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TEXT memmove(SB), $0
MOVL p1+0(FP), DI
MOVL DI, AX /* return value */
MOVL p2+4(FP), SI
MOVL n+8(FP), BX
CMPL BX, $0
JGT _ok
JEQ _return /* nothing to do if n == 0 */
MOVL $0, SI /* fault if n < 0 */
/*
* check and set for backwards:
* (p2 < p1) && ((p2+n) > p1)
*/
_ok:
CMPL SI, DI
JGT _forward
JEQ _return /* nothing to do if p2 == p1 */
MOVL SI, DX
ADDL BX, DX
CMPL DX, DI
JGT _back
/*
* copy whole longs
*/
_forward:
MOVL BX, CX
CLD
SHRL $2, CX
ANDL $3, BX
REP; MOVSL
/*
* copy the rest, by bytes
*/
JEQ _return /* flags set by above ANDL */
MOVL BX, CX
REP; MOVSB
RET
/*
* whole thing backwards has
* adjusted addresses
*/
_back:
ADDL BX, DI
ADDL BX, SI
STD
SUBL $4, DI
SUBL $4, SI
/*
* copy whole longs
*/
MOVL BX, CX
SHRL $2, CX
ANDL $3, BX
REP; MOVSL
/*
* copy the rest, by bytes
*/
JEQ _return /* flags set by above ANDL */
ADDL $3, DI
ADDL $3, SI
MOVL BX, CX
REP; MOVSB
_return:
RET
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