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procedure _CopyMemory(P1, P2: Pointer; Len: Integer); assembler;
asm
PUSH ESI
PUSH EDI
MOV EDI,EAX { destination address }
MOV ESI,EDX { source address }
MOV EAX,ECX
CMP EDI,ESI
JA @@down
JE @@exit
SAR ECX,2 { copy count DIV 4 dwords }
JS @@exit
REP MOVSD
MOV ECX,EAX
AND ECX,03H
REP MOVSB { copy count MOD 4 bytes }
JMP @@exit
@@down:
LEA ESI,[ESI+ECX-4] { point ESI to last dword of source }
LEA EDI,[EDI+ECX-4] { point EDI to last dword of dest }
SAR ECX,2 { copy count DIV 4 dwords }
JS @@exit
STD
REP MOVSD
MOV ECX,EAX
AND ECX,03H { copy count MOD 4 bytes }
ADD ESI,4-1 { point to last byte of rest }
ADD EDI,4-1
REP MOVSB
CLD
@@exit:
POP EDI
POP ESI
end;