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
7package sha1
8
9import "internal/cpu"
10
11//go:noescape
12func blockAVX2(dig *digest, p []byte)
13
14//go:noescape
15func blockAMD64(dig *digest, p []byte)
16
17var useAVX2 = cpu.X86.HasAVX2 && cpu.X86.HasBMI1 && cpu.X86.HasBMI2
18
19func 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