45 lines
1.3 KiB
Go
45 lines
1.3 KiB
Go
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package oss
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import (
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"hash"
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"hash/crc64"
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)
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// digest represents the partial evaluation of a checksum.
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type digest struct {
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crc uint64
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tab *crc64.Table
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}
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// NewCRC creates a new hash.Hash64 computing the CRC-64 checksum
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// using the polynomial represented by the Table.
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func NewCRC(tab *crc64.Table, init uint64) hash.Hash64 { return &digest{init, tab} }
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// Size returns the number of bytes Sum will return.
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func (d *digest) Size() int { return crc64.Size }
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// BlockSize returns the hash's underlying block size.
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// The Write method must be able to accept any amount
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// of data, but it may operate more efficiently if all writes
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// are a multiple of the block size.
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func (d *digest) BlockSize() int { return 1 }
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// Reset resets the Hash to its initial state.
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func (d *digest) Reset() { d.crc = 0 }
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// Write (via the embedded io.Writer interface) adds more data to the running hash.
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// It never returns an error.
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func (d *digest) Write(p []byte) (n int, err error) {
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d.crc = crc64.Update(d.crc, d.tab, p)
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return len(p), nil
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}
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// Sum64 returns crc64 value.
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func (d *digest) Sum64() uint64 { return d.crc }
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// Sum returns hash value.
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func (d *digest) Sum(in []byte) []byte {
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s := d.Sum64()
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return append(in, byte(s>>56), byte(s>>48), byte(s>>40), byte(s>>32), byte(s>>24), byte(s>>16), byte(s>>8), byte(s))
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}
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