r.UnreadByte()
err = fmt.Errorf("invalid exponent (missing digits)")
return
}
break // i > 0
}
digits = append(digits, ch)
}
// i > 0 => we have at least one digit
exp, err = strconv.ParseInt(string(digits), 10, 64)
return
}
// String returns a string representation of x in the form "a/b" (even if b == 1).
func (x *Rat) String() string {
var buf []byte
buf = x.a.Append(buf, 10)
buf = append(buf, '/')
if len(x.b.abs) != 0 {
buf = x.b.Append(buf, 10)
} else {
buf = append(buf, '1')
}
return string(buf)
}
// RatString returns a string representation of x in the form "a/b" if b != 1,
// and in the form "a" if b == 1.
func (x *Rat) RatString() string {
if x.IsInt() {
return x.a.String()
}
return x.String()
}
// FloatString returns a string representation of x in decimal form with prec
// digits of precision after the decimal point. The last digit is rounded to
// nearest, with halves rounded away from zero.
func (x *Rat) FloatString(prec int) string {
var buf []byte
if x.IsInt() {
buf = x.a.Append(buf, 10)
if prec > 0 {
buf = append(buf, '.')
for i := prec; i > 0; i-- {
buf = append(buf, '0')
}
}
return string(buf)
}
// x.b.abs != 0
q, r := nat(nil).div(nat(nil), x.a.abs, x.b.abs)
p := natOne
if prec > 0 {
p = nat(nil).expNN(natTen, nat(nil).setUint64(uint64(prec)), nil)
}
r = r.mul(r, p)
r, r2 := r.div(nat(nil), r, x.b.abs)
// see if we need to round up
r2 = r2.add(r2, r2)
if x.b.abs.cmp(r2) <= 0 {
r = r.add(r, natOne)
if r.cmp(p) >= 0 {
q = nat(nil).add(q, natOne)
r = nat(nil).sub(r, p)
}
}
if x.a.neg {
buf = append(buf, '-')
}
buf = append(buf, q.utoa(10)...) // itoa ignores sign if q == 0
if prec > 0 {
buf = append(buf, '.')
rs := r.utoa(10)
for i := prec - len(rs); i > 0; i-- {
buf = append(buf, '0')
}
buf = append(buf, rs...)
}
return string(buf)
}

