sha1block_amd64.go

     1  // Copyright 2016 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  //go:build !purego
     6  
     7  package sha1
     8  
     9  import "internal/cpu"
    10  
    11  //go:noescape
    12  func blockAVX2(dig *digest, p []byte)
    13  
    14  //go:noescape
    15  func blockAMD64(dig *digest, p []byte)
    16  
    17  var useAVX2 = cpu.X86.HasAVX2 && cpu.X86.HasBMI1 && cpu.X86.HasBMI2
    18  
    19  func block(dig *digest, p []byte) {
    20  	if useAVX2 && len(p) >= 256 {
    21  		// blockAVX2 calculates sha1 for 2 block per iteration
    22  		// it also interleaves precalculation for next block.
    23  		// So it may read up-to 192 bytes past end of p
    24  		// We may add checks inside blockAVX2, but this will
    25  		// just turn it into a copy of blockAMD64,
    26  		// so call it directly, instead.
    27  		safeLen := len(p) - 128
    28  		if safeLen%128 != 0 {
    29  			safeLen -= 64
    30  		}
    31  		blockAVX2(dig, p[:safeLen])
    32  		blockAMD64(dig, p[safeLen:])
    33  	} else {
    34  		blockAMD64(dig, p)
    35  	}
    36  }
    37
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