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 (
    10  	"crypto/internal/impl"
    11  	"internal/cpu"
    12  )
    13  
    14  //go:noescape
    15  func blockAVX2(dig *digest, p []byte)
    16  
    17  //go:noescape
    18  func blockSHANI(dig *digest, p []byte)
    19  
    20  var useAVX2 = cpu.X86.HasAVX && cpu.X86.HasAVX2 && cpu.X86.HasBMI1 && cpu.X86.HasBMI2
    21  var useSHANI = cpu.X86.HasAVX && cpu.X86.HasSHA && cpu.X86.HasSSE41 && cpu.X86.HasSSSE3
    22  
    23  func init() {
    24  	impl.Register("sha1", "AVX2", &useAVX2)
    25  	impl.Register("sha1", "SHA-NI", &useSHANI)
    26  }
    27  
    28  func block(dig *digest, p []byte) {
    29  	if useSHANI {
    30  		blockSHANI(dig, p)
    31  	} else if useAVX2 && len(p) >= 256 {
    32  		// blockAVX2 calculates sha1 for 2 block per iteration and also
    33  		// interleaves precalculation for next block. So it may read up-to 192
    34  		// bytes past end of p. We could add checks inside blockAVX2, but this
    35  		// would just turn it into a copy of the old pre-AVX2 amd64 SHA1
    36  		// assembly implementation, so just call blockGeneric instead.
    37  		safeLen := len(p) - 128
    38  		if safeLen%128 != 0 {
    39  			safeLen -= 64
    40  		}
    41  		blockAVX2(dig, p[:safeLen])
    42  		blockGeneric(dig, p[safeLen:])
    43  	} else {
    44  		blockGeneric(dig, p)
    45  	}
    46  }
    47
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