454
src/cmd/compile/internal/big/ratconv_test.go
View file

@ -1,454 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"bytes"
"fmt"
"math"
"strconv"
"strings"
"testing"
)
type StringTest struct {
in, out string
ok bool
}
var setStringTests = []StringTest{
{"0", "0", true},
{"-0", "0", true},
{"1", "1", true},
{"-1", "-1", true},
{"1.", "1", true},
{"1e0", "1", true},
{"1.e1", "10", true},
{in: "1e"},
{in: "1.e"},
{in: "1e+14e-5"},
{in: "1e4.5"},
{in: "r"},
{in: "a/b"},
{in: "a.b"},
{"-0.1", "-1/10", true},
{"-.1", "-1/10", true},
{"2/4", "1/2", true},
{".25", "1/4", true},
{"-1/5", "-1/5", true},
{"8129567.7690E14", "812956776900000000000", true},
{"78189e+4", "781890000", true},
{"553019.8935e+8", "55301989350000", true},
{"98765432109876543210987654321e-10", "98765432109876543210987654321/10000000000", true},
{"9877861857500000E-7", "3951144743/4", true},
{"2169378.417e-3", "2169378417/1000000", true},
{"884243222337379604041632732738665534", "884243222337379604041632732738665534", true},
{"53/70893980658822810696", "53/70893980658822810696", true},
{"106/141787961317645621392", "53/70893980658822810696", true},
{"204211327800791583.81095", "4084226556015831676219/20000", true},
{"0e9999999999", "0", true}, // issue #16176
{in: "1/0"},
}
// These are not supported by fmt.Fscanf.
var setStringTests2 = []StringTest{
{"0x10", "16", true},
{"-010/1", "-8", true}, // TODO(gri) should we even permit octal here?
{"-010.", "-10", true},
{"0x10/0x20", "1/2", true},
{"0b1000/3", "8/3", true},
// TODO(gri) add more tests
}
func TestRatSetString(t *testing.T) {
var tests []StringTest
tests = append(tests, setStringTests...)
tests = append(tests, setStringTests2...)
for i, test := range tests {
x, ok := new(Rat).SetString(test.in)
if ok {
if !test.ok {
t.Errorf("#%d SetString(%q) expected failure", i, test.in)
} else if x.RatString() != test.out {
t.Errorf("#%d SetString(%q) got %s want %s", i, test.in, x.RatString(), test.out)
}
} else if x != nil {
t.Errorf("#%d SetString(%q) got %p want nil", i, test.in, x)
}
}
}
func TestRatScan(t *testing.T) {
var buf bytes.Buffer
for i, test := range setStringTests {
x := new(Rat)
buf.Reset()
buf.WriteString(test.in)
_, err := fmt.Fscanf(&buf, "%v", x)
if err == nil != test.ok {
if test.ok {
t.Errorf("#%d (%s) error: %s", i, test.in, err)
} else {
t.Errorf("#%d (%s) expected error", i, test.in)
}
continue
}
if err == nil && x.RatString() != test.out {
t.Errorf("#%d got %s want %s", i, x.RatString(), test.out)
}
}
}
var floatStringTests = []struct {
in string
prec int
out string
}{
{"0", 0, "0"},
{"0", 4, "0.0000"},
{"1", 0, "1"},
{"1", 2, "1.00"},
{"-1", 0, "-1"},
{"0.05", 1, "0.1"},
{"-0.05", 1, "-0.1"},
{".25", 2, "0.25"},
{".25", 1, "0.3"},
{".25", 3, "0.250"},
{"-1/3", 3, "-0.333"},
{"-2/3", 4, "-0.6667"},
{"0.96", 1, "1.0"},
{"0.999", 2, "1.00"},
{"0.9", 0, "1"},
{".25", -1, "0"},
{".55", -1, "1"},
}
func TestFloatString(t *testing.T) {
for i, test := range floatStringTests {
x, _ := new(Rat).SetString(test.in)
if x.FloatString(test.prec) != test.out {
t.Errorf("#%d got %s want %s", i, x.FloatString(test.prec), test.out)
}
}
}
// Test inputs to Rat.SetString. The prefix "long:" causes the test
// to be skipped in --test.short mode. (The threshold is about 500us.)
var float64inputs = []string{
// Constants plundered from strconv/testfp.txt.
// Table 1: Stress Inputs for Conversion to 53-bit Binary, < 1/2 ULP
"5e+125",
"69e+267",
"999e-026",
"7861e-034",
"75569e-254",
"928609e-261",
"9210917e+080",
"84863171e+114",
"653777767e+273",
"5232604057e-298",
