clamav/libclamav/tomsfastmath/mul/fp_mul_2d.c
Micah Snyder 375ecf678c Update vendored TomsFastMath code to 0.13.1
Update the vendored TomsFastMath (TFM) library to v0.13.1.

Resolves: https://bugzilla.clamav.net/show_bug.cgi?id=11992

I removed compatibility macro's from when libTomMath was used.
This required removing a bunch of faux-error handling because
the fast-math equivalent functions return void, and cannot fail.

The previous version used had named the header "bignum_fast.h"
instead of "tfm.h" and had customizations in that header to enable
TFM_CHECK all the time, and also TFM_NO_ASM if __GNUC__ not defined
or if the system isn't 64bit architecture. This update uses tfm.h
as-is, and has CMake define TFM_CHECK and TFM_NO_ASM as needed.

I've kept bignum.h as an interface to including tfm.h so that in
the future we can more easily add support for system-installed
TomsFastMath instead of the vendored one, taking inspiration from
Debian's patch to support system-TomsFastMath.

See: https://salsa.debian.org/clamav-team/clamav/-/blob/unstable/debian/patches/add-support-for-system-tomsfastmath.patch
2022-02-10 12:54:23 -07:00

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C

/* TomsFastMath, a fast ISO C bignum library.
*
* This project is meant to fill in where LibTomMath
* falls short. That is speed ;-)
*
* This project is public domain and free for all purposes.
*
* Tom St Denis, tomstdenis@gmail.com
*/
#include <tfm_private.h>
/* c = a * 2**d */
void fp_mul_2d(fp_int *a, int b, fp_int *c)
{
fp_digit carry, carrytmp, shift;
int x;
/* copy it */
fp_copy(a, c);
/* handle whole digits */
if (b >= DIGIT_BIT) {
fp_lshd(c, b/DIGIT_BIT);
}
b %= DIGIT_BIT;
/* shift the digits */
if (b != 0) {
carry = 0;
shift = DIGIT_BIT - b;
for (x = 0; x < c->used; x++) {
carrytmp = c->dp[x] >> shift;
c->dp[x] = (c->dp[x] << b) + carry;
carry = carrytmp;
}
/* store last carry if room */
if (carry && x < FP_SIZE) {
c->dp[c->used++] = carry;
}
}
fp_clamp(c);
}
/* $Source$ */
/* $Revision$ */
/* $Date$ */