limited support arm64 assembly language

internal/xor/xor_arm64.go

@@ -0,0 +1,29 @@
+// Copyright 2018 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 xor
+
+// xorBytes xors the bytes in a and b. The destination should have enough
+// space, otherwise xorBytes will panic. Returns the number of bytes xor'd.
+func XorBytes(dst, a, b []byte) int {
+	n := len(a)
+	if len(b) < n {
+		n = len(b)
+	}
+	if n == 0 {
+		return 0
+	}
+	// make sure dst has enough space
+	_ = dst[n-1]
+
+	xorBytesARM64(&dst[0], &a[0], &b[0], n)
+	return n
+}
+
+func XorWords(dst, a, b []byte) {
+	XorBytes(dst, a, b)
+}
+
+//go:noescape
+func xorBytesARM64(dst, a, b *byte, n int)

internal/xor/xor_arm64.s

@@ -0,0 +1,67 @@
+// Copyright 2020 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.
+
+#include "textflag.h"
+
+// func xorBytesARM64(dst, a, b *byte, n int)
+TEXT ·xorBytesARM64(SB), NOSPLIT|NOFRAME, $0
+	MOVD	dst+0(FP), R0
+	MOVD	a+8(FP), R1
+	MOVD	b+16(FP), R2
+	MOVD	n+24(FP), R3
+	CMP	$64, R3
+	BLT	tail
+loop_64:
+	VLD1.P	64(R1), [V0.B16, V1.B16, V2.B16, V3.B16]
+	VLD1.P	64(R2), [V4.B16, V5.B16, V6.B16, V7.B16]
+	VEOR	V0.B16, V4.B16, V4.B16
+	VEOR	V1.B16, V5.B16, V5.B16
+	VEOR	V2.B16, V6.B16, V6.B16
+	VEOR	V3.B16, V7.B16, V7.B16
+	VST1.P	[V4.B16, V5.B16, V6.B16, V7.B16], 64(R0)
+	SUBS	$64, R3
+	CMP	$64, R3
+	BGE	loop_64
+tail:
+	// quick end
+	CBZ	R3, end
+	TBZ	$5, R3, less_than32
+	VLD1.P	32(R1), [V0.B16, V1.B16]
+	VLD1.P	32(R2), [V2.B16, V3.B16]
+	VEOR	V0.B16, V2.B16, V2.B16
+	VEOR	V1.B16, V3.B16, V3.B16
+	VST1.P	[V2.B16, V3.B16], 32(R0)
+less_than32:
+	TBZ	$4, R3, less_than16
+	LDP.P	16(R1), (R11, R12)
+	LDP.P	16(R2), (R13, R14)
+	EOR	R11, R13, R13
+	EOR	R12, R14, R14
+	STP.P	(R13, R14), 16(R0)
+less_than16:
+	TBZ	$3, R3, less_than8
+	MOVD.P	8(R1), R11
+	MOVD.P	8(R2), R12
+	EOR	R11, R12, R12
+	MOVD.P	R12, 8(R0)
+less_than8:
+	TBZ	$2, R3, less_than4
+	MOVWU.P	4(R1), R13
+	MOVWU.P	4(R2), R14
+	EORW	R13, R14, R14
+	MOVWU.P	R14, 4(R0)
+less_than4:
+	TBZ	$1, R3, less_than2
+	MOVHU.P	2(R1), R15
+	MOVHU.P	2(R2), R16
+	EORW	R15, R16, R16
+	MOVHU.P	R16, 2(R0)
+less_than2:
+	TBZ	$0, R3, end
+	MOVBU	(R1), R17
+	MOVBU	(R2), R19
+	EORW	R17, R19, R19
+	MOVBU	R19, (R0)
+end:
+	RET

internal/xor/xor_generic.go

@@ -1,8 +1,8 @@
 // Copyright 2013 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.
-//go:build !amd64
+//go:build !amd64 && !arm64
-// +build !amd64
+// +build !amd64,!arm64
 
 package xor