"27235667517e-109",
"653532977297e-123",
"3142213164987e-294",
"46202199371337e-072",
"231010996856685e-073",
"9324754620109615e+212",
"78459735791271921e+049",
"272104041512242479e+200",
"6802601037806061975e+198",
"20505426358836677347e-221",
"836168422905420598437e-234",
"4891559871276714924261e+222",
// Table 2: Stress Inputs for Conversion to 53-bit Binary, > 1/2 ULP
"9e-265",
"85e-037",
"623e+100",
"3571e+263",
"81661e+153",
"920657e-023",
"4603285e-024",
"87575437e-309",
"245540327e+122",
"6138508175e+120",
"83356057653e+193",
"619534293513e+124",
"2335141086879e+218",
"36167929443327e-159",
"609610927149051e-255",
"3743626360493413e-165",
"94080055902682397e-242",
"899810892172646163e+283",
"7120190517612959703e+120",
"25188282901709339043e-252",
"308984926168550152811e-052",
"6372891218502368041059e+064",
// Table 14: Stress Inputs for Conversion to 24-bit Binary, <1/2 ULP
"5e-20",
"67e+14",
"985e+15",
"7693e-42",
"55895e-16",
"996622e-44",
"7038531e-32",
"60419369e-46",
"702990899e-20",
"6930161142e-48",
"25933168707e+13",
"596428896559e+20",
// Table 15: Stress Inputs for Conversion to 24-bit Binary, >1/2 ULP
"3e-23",
"57e+18",
"789e-35",
"2539e-18",
"76173e+28",
"887745e-11",
"5382571e-37",
"82381273e-35",
"750486563e-38",
"3752432815e-39",
"75224575729e-45",
"459926601011e+15",
// Constants plundered from strconv/atof_test.go.
"0",
"1",
"+1",
"1e23",
"1E23",
"100000000000000000000000",
"1e-100",
"123456700",
"99999999999999974834176",
"100000000000000000000001",
"100000000000000008388608",
"100000000000000016777215",
"100000000000000016777216",
"-1",
"-0.1",
"-0", // NB: exception made for this input
"1e-20",
"625e-3",
// largest float64
"1.7976931348623157e308",
"-1.7976931348623157e308",
// next float64 - too large
"1.7976931348623159e308",
"-1.7976931348623159e308",
// the border is ...158079
// borderline - okay
"1.7976931348623158e308",
"-1.7976931348623158e308",
// borderline - too large
"1.797693134862315808e308",
"-1.797693134862315808e308",
// a little too large
"1e308",
"2e308",
"1e309",
// way too large
"1e310",
"-1e310",
"1e400",
"-1e400",
"long:1e400000",
"long:-1e400000",
// denormalized
"1e-305",
"1e-306",
"1e-307",
"1e-308",
"1e-309",
"1e-310",
"1e-322",
// smallest denormal
"5e-324",
"4e-324",
"3e-324",
// too small
"2e-324",
// way too small
"1e-350",
"long:1e-400000",
// way too small, negative
"-1e-350",
"long:-1e-400000",
// try to overflow exponent
// [Disabled: too slow and memory-hungry with rationals.]
// "1e-4294967296",
// "1e+4294967296",
// "1e-18446744073709551616",
// "1e+18446744073709551616",
// http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
"2.2250738585072012e-308",
// http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
"2.2250738585072011e-308",
// A very large number (initially wrongly parsed by the fast algorithm).
"4.630813248087435e+307",
// A different kind of very large number.
"22.222222222222222",
"long:2." + strings.Repeat("2", 4000) + "e+1",
// Exactly halfway between 1 and math.Nextafter(1, 2).
// Round to even (down).
"1.00000000000000011102230246251565404236316680908203125",
// Slightly lower; still round down.
"1.00000000000000011102230246251565404236316680908203124",
// Slightly higher; round up.
"1.00000000000000011102230246251565404236316680908203126",
// Slightly higher, but you have to read all the way to the end.
"long:1.00000000000000011102230246251565404236316680908203125" + strings.Repeat("0", 10000) + "1",
// Smallest denormal, 2^(-1022-52)
"4.940656458412465441765687928682213723651e-324",
// Half of smallest denormal, 2^(-1022-53)
