[fpc-devel] Compiling Intel assembly code in 32 and 64 bit.

kyan alfasud.ti at gmail.com
Thu Jan 26 15:23:13 CET 2012

Hello everyone,

I am trying to compile the following code:

procedure XORBuff(I1, I2: Pointer; Size: Integer; Dest: Pointer);
       AND   ECX,ECX
       JZ    @@5
       PUSH  ESI
       PUSH  EDI
       MOV   ESI,EAX
       MOV   EDI,Dest
@@1:   TEST  ECX,3
       JNZ   @@3
@@2:   SUB   ECX,4
       JL    @@4
       MOV   EAX,[ESI + ECX]
       XOR   EAX,[EDX + ECX]
       MOV   [EDI + ECX],EAX
       JMP   @@2
@@3:   DEC   ECX
       MOV   AL,[ESI + ECX]
       XOR   AL,[EDX + ECX]
       MOV   [EDI + ECX],AL
       JMP   @@1
       POP   EDI
       POP   ESI

in FPC for Win64 and I get an error (invalid opcode/operand
combination) in the lines that PUSH and POP registers. If I replace
the 32-bit regs with their 64-bit "R" equivalents (PUSH RSI instead of
PUSH ESI) it compiles but I suppose it will not compile for Win32.

So apart from the apparent solution of {$ifdef cpu64}'ing is there any
other way to make this compile for 64bit (and Delphi XE if possible,
which is 32bit) without conditional compilation? By searching through
the FPC source directory I have noticed that units with Intel assembly
code that contains PUSH/POP instructions use the "E" regs without
ifdef'ing. How do these compile?

Thank you in advance and bare with me, I am by no means an assembly expert.

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