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55 lines
1.3 KiB
55 lines
1.3 KiB
3 years ago
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// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "textflag.h"
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// func xorBytesSSE2(dst, a, b *byte, n int)
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TEXT ·xorBytesSSE2(SB), NOSPLIT, $0
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MOVQ dst+0(FP), BX
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MOVQ a+8(FP), SI
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MOVQ b+16(FP), CX
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MOVQ n+24(FP), DX
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TESTQ $15, DX // AND 15 & len, if not zero jump to not_aligned.
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JNZ not_aligned
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aligned:
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MOVQ $0, AX // position in slices
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loop16b:
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MOVOU (SI)(AX*1), X0 // XOR 16byte forwards.
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MOVOU (CX)(AX*1), X1
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PXOR X1, X0
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MOVOU X0, (BX)(AX*1)
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ADDQ $16, AX
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CMPQ DX, AX
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JNE loop16b
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RET
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loop_1b:
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SUBQ $1, DX // XOR 1byte backwards.
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MOVB (SI)(DX*1), DI
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MOVB (CX)(DX*1), AX
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XORB AX, DI
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MOVB DI, (BX)(DX*1)
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TESTQ $7, DX // AND 7 & len, if not zero jump to loop_1b.
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JNZ loop_1b
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CMPQ DX, $0 // if len is 0, ret.
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JE ret
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TESTQ $15, DX // AND 15 & len, if zero jump to aligned.
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JZ aligned
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not_aligned:
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TESTQ $7, DX // AND $7 & len, if not zero jump to loop_1b.
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JNE loop_1b
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SUBQ $8, DX // XOR 8bytes backwards.
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MOVQ (SI)(DX*1), DI
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MOVQ (CX)(DX*1), AX
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XORQ AX, DI
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MOVQ DI, (BX)(DX*1)
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CMPQ DX, $16 // if len is greater or equal 16 here, it must be aligned.
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JGE aligned
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ret:
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RET
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