"2.470328229206232720882843964341106861825e-324",
// A little more than the exact half of smallest denormal
// 2^-1075 + 2^-1100. (Rounds to 1p-1074.)
"2.470328302827751011111470718709768633275e-324",
// The exact halfway between smallest normal and largest denormal:
// 2^-1022 - 2^-1075. (Rounds to 2^-1022.)
"2.225073858507201136057409796709131975935e-308",
"1152921504606846975", // 1<<60 - 1
"-1152921504606846975", // -(1<<60 - 1)
"1152921504606846977", // 1<<60 + 1
"-1152921504606846977", // -(1<<60 + 1)
"1/3",
}
// isFinite reports whether f represents a finite rational value.
// It is equivalent to !math.IsNan(f) && !math.IsInf(f, 0).
func isFinite(f float64) bool {
return math.Abs(f) <= math.MaxFloat64
}
func TestFloat32SpecialCases(t *testing.T) {
for _, input := range float64inputs {
if strings.HasPrefix(input, "long:") {
if testing.Short() {
continue
}
input = input[len("long:"):]
}
r, ok := new(Rat).SetString(input)
if !ok {
t.Errorf("Rat.SetString(%q) failed", input)
continue
}
f, exact := r.Float32()
// 1. Check string -> Rat -> float32 conversions are
// consistent with strconv.ParseFloat.
// Skip this check if the input uses "a/b" rational syntax.
if !strings.Contains(input, "/") {
e64, _ := strconv.ParseFloat(input, 32)
e := float32(e64)
// Careful: negative Rats too small for
// float64 become -0, but Rat obviously cannot
// preserve the sign from SetString("-0").
switch {
case math.Float32bits(e) == math.Float32bits(f):
// Ok: bitwise equal.
case f == 0 && r.Num().BitLen() == 0:
// Ok: Rat(0) is equivalent to both +/- float64(0).
default:
t.Errorf("strconv.ParseFloat(%q) = %g (%b), want %g (%b); delta = %g", input, e, e, f, f, f-e)
}
}
if !isFinite(float64(f)) {
continue
}
// 2. Check f is best approximation to r.
if !checkIsBestApprox32(t, f, r) {
// Append context information.
t.Errorf("(input was %q)", input)
}
// 3. Check f->R->f roundtrip is non-lossy.
checkNonLossyRoundtrip32(t, f)
// 4. Check exactness using slow algorithm.
if wasExact := new(Rat).SetFloat64(float64(f)).Cmp(r) == 0; wasExact != exact {
t.Errorf("Rat.SetString(%q).Float32().exact = %t, want %t", input, exact, wasExact)
}
}
}
func TestFloat64SpecialCases(t *testing.T) {
for _, input := range float64inputs {
if strings.HasPrefix(input, "long:") {
if testing.Short() {
continue
}
input = input[len("long:"):]
}
r, ok := new(Rat).SetString(input)
if !ok {
t.Errorf("Rat.SetString(%q) failed", input)
continue
}
f, exact := r.Float64()
// 1. Check string -> Rat -> float64 conversions are
// consistent with strconv.ParseFloat.
// Skip this check if the input uses "a/b" rational syntax.
if !strings.Contains(input, "/") {
e, _ := strconv.ParseFloat(input, 64)
// Careful: negative Rats too small for
// float64 become -0, but Rat obviously cannot
// preserve the sign from SetString("-0").
switch {
case math.Float64bits(e) == math.Float64bits(f):
// Ok: bitwise equal.
case f == 0 && r.Num().BitLen() == 0:
// Ok: Rat(0) is equivalent to both +/- float64(0).
default:
t.Errorf("strconv.ParseFloat(%q) = %g (%b), want %g (%b); delta = %g", input, e, e, f, f, f-e)
}
}
if !isFinite(f) {
continue
}
// 2. Check f is best approximation to r.
if !checkIsBestApprox64(t, f, r) {
// Append context information.
t.Errorf("(input was %q)", input)
}
// 3. Check f->R->f roundtrip is non-lossy.
checkNonLossyRoundtrip64(t, f)
// 4. Check exactness using slow algorithm.
if wasExact := new(Rat).SetFloat64(f).Cmp(r) == 0; wasExact != exact {
t.Errorf("Rat.SetString(%q).Float64().exact = %t, want %t", input, exact, wasExact)
}
}
}

