40 lines
973 B
Go
40 lines
973 B
Go
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !appengine,!gccgo
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package crc32
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// This file contains the code to call the SSE 4.2 version of the Castagnoli
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// CRC.
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// haveSSE42 is defined in crc_amd64p32.s and uses CPUID to test for 4.2
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// support.
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func haveSSE42() bool
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// castagnoliSSE42 is defined in crc_amd64.s and uses the SSE4.2 CRC32
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// instruction.
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func castagnoliSSE42(crc uint32, p []byte) uint32
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var sse42 = haveSSE42()
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func updateCastagnoli(crc uint32, p []byte) uint32 {
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if sse42 {
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return castagnoliSSE42(crc, p)
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}
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return update(crc, castagnoliTable, p)
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}
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func updateIEEE(crc uint32, p []byte) uint32 {
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// only use slicing-by-8 when input is >= 4KB
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if len(p) >= 4096 {
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iEEETable8Once.Do(func() {
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iEEETable8 = makeTable8(IEEE)
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})
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return updateSlicingBy8(crc, iEEETable8, p)
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}
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return update(crc, IEEETable, p)
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}
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