integer encode/decode

R=rsc
DELTA=185  (175 added, 10 deleted, 0 changed)
OCL=30863
CL=30871

src/pkg/gob/decode.go

@@ -0,0 +1,40 @@
+// 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 gob
+
+import (
+	"io";
+	"os";
+)
+
+// DecodeUint reads an encoded unsigned integer from r.
+func DecodeUint(r io.Reader) (x uint64, err os.Error) {
+	var buf [1]byte;
+	for shift := uint(0);; shift += 7 {
+		n, err := r.Read(&buf);
+		if n != 1 {
+			return 0, err
+		}
+		b := uint64(buf[0]);
+		x |= b << shift;
+		if b&0x80 != 0 {
+			x &^= 0x80 << shift;
+			break
+		}
+	}
+	return x, nil;
+}
+
+// DecodeInt reads an encoded signed integer from r.
+func DecodeInt(r io.Reader) (i int64, err os.Error) {
+	x, err := DecodeUint(r);
+	if err != nil {
+		return
+	}
+	if x & 1 != 0 {
+		return ^int64(x>>1), nil
+	}
+	return int64(x >> 1), nil
+}