73
src/cmd/compile/internal/big/ratmarsh.go
View file

@ -1,73 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements encoding/decoding of Rats.
package big
import (
"encoding/binary"
"errors"
"fmt"
)
// Gob codec version. Permits backward-compatible changes to the encoding.
const ratGobVersion byte = 1
// GobEncode implements the gob.GobEncoder interface.
func (x *Rat) GobEncode() ([]byte, error) {
if x == nil {
return nil, nil
}
buf := make([]byte, 1+4+(len(x.a.abs)+len(x.b.abs))*_S) // extra bytes for version and sign bit (1), and numerator length (4)
i := x.b.abs.bytes(buf)
j := x.a.abs.bytes(buf[:i])
n := i - j
if int(uint32(n)) != n {
// this should never happen
return nil, errors.New("Rat.GobEncode: numerator too large")
}
binary.BigEndian.PutUint32(buf[j-4:j], uint32(n))
j -= 1 + 4
b := ratGobVersion << 1 // make space for sign bit
if x.a.neg {
b |= 1
}
buf[j] = b
return buf[j:], nil
}
// GobDecode implements the gob.GobDecoder interface.
func (z *Rat) GobDecode(buf []byte) error {
if len(buf) == 0 {
// Other side sent a nil or default value.
*z = Rat{}
return nil
}
b := buf[0]
if b>>1 != ratGobVersion {
return fmt.Errorf("Rat.GobDecode: encoding version %d not supported", b>>1)
}
const j = 1 + 4
i := j + binary.BigEndian.Uint32(buf[j-4:j])
z.a.neg = b&1 != 0
z.a.abs = z.a.abs.setBytes(buf[j:i])
z.b.abs = z.b.abs.setBytes(buf[i:])
return nil
}
// MarshalText implements the encoding.TextMarshaler interface.
func (x *Rat) MarshalText() (text []byte, err error) {
// TODO(gri): get rid of the []byte/string conversion
return []byte(x.RatString()), nil
}
// UnmarshalText implements the encoding.TextUnmarshaler interface.
func (z *Rat) UnmarshalText(text []byte) error {
// TODO(gri): get rid of the []byte/string conversion
if _, ok := z.SetString(string(text)); !ok {
return fmt.Errorf("math/big: cannot unmarshal %q into a *big.Rat", text)
}
return nil
}

125
src/cmd/compile/internal/big/ratmarsh_test.go
View file

@ -1,125 +0,0 @@
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package big
import (
"bytes"
"encoding/gob"
"encoding/json"
"encoding/xml"
"testing"
)
func TestRatGobEncoding(t *testing.T) {
var medium bytes.Buffer
enc := gob.NewEncoder(&medium)
dec := gob.NewDecoder(&medium)
for _, test := range encodingTests {
medium.Reset() // empty buffer for each test case (in case of failures)
var tx Rat
tx.SetString(test + ".14159265")
if err := enc.Encode(&tx); err != nil {
t.Errorf("encoding of %s failed: %s", &tx, err)
continue
}
var rx Rat
if err := dec.Decode(&rx); err != nil {
t.Errorf("decoding of %s failed: %s", &tx, err)
continue
}
if rx.Cmp(&tx) != 0 {
t.Errorf("transmission of %s failed: got %s want %s", &tx, &rx, &tx)
}
}
}
// Sending a nil Rat pointer (inside a slice) on a round trip through gob should yield a zero.
// TODO: top-level nils.
func TestGobEncodingNilRatInSlice(t *testing.T) {
buf := new(bytes.Buffer)
enc := gob.NewEncoder(buf)
dec := gob.NewDecoder(buf)
var in = make([]*Rat, 1)
err := enc.Encode(&in)
if err != nil {
t.Errorf("gob encode failed: %q", err)
}
var out []*Rat
err = dec.Decode(&out)
if err != nil {
t.Fatalf("gob decode failed: %q", err)
}
if len(out) != 1 {
t.Fatalf("wrong len; want 1 got %d", len(out))
}
var zero Rat
if out[0].Cmp(&zero) != 0 {
t.Fatalf("transmission of (*Int)(nil) failed: got %s want 0", out)
}
}
var ratNums = []string{
"-141592653589793238462643383279502884197169399375105820974944592307816406286",
"-1415926535897932384626433832795028841971",
"-141592653589793",
"-1",
"0",
"1",
"141592653589793",
"1415926535897932384626433832795028841971",
"141592653589793238462643383279502884197169399375105820974944592307816406286",
}
var ratDenoms = []string{
"1",
"718281828459045",
"7182818284590452353602874713526624977572",
"718281828459045235360287471352662497757247093699959574966967627724076630353",
}
func TestRatJSONEncoding(t *testing.T) {
for _, num := range ratNums {
for _, denom := range ratDenoms {
var tx Rat
tx.SetString(num + "/" + denom)
b, err := json.Marshal(&tx)
if err != nil {
t.Errorf("marshaling of %s failed: %s", &tx, err)
continue
}
var rx Rat
if err := json.Unmarshal(b, &rx); err != nil {
t.Errorf("unmarshaling of %s failed: %s", &tx, err)
continue
}
if rx.Cmp(&tx) != 0 {
t.Errorf("JSON encoding of %s failed: got %s want %s", &tx, &rx, &tx)
}
}
}
}
func TestRatXMLEncoding(t *testing.T) {
for _, num := range ratNums {
for _, denom := range ratDenoms {
var tx Rat
tx.SetString(num + "/" + denom)
b, err := xml.Marshal(&tx)
if err != nil {
t.Errorf("marshaling of %s failed: %s", &tx, err)
continue
}
var rx Rat
if err := xml.Unmarshal(b, &rx); err != nil {
t.Errorf("unmarshaling of %s failed: %s", &tx, err)
continue
}
if rx.Cmp(&tx) != 0 {
t.Errorf("XML encoding of %s failed: got %s want %s", &tx, &rx, &tx)
}
}
}
}

