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// Copyright 2022 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" // See memmove Go doc for important implementation constraints. // func memmove(to, from unsafe.Pointer, n uintptr) TEXT runtime·memmove<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-24 #ifndef GOEXPERIMENT_regabiargs MOVV to+0(FP), R4 MOVV from+8(FP), R5 MOVV n+16(FP), R6 #endif BNE R6, check RET check: SGTU R4, R5, R7 BNE R7, backward ADDV R4, R6, R9 // end pointer // if the two pointers are not of same alignments, do byte copying SUBVU R5, R4, R7 AND $7, R7 BNE R7, out // if less than 8 bytes, do byte copying SGTU $8, R6, R7 BNE R7, out // do one byte at a time until 8-aligned AND $7, R4, R8 BEQ R8, words MOVB (R5), R7 ADDV $1, R5 MOVB R7, (R4) ADDV $1, R4 JMP -6(PC) words: // do 8 bytes at a time if there is room ADDV $-7, R9, R6 // R6 is end pointer-7 PCALIGN $16 SGTU R6, R4, R8 BEQ R8, out MOVV (R5), R7 ADDV $8, R5 MOVV R7, (R4) ADDV $8, R4 JMP -6(PC) out: BEQ R4, R9, done MOVB (R5), R7 ADDV $1, R5 MOVB R7, (R4) ADDV $1, R4 JMP -5(PC) done: RET backward: ADDV R6, R5 // from-end pointer ADDV R4, R6, R9 // to-end pointer // if the two pointers are not of same alignments, do byte copying SUBVU R9, R5, R7 AND $7, R7 BNE R7, out1 // if less than 8 bytes, do byte copying SGTU $8, R6, R7 BNE R7, out1 // do one byte at a time until 8-aligned AND $7, R9, R8 BEQ R8, words1 ADDV $-1, R5 MOVB (R5), R7 ADDV $-1, R9 MOVB R7, (R9) JMP -6(PC) words1: // do 8 bytes at a time if there is room ADDV $7, R4, R6 // R6 is start pointer+7 PCALIGN $16 SGTU R9, R6, R8 BEQ R8, out1 ADDV $-8, R5 MOVV (R5), R7 ADDV $-8, R9 MOVV R7, (R9) JMP -6(PC) out1: BEQ R4, R9, done1 ADDV $-1, R5 MOVB (R5), R7 ADDV $-1, R9 MOVB R7, (R9) JMP -5(PC) done1: RET