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Source file src/crypto/sha1/sha1block_amd64.go

Documentation: crypto/sha1

  // Copyright 2016 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package sha1
  
  import "internal/cpu"
  
  //go:noescape
  func blockAVX2(dig *digest, p []byte)
  
  //go:noescape
  func blockAMD64(dig *digest, p []byte)
  
  var useAVX2 = cpu.X86.HasAVX2 && cpu.X86.HasBMI1 && cpu.X86.HasBMI2
  
  func block(dig *digest, p []byte) {
  	if useAVX2 && len(p) >= 256 {
  		// blockAVX2 calculates sha1 for 2 block per iteration
  		// it also interleaves precalculation for next block.
  		// So it may read up-to 192 bytes past end of p
  		// We may add checks inside blockAVX2, but this will
  		// just turn it into a copy of blockAMD64,
  		// so call it directly, instead.
  		safeLen := len(p) - 128
  		if safeLen%128 != 0 {
  			safeLen -= 64
  		}
  		blockAVX2(dig, p[:safeLen])
  		blockAMD64(dig, p[safeLen:])
  	} else {
  		blockAMD64(dig, p)
  	}
  }
  

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