forked from Shiloh/githaven
31 lines
691 B
Go
31 lines
691 B
Go
|
// Copyright 2011 The LevelDB-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 util
|
||
|
|
|
||
|
|
import (
|
||
|
|
"hash/crc32"
|
||
|
|
)
|
||
|
|
|
||
|
|
var table = crc32.MakeTable(crc32.Castagnoli)
|
||
|
|
|
||
|
|
// CRC is a CRC-32 checksum computed using Castagnoli's polynomial.
|
||
|
|
type CRC uint32
|
||
|
|
|
||
|
|
// NewCRC creates a new crc based on the given bytes.
|
||
|
|
func NewCRC(b []byte) CRC {
|
||
|
|
return CRC(0).Update(b)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Update updates the crc with the given bytes.
|
||
|
|
func (c CRC) Update(b []byte) CRC {
|
||
|
|
return CRC(crc32.Update(uint32(c), table, b))
|
||
|
|
}
|
||
|
|
|
||
|
|
// Value returns a masked crc.
|
||
|
|
func (c CRC) Value() uint32 {
|
||
|
|
return uint32(c>>15|c<<17) + 0xa282ead8
|
||
|
|
}
|