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minio/pkg/utils/checksum/crc32c/crc32c_linux.go

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2.1 KiB

// Copyright 2009 The 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.
// Golang project:
// https://github.com/golang/go/blob/master/LICENSE
// Using this part of Minio codebase under the license
// Apache License Version 2.0 with modifications
// Package crc32 implements the 32-bit cyclic redundancy check, or CRC-32,
// checksum. See http://en.wikipedia.org/wiki/Cyclic_redundancy_check for
// information.
package crc32c
import (
"hash"
"io"
)
// The size of a CRC-32 checksum in bytes.
const Size = 4
// digest represents the partial evaluation of a checksum.
type digest struct {
crc uint32
}
// New creates a new hash.Hash32 computing the CRC-32 checksum
// using the polynomial represented by the Table.
func New() hash.Hash32 {
return &digest{crc: 0}
}
// Return size of crc
func (d *digest) Size() int { return Size }
// Stub
func (d *digest) BlockSize() int { return 1 }
// Get crc in bytes
func (d *digest) Sum(in []byte) []byte {
s := d.crc
return append(in, byte(s>>24), byte(s>>16), byte(s>>8), byte(s))
}
// Sum32 - return current crc in digest object
func (d *digest) Sum32() uint32 { return d.crc }
// Reset default crc
func (d *digest) Reset() { d.crc = 0 }
// Update returns the result of adding the bytes in p to the crc.
func (d *digest) update(crc uint32, p []byte) uint32 {
return updateCastanagoliPCL(crc, p)
}
// Write data
func (d *digest) Write(p []byte) (n int, err error) {
d.crc = d.update(d.crc, p)
return len(p), nil
}
/// Convenience functions
// Sum32 - single caller crc helper
func Sum32(data []byte) uint32 {
crc32 := New()
crc32.Reset()
crc32.Write(data)
return crc32.Sum32()
}
// Sum - low memory footprint io.Reader based crc helper
func Sum(reader io.Reader) (uint32, error) {
h := New()
var err error
for err == nil {
length := 0
byteBuffer := make([]byte, 1024*1024)
length, err = reader.Read(byteBuffer)
byteBuffer = byteBuffer[0:length]
h.Write(byteBuffer)
}
if err != io.EOF {
return 0, err
}
return h.Sum32(), nil
}