github.com/emmansun/gmsm@v0.29.1/internal/subtle/xor_arm64.s (about)

     1  // Copyright 2020 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  #include "textflag.h"
     8  
     9  // func xorBytes(dst, a, b *byte, n int)
    10  TEXT ·xorBytes(SB), NOSPLIT|NOFRAME, $0
    11  	MOVD	dst+0(FP), R0
    12  	MOVD	a+8(FP), R1
    13  	MOVD	b+16(FP), R2
    14  	MOVD	n+24(FP), R3
    15  	CMP	$64, R3
    16  	BLT	tail
    17  loop_64:
    18  	VLD1.P	64(R1), [V0.B16, V1.B16, V2.B16, V3.B16]
    19  	VLD1.P	64(R2), [V4.B16, V5.B16, V6.B16, V7.B16]
    20  	VEOR	V0.B16, V4.B16, V4.B16
    21  	VEOR	V1.B16, V5.B16, V5.B16
    22  	VEOR	V2.B16, V6.B16, V6.B16
    23  	VEOR	V3.B16, V7.B16, V7.B16
    24  	VST1.P	[V4.B16, V5.B16, V6.B16, V7.B16], 64(R0)
    25  	SUBS	$64, R3
    26  	CMP	$64, R3
    27  	BGE	loop_64
    28  tail:
    29  	// quick end
    30  	CBZ	R3, end
    31  	TBZ	$5, R3, less_than32
    32  	VLD1.P	32(R1), [V0.B16, V1.B16]
    33  	VLD1.P	32(R2), [V2.B16, V3.B16]
    34  	VEOR	V0.B16, V2.B16, V2.B16
    35  	VEOR	V1.B16, V3.B16, V3.B16
    36  	VST1.P	[V2.B16, V3.B16], 32(R0)
    37  less_than32:
    38  	TBZ	$4, R3, less_than16
    39  	LDP.P	16(R1), (R11, R12)
    40  	LDP.P	16(R2), (R13, R14)
    41  	EOR	R11, R13, R13
    42  	EOR	R12, R14, R14
    43  	STP.P	(R13, R14), 16(R0)
    44  less_than16:
    45  	TBZ	$3, R3, less_than8
    46  	MOVD.P	8(R1), R11
    47  	MOVD.P	8(R2), R12
    48  	EOR	R11, R12, R12
    49  	MOVD.P	R12, 8(R0)
    50  less_than8:
    51  	TBZ	$2, R3, less_than4
    52  	MOVWU.P	4(R1), R13
    53  	MOVWU.P	4(R2), R14
    54  	EORW	R13, R14, R14
    55  	MOVWU.P	R14, 4(R0)
    56  less_than4:
    57  	TBZ	$1, R3, less_than2
    58  	MOVHU.P	2(R1), R15
    59  	MOVHU.P	2(R2), R16
    60  	EORW	R15, R16, R16
    61  	MOVHU.P	R16, 2(R0)
    62  less_than2:
    63  	TBZ	$0, R3, end
    64  	MOVBU	(R1), R17
    65  	MOVBU	(R2), R19
    66  	EORW	R17, R19, R19
    67  	MOVBU	R19, (R0)
    68  end:
    69  	RET