16
src/cmd/compile/internal/big/roundingmode_string.go
View file

@ -1,16 +0,0 @@
// generated by stringer -type=RoundingMode; DO NOT EDIT
package big
import "fmt"
const _RoundingMode_name = "ToNearestEvenToNearestAwayToZeroAwayFromZeroToNegativeInfToPositiveInf"
var _RoundingMode_index = [...]uint8{0, 13, 26, 32, 44, 57, 70}
func (i RoundingMode) String() string {
if i+1 >= RoundingMode(len(_RoundingMode_index)) {
return fmt.Sprintf("RoundingMode(%d)", i)
}
return _RoundingMode_name[_RoundingMode_index[i]:_RoundingMode_index[i+1]]
}

31
src/cmd/compile/internal/big/vendor.bash
View file

@ -1,31 +0,0 @@
#!/usr/bin/env bash
# Copyright 2015 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.
# Run this script to obtain an up-to-date vendored version of math/big.
BIGDIR=../../../../math/big
# Start from scratch.
rm *.go
# We don't want any assembly files.
cp $BIGDIR/*.go .
# Use pure Go arith ops w/o build tag.
sed 's|^// \+build math_big_pure_go$||' arith_decl_pure.go > arith_decl.go
rm arith_decl_pure.go
# Import vendored math/big in external tests (e.g., floatexample_test.go).
for f in *_test.go; do
sed 's|"math/big"|"cmd/compile/internal/big"|' $f > foo.go
mv foo.go $f
done
# gofmt to clean up after sed
gofmt -w .
# Test that it works
go test -short

2
src/cmd/compile/internal/gc/bexport.go
View file

@ -132,7 +132,7 @@ package gc
import ( import (
"bufio" "bufio"
"bytes" "bytes"
"cmd/compile/internal/big" "math/big"
"encoding/binary" "encoding/binary"
"fmt" "fmt"
"sort" "sort"

2
src/cmd/compile/internal/gc/bimport.go
View file

@ -10,7 +10,7 @@ package gc
import ( import (
"bufio" "bufio"
"cmd/compile/internal/big" "math/big"
"encoding/binary" "encoding/binary"
"fmt" "fmt"
"strconv" "strconv"

