blob: 13907a90b2cb085c5d4c8adb1d1f6451b4e4e19e [file] [log] [blame]
// 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.
#include "textflag.h"
// This could use MOVSQ, but we use MOVSL so that if an object ends in
// a 4 byte pointer, we copy it as a unit instead of byte by byte.
TEXT runtimeĀ·memmove(SB), NOSPLIT, $0-12
MOVL to+0(FP), DI
MOVL from+4(FP), SI
MOVL n+8(FP), BX
CMPL SI, DI
JLS back
forward:
MOVL BX, CX
SHRL $2, CX
ANDL $3, BX
REP; MOVSL
MOVL BX, CX
REP; MOVSB
RET
back:
MOVL SI, CX
ADDL BX, CX
CMPL CX, DI
JLS forward
ADDL BX, DI
ADDL BX, SI
STD
MOVL BX, CX
SHRL $2, CX
ANDL $3, BX
SUBL $4, DI
SUBL $4, SI
REP; MOVSL
ADDL $3, DI
ADDL $3, SI
MOVL BX, CX
REP; MOVSB
CLD
// Note: we copy only 4 bytes at a time so that the tail is at most
// 3 bytes. That guarantees that we aren't copying pointers with MOVSB.
// See issue 13160.
RET