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// Copyright 2017 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 catmsg
// This file implements varint encoding analogous to the one in encoding/binary.
// We need a string version of this function, so we add that here and then add
// the rest for consistency.
import "errors"
var (
errIllegalVarint = errors.New("catmsg: illegal varint")
errVarintTooLarge = errors.New("catmsg: varint too large for uint64")
)
const maxVarintBytes = 10 // maximum length of a varint
// encodeUint encodes x as a variable-sized integer into buf and returns the
// number of bytes written. buf must be at least maxVarintBytes long
func encodeUint(buf []byte, x uint64) (n int) {
for ; x > 127; n++ {
buf[n] = 0x80 | uint8(x&0x7F)
x >>= 7
}
buf[n] = uint8(x)
n++
return n
}
func decodeUintString(s string) (x uint64, size int, err error) {
i := 0
for shift := uint(0); shift < 64; shift += 7 {
if i >= len(s) {
return 0, i, errIllegalVarint
}
b := uint64(s[i])
i++
x |= (b & 0x7F) << shift
if b&0x80 == 0 {
return x, i, nil
}
}
return 0, i, errVarintTooLarge
}
func decodeUint(b []byte) (x uint64, size int, err error) {
i := 0
for shift := uint(0); shift < 64; shift += 7 {
if i >= len(b) {
return 0, i, errIllegalVarint
}
c := uint64(b[i])
i++
x |= (c & 0x7F) << shift
if c&0x80 == 0 {
return x, i, nil
}
}
return 0, i, errVarintTooLarge
}
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