2
src/cmd/compile/internal/gc/mpfloat.go
View file

@ -5,9 +5,9 @@
package gc package gc
import ( import (
"cmd/compile/internal/big"
"fmt" "fmt"
"math" "math"
"math/big"
) )
// implements float arithmetic // implements float arithmetic

2
src/cmd/compile/internal/gc/mpint.go
View file

@ -5,8 +5,8 @@
package gc package gc
import ( import (
"cmd/compile/internal/big"
"fmt" "fmt"
"math/big"
) )
// implements integer arithmetic // implements integer arithmetic

2
src/cmd/compile/internal/gc/swt_test.go
View file

@ -5,7 +5,7 @@
package gc package gc
import ( import (
"cmd/compile/internal/big" "math/big"
"testing" "testing"
) )

118
src/cmd/dist/buildtool.go vendored
View file

@ -18,49 +18,60 @@ import (
// bootstrapDirs is a list of directories holding code that must be // bootstrapDirs is a list of directories holding code that must be
// compiled with a Go 1.4 toolchain to produce the bootstrapTargets. // compiled with a Go 1.4 toolchain to produce the bootstrapTargets.
// All directories in this list are relative to and must be below $GOROOT/src/cmd. // All directories in this list are relative to and must be below $GOROOT/src.
// The list is assumed to have two kinds of entries: names without slashes, //
// which are commands, and entries beginning with internal/, which are // The list has have two kinds of entries: names beginning with cmd/ with
// packages supporting the commands. // no other slashes, which are commands, and other paths, which are packages
// supporting the commands. Packages in the standard library can be listed
// if a newer copy needs to be substituted for the Go 1.4 copy when used
// by the command packages.
// These will be imported during bootstrap as bootstrap/name, like bootstrap/math/big.
var bootstrapDirs = []string{ var bootstrapDirs = []string{
"asm", "cmd/asm",
"asm/internal/arch", "cmd/asm/internal/arch",
"asm/internal/asm", "cmd/asm/internal/asm",
"asm/internal/flags", "cmd/asm/internal/flags",
"asm/internal/lex", "cmd/asm/internal/lex",
"compile", "cmd/compile",
"compile/internal/amd64", "cmd/compile/internal/amd64",
"compile/internal/arm", "cmd/compile/internal/arm",
"compile/internal/arm64", "cmd/compile/internal/arm64",
"compile/internal/big", "cmd/compile/internal/gc",
"compile/internal/gc", "cmd/compile/internal/mips64",
"compile/internal/mips64", "cmd/compile/internal/ppc64",
"compile/internal/ppc64", "cmd/compile/internal/s390x",
"compile/internal/s390x", "cmd/compile/internal/ssa",
"compile/internal/ssa", "cmd/compile/internal/syntax",
"compile/internal/syntax", "cmd/compile/internal/x86",
"compile/internal/x86", "cmd/internal/bio",
"internal/bio", "cmd/internal/gcprog",
"internal/gcprog", "cmd/internal/dwarf",
"internal/dwarf", "cmd/internal/obj",
"internal/obj", "cmd/internal/obj/arm",
"internal/obj/arm", "cmd/internal/obj/arm64",
"internal/obj/arm64", "cmd/internal/obj/mips",
"internal/obj/mips", "cmd/internal/obj/ppc64",
"internal/obj/ppc64", "cmd/internal/obj/s390x",
"internal/obj/s390x", "cmd/internal/obj/x86",
"internal/obj/x86", "cmd/internal/sys",
"internal/sys", "cmd/link",
"link", "cmd/link/internal/amd64",
"link/internal/amd64", "cmd/link/internal/arm",
"link/internal/arm", "cmd/link/internal/arm64",
"link/internal/arm64", "cmd/link/internal/ld",
