[Lazarus] RE : Convert assembler to Pascal

[Ludo Brands]

Procedure XorMemPrim(var Mem1;  const Mem2;  Count : Cardinal);
Var i:integer;
  p1,p2:pointer;
Begin
p1:=@Mem1;
p2:=@Mem2;
for i:=1 to count div 4 do
  begin
  pdword(p1)^:=pdword(p1)^ xor pdword(p2)^;
  p1:=p1+4;
  p2:=p2+4;
  end;
For i:=1 to count mod 4 do
  begin
  pbyte(p1)^:=pbyte(p1)^ xor pbyte(p2)^;
  p1:=p1+1;
  p2:=p2+1;
  end;
End;

Ludo
> procedure XorMemPrim(var Mem1;  const Mem2;  Count : 
> Cardinal); register; asm
>   push esi
>   push edi
> 
>   mov  esi, eax         //esi = Mem1
>   mov  edi, edx         //edi = Mem2
> 
>   push ecx              //save byte count
>   shr  ecx, 2           //convert to dwords
>   jz   @Continue
> 
>   cld
> @Loop1:                 //xor dwords at a time
>   mov  eax, [edi]
>   xor  [esi], eax
>   add  esi, 4
>   add  edi, 4
>   dec  ecx
>   jnz  @Loop1
> 
> @Continue:              //handle remaining bytes (3 or less)
>   pop  ecx
>   and  ecx, 3
>   jz   @Done
> 
> @Loop2:                 //xor remaining bytes
>   mov  al, [edi]
>   xor  [esi], al
>   inc  esi
>   inc  edi
>   dec  ecx
>   jnz  @Loop2
> 
> @Done:
>   pop  edi
>   pop  esi
> end;
> 
> Thanks in advance,
> -- 
> Leonardo M. Ramé
> http://leonardorame.blogspot.com
> 
> --
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