1 // Copyright 2011 The LevelDB-Go Authors. All rights reserved. 2 // 3 // Use of this source code is governed by a BSD-style license that can be 4 // found in the LICENSE file. 5 6 package util 7 8 import ( 9 "hash/crc32" 10 ) 11 12 var table = crc32.MakeTable(crc32.Castagnoli) 13 14 // CRC is a CRC-32 checksum computed using Castagnoli's polynomial. 15 type CRC uint32 16 17 // NewCRC creates a new crc based on the given bytes. 18 func NewCRC(b []byte) CRC { 19 return CRC(0).Update(b) 20 } 21 22 // Update updates the crc with the given bytes. 23 func (c CRC) Update(b []byte) CRC { 24 return CRC(crc32.Update(uint32(c), table, b)) 25 } 26 27 // Value returns a masked crc. 28 func (c CRC) Value() uint32 { 29 return uint32(c>>15|c<<17) + 0xa282ead8 30 } 31