"link/internal/pe", "cmd/link/internal/mips64",
"link/internal/ld", "cmd/link/internal/pe",
"link/internal/mips64", "cmd/link/internal/ppc64",
"link/internal/ppc64", "cmd/link/internal/s390x",
"link/internal/s390x", "cmd/link/internal/x86",
"link/internal/x86", "math/big",
}
// File suffixes that use build tags introduced since Go 1.4.
// These must not be copied into the bootstrap build directory.
var ignoreSuffixes = []string{
"_arm64.s",
"_arm64.go",
} }
func bootstrapBuildTools() { func bootstrapBuildTools() {
@ -84,10 +95,16 @@ func bootstrapBuildTools() {
// Copy source code into $GOROOT/pkg/bootstrap and rewrite import paths. // Copy source code into $GOROOT/pkg/bootstrap and rewrite import paths.
for _, dir := range bootstrapDirs { for _, dir := range bootstrapDirs {
src := pathf("%s/src/cmd/%s", goroot, dir) src := pathf("%s/src/%s", goroot, dir)
dst := pathf("%s/%s", base, dir) dst := pathf("%s/%s", base, dir)
xmkdirall(dst) xmkdirall(dst)
Dir:
for _, name := range xreaddirfiles(src) { for _, name := range xreaddirfiles(src) {
for _, suf := range ignoreSuffixes {
if strings.HasSuffix(name, suf) {
continue Dir
}
}
srcFile := pathf("%s/%s", src, name) srcFile := pathf("%s/%s", src, name)
text := readfile(srcFile) text := readfile(srcFile)
text = bootstrapFixImports(text, srcFile) text = bootstrapFixImports(text, srcFile)
@ -122,10 +139,14 @@ func bootstrapBuildTools() {
// Run Go 1.4 to build binaries. Use -gcflags=-l to disable inlining to // Run Go 1.4 to build binaries. Use -gcflags=-l to disable inlining to
// workaround bugs in Go 1.4's compiler. See discussion thread: // workaround bugs in Go 1.4's compiler. See discussion thread:
// https://groups.google.com/d/msg/golang-dev/Ss7mCKsvk8w/Gsq7VYI0AwAJ // https://groups.google.com/d/msg/golang-dev/Ss7mCKsvk8w/Gsq7VYI0AwAJ
run(workspace, ShowOutput|CheckExit, pathf("%s/bin/go", goroot_bootstrap), "install", "-gcflags=-l", "-v", "bootstrap/...") run(workspace, ShowOutput|CheckExit, pathf("%s/bin/go", goroot_bootstrap), "install", "-gcflags=-l", "-v", "bootstrap/cmd/...")
// Copy binaries into tool binary directory. // Copy binaries into tool binary directory.
for _, name := range bootstrapDirs { for _, name := range bootstrapDirs {
if !strings.HasPrefix(name, "cmd/") {
continue
}
name = name[len("cmd/"):]
if !strings.Contains(name, "/") { if !strings.Contains(name, "/") {
copyfile(pathf("%s/%s%s", tooldir, name, exe), pathf("%s/bin/%s%s", workspace, name, exe), writeExec) copyfile(pathf("%s/%s%s", tooldir, name, exe), pathf("%s/bin/%s%s", workspace, name, exe), writeExec)
} }
@ -148,7 +169,14 @@ func bootstrapFixImports(text, srcFile string) string {
} }
if strings.HasPrefix(line, `import "`) || strings.HasPrefix(line, `import . "`) || if strings.HasPrefix(line, `import "`) || strings.HasPrefix(line, `import . "`) ||
inBlock && (strings.HasPrefix(line, "\t\"") || strings.HasPrefix(line, "\t. \"")) { inBlock && (strings.HasPrefix(line, "\t\"") || strings.HasPrefix(line, "\t. \"")) {
lines[i] = strings.Replace(line, `"cmd/`, `"bootstrap/`, -1) line = strings.Replace(line, `"cmd/`, `"bootstrap/cmd/`, -1)
for _, dir := range bootstrapDirs {
if strings.HasPrefix(dir, "cmd/") {
continue
}
line = strings.Replace(line, `"`+dir+`"`, `"bootstrap/`+dir+`"`, -1)
}
lines[i] = line
} }
} }