[fpc-pascal] Porting TP ASM to FPC ASM

[Marco van de Voort]

> Hope this is the right place to post..
> 
> I'm trying to convert some old Turbo Pascal asm to win32 fpc asm and 
> dont know where to start..
> 
> I'm compiling with -Sd and -Twin32 and {$asmmode intel}..
> 
> An example of what I'm trying to port:
> 
> procedure ClearFlag(var Flags: word; FlagMask: word); assembler;
> asm
> pop ax
> pop di
> pop es
> not ax
> and es:[di], ax
> end;
> 
> 
> If I change ax to eax, di to edi and es:[di] to [di], the code compiles 
> without warnings or errors, but I don't know if that's the right thing 
> to do.

No.  The calling conventions are different
 
> Any pointers, howtos, wiki pages, or whatever else that anyone could 
> offer to point me in the right direction would be greatly appreciated..

In this case, I think assembler is slower since it can't be inlined. Note
that TP uses a lot of assembler to workaround non-optimalisation.

IOW just do a :

procedure ClearFlag(var Flags: word; FlagMask: word);  inline;

begin
 flags:=flags and not flagmask
end;


(and possibly a {$inline on} globally for that unit)

... and hope this code was really rate-determining in speed, since you are
in for a speed boost :-)