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https://github.com/taigrr/arc
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63 lines
1.6 KiB
Go
63 lines
1.6 KiB
Go
// 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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// and IEEE CRC.
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// haveSSE41/haveSSE42/haveCLMUL are defined in crc_amd64.s and use
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// CPUID to test for SSE 4.1, 4.2 and CLMUL support.
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func haveSSE41() bool
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func haveSSE42() bool
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func haveCLMUL() 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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//go:noescape
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func castagnoliSSE42(crc uint32, p []byte) uint32
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// ieeeCLMUL is defined in crc_amd64.s and uses the PCLMULQDQ
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// instruction as well as SSE 4.1.
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//go:noescape
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func ieeeCLMUL(crc uint32, p []byte) uint32
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var sse42 = haveSSE42()
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var useFastIEEE = haveCLMUL() && haveSSE41()
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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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// only use slicing-by-8 when input is >= 16 Bytes
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if len(p) >= 16 {
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return updateSlicingBy8(crc, castagnoliTable8, 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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if useFastIEEE && len(p) >= 64 {
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left := len(p) & 15
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do := len(p) - left
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crc = ^ieeeCLMUL(^crc, p[:do])
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if left > 0 {
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crc = update(crc, IEEETable, p[do:])
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}
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return crc
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}
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// only use slicing-by-8 when input is >= 16 Bytes
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if len(p) >= 16 {
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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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