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// Copyright 2016 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.
// void runtime·memmove(void*, void*, uintptr)
TEXT runtime·memmove(SB),NOSPLIT,$-0-24
MOV to+0(FP), T0
MOV from+8(FP), T1
MOV n+16(FP), T2
ADD T1, T2, T5
// If the destination is ahead of the source, start at the end of the
// buffer and go backward.
BLTU T1, T0, b
// If less than eight bytes, do one byte at a time.
SLTU $8, T2, T3
BNE T3, ZERO, f_outcheck
// Do one byte at a time until from is eight-aligned.
JMP f_aligncheck
f_align:
MOVB (T1), T3
MOVB T3, (T0)
ADD $1, T0
ADD $1, T1
f_aligncheck:
AND $7, T1, T3
BNE T3, ZERO, f_align
// Do eight bytes at a time as long as there is room.
ADD $-7, T5, T6
JMP f_wordscheck
f_words:
MOV (T1), T3
MOV T3, (T0)
ADD $8, T0
ADD $8, T1
f_wordscheck:
SLTU T6, T1, T3
BNE T3, ZERO, f_words
// Finish off the remaining partial word.
JMP f_outcheck
f_out:
MOVB (T1), T3
MOVB T3, (T0)
ADD $1, T0
ADD $1, T1
f_outcheck:
BNE T1, T5, f_out
RET
b:
ADD T0, T2, T4
// If less than eight bytes, do one byte at a time.
SLTU $8, T2, T3
BNE T3, ZERO, b_outcheck
// Do one byte at a time until from+n is eight-aligned.
JMP b_aligncheck
b_align:
ADD $-1, T4
ADD $-1, T5
MOVB (T5), T3
MOVB T3, (T4)
b_aligncheck:
AND $7, T5, T3
BNE T3, ZERO, b_align
// Do eight bytes at a time as long as there is room.
ADD $7, T1, T6
JMP b_wordscheck
b_words:
ADD $-8, T4
ADD $-8, T5
MOV (T5), T3
MOV T3, (T4)
b_wordscheck:
SLTU T5, T6, T3
BNE T3, ZERO, b_words
// Finish off the remaining partial word.
JMP b_outcheck
b_out:
ADD $-1, T4
ADD $-1, T5
MOVB (T5), T3
MOVB T3, (T4)
b_outcheck:
BNE T5, T1, b_out
RET
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