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// Inferno's libkern/memmove-386.s
// http://code.google.com/p/inferno-os/source/browse/libkern/memmove-386.s
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
// Portions Copyright 2009 The Go Authors. All rights reserved.
//
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// furnished to do so, subject to the following conditions:
//
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//
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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TEXT runtime·memmove(SB), 7, $0
MOVL to+0(FP), DI
MOVL fr+4(FP), SI
MOVL n+8(FP), BX
CMPL BX, $0
JLT fault
/*
* check and set for backwards
*/
CMPL SI, DI
JLS back
/*
* forward copy loop
*/
forward:
MOVL BX, CX
SHRL $2, CX
ANDL $3, BX
REP; MOVSL
MOVL BX, CX
REP; MOVSB
MOVL to+0(FP),AX
RET
/*
* check overlap
*/
back:
MOVL SI, CX
ADDL BX, CX
CMPL CX, DI
JLS forward
/*
* whole thing backwards has
* adjusted addresses
*/
ADDL BX, DI
ADDL BX, SI
STD
/*
* copy
*/
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
MOVL to+0(FP),AX
RET
/*
* if called with negative count,
* treat as error rather than
* rotating all of memory
*/
fault:
MOVL $0,SI
MOVL 0(SI), AX
RET