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33 lines
675 B
Go
33 lines
675 B
Go
//go:build !amd64 || appengine || !gc || noasm
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// +build !amd64 appengine !gc noasm
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// Copyright 2019+ Klaus Post. All rights reserved.
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// License information can be found in the LICENSE file.
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package zstd
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import (
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"encoding/binary"
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"math/bits"
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)
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// matchLen returns the maximum common prefix length of a and b.
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// a must be the shortest of the two.
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func matchLen(a, b []byte) (n int) {
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for ; len(a) >= 8 && len(b) >= 8; a, b = a[8:], b[8:] {
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diff := binary.LittleEndian.Uint64(a) ^ binary.LittleEndian.Uint64(b)
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if diff != 0 {
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return n + bits.TrailingZeros64(diff)>>3
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}
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n += 8
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}
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for i := range a {
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if a[i] != b[i] {
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break
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}
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n++
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}
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return n
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}
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