github.com/hbdrawn/golang@v0.0.0-20141214014649-6b835209aba2/src/hash/crc32/crc32_amd64x.go (about)

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build amd64 amd64p32
     6  
     7  package crc32
     8  
     9  // This file contains the code to call the SSE 4.2 version of the Castagnoli
    10  // CRC.
    11  
    12  // haveSSE42 is defined in crc_amd64.s and uses CPUID to test for SSE 4.2
    13  // support.
    14  func haveSSE42() bool
    15  
    16  // castagnoliSSE42 is defined in crc_amd64.s and uses the SSE4.2 CRC32
    17  // instruction.
    18  func castagnoliSSE42(crc uint32, p []byte) uint32
    19  
    20  var sse42 = haveSSE42()
    21  
    22  func updateCastagnoli(crc uint32, p []byte) uint32 {
    23  	if sse42 {
    24  		return castagnoliSSE42(crc, p)
    25  	}
    26  	return update(crc, castagnoliTable, p)
    27  }