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43 lines
1 KiB
Go
43 lines
1 KiB
Go
// Copyright 2009 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 crc provides utility function for cyclic redundancy check
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// algorithms.
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package crc
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import (
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"hash"
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"hash/crc32"
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)
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// The size of a CRC-32 checksum in bytes.
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const Size = 4
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type digest struct {
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crc uint32
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tab *crc32.Table
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}
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// New creates a new hash.Hash32 computing the CRC-32 checksum
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// using the polynomial represented by the Table.
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// Modified by xiangli to take a prevcrc.
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func New(prev uint32, tab *crc32.Table) hash.Hash32 { return &digest{prev, tab} }
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func (d *digest) Size() int { return Size }
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func (d *digest) BlockSize() int { return 1 }
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func (d *digest) Reset() { d.crc = 0 }
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func (d *digest) Write(p []byte) (n int, err error) {
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d.crc = crc32.Update(d.crc, d.tab, p)
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return len(p), nil
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}
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func (d *digest) Sum32() uint32 { return d.crc }
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func (d *digest) Sum(in []byte) []byte {
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s := d.Sum32()
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return append(in, byte(s>>24), byte(s>>16), byte(s>>8), byte(s))
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}
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