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// Inferno's libkern/memmove-386.s
// http://code.google.com/p/inferno-os/source/browse/libkern/memmove-386.s
//
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// Portions Copyright 2009 The Go Authors. All rights reserved.
//
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//
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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
* should we look closer for overlap?
*/
CMPL SI, DI
JLS back
/*
* forward copy loop
*/
MOVL BX, CX
SHRL $2, CX
ANDL $3, BX
REP; MOVSL
MOVL BX, CX
REP; MOVSB
MOVL to+0(FP),AX
RET
/*
* whole thing backwards has
* adjusted addresses
*/
back:
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