forgejo-federation/vendor/github.com/syndtr/goleveldb/leveldb/util/crc32.go

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2019-02-05 22:22:51 +05:30
// 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
}