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