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|
TEXT memcpy(SB), $0
MOVL n+8(FP), R0 /* count */
BEQ return
BGT ok
MOVL 0, R0
ok:
MOVL s1+0(FP), A2 /* dest pointer */
MOVL s2+4(FP), A1 /* source pointer */
CMPL A2,A1
BHI back
/*
* byte-at-a-time foreward copy to
* get source (A1) alligned.
*/
f1:
MOVL A1, R1
ANDL $3, R1
BEQ f2
SUBL $1, R0
BLT return
MOVB (A1)+, (A2)+
BRA f1
/*
* check that dest is alligned
* if not, just go byte-at-a-time
*/
f2:
MOVL A2, R1
ANDL $3, R1
BEQ f3
SUBL $1, R0
BLT return
BRA f5
/*
* quad-long-at-a-time forward copy
*/
f3:
SUBL $16, R0
BLT f4
MOVL (A1)+, (A2)+
MOVL (A1)+, (A2)+
MOVL (A1)+, (A2)+
MOVL (A1)+, (A2)+
BRA f3
/*
* cleanup byte-at-a-time
*/
f4:
ADDL $15, R0
BLT return
f5:
MOVB (A1)+, (A2)+
SUBL $1, R0
BGE f5
BRA return
return:
MOVL s1+0(FP),R0
RTS
/*
* everything the same, but
* copy backwards
*/
back:
ADDL R0, A1
ADDL R0, A2
/*
* byte-at-a-time backward copy to
* get source (A1) alligned.
*/
b1:
MOVL A1, R1
ANDL $3, R1
BEQ b2
SUBL $1, R0
BLT return
MOVB -(A1), -(A2)
BRA b1
/*
* check that dest is alligned
* if not, just go byte-at-a-time
*/
b2:
MOVL A2, R1
ANDL $3, R1
BEQ b3
SUBL $1, R0
BLT return
BRA b5
/*
* quad-long-at-a-time backward copy
*/
b3:
SUBL $16, R0
BLT b4
MOVL -(A1), -(A2)
MOVL -(A1), -(A2)
MOVL -(A1), -(A2)
MOVL -(A1), -(A2)
BRA b3
/*
* cleanup byte-at-a-time backward
*/
b4:
ADDL $15, R0
BLT return
b5:
MOVB -(A1), -(A2)
SUBL $1, R0
BGE b5
BRA return
|
