crc.go

Documentation: go.etcd.io/etcd/pkg/v3/crc

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package crc provides utility function for cyclic redundancy check
     6  // algorithms.
     7  package crc
     8  
     9  import (
    10  	"hash"
    11  	"hash/crc32"
    12  )
    13  
    14  // The size of a CRC-32 checksum in bytes.
    15  const Size = 4
    16  
    17  type digest struct {
    18  	crc uint32
    19  	tab *crc32.Table
    20  }
    21  
    22  // New creates a new hash.Hash32 computing the CRC-32 checksum
    23  // using the polynomial represented by the Table.
    24  // Modified by xiangli to take a prevcrc.
    25  func New(prev uint32, tab *crc32.Table) hash.Hash32 { return &digest{prev, tab} }
    26  
    27  func (d *digest) Size() int { return Size }
    28  
    29  func (d *digest) BlockSize() int { return 1 }
    30  
    31  func (d *digest) Reset() { d.crc = 0 }
    32  
    33  func (d *digest) Write(p []byte) (n int, err error) {
    34  	d.crc = crc32.Update(d.crc, d.tab, p)
    35  	return len(p), nil
    36  }
    37  
    38  func (d *digest) Sum32() uint32 { return d.crc }
    39  
    40  func (d *digest) Sum(in []byte) []byte {
    41  	s := d.Sum32()
    42  	return append(in, byte(s>>24), byte(s>>16), byte(s>>8), byte(s))
    43  }
    44
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