[fpc-pascal]Intel ASM syntax problem

[AITOR.SM]

Ooops!!
You are entirely right! 32-bit world!

Let me explain something else about this program. This is a piece of 
snippet taken from SWAG, as it is a quite detailed drive identification 
code, so I didn't write it myself. I simply tried to compile under FPK, 
just forgetting that I am doing these seg:ofs calls and the like.

Well, I don't believe this will compile even if I change bx by ebx. My 
solutions could be:

(a) any of you has a piece of code to detect fd/cd/hd/ram/net disks 
under GO32V2
(b) as this is a *very* small program, I will compile it under TP 
(which is a pitty, I expected to release my program entirely compilable 
under FreePascal)

Well, thanks!
Aitor

----- Mensaje Original -----
De: Jonas Maebe <jonas at zeus.rug.ac.be>
Fecha: Lunes, Junio 25, 2001 5:37 pm
Asunto: Re: [fpc-pascal]Intel ASM syntax problem

> 
> On maandag, juni 25, 2001, at 05:17 , Aitor Santamaria Merino wrote:
> 
> >  am trying to compile this (which compiles under TP): (using asm and
> > {$ASMMODE Intel}):
> >
> > (66) mov word ptr ds:ControlBlk25[bx].StartSector,ax
> > (67) mov word ptr ds:ControlBlk25[bx].StartSector[2],ax
> >
> >
> > where
> >  ControlBlk25  = record   { control block for INT 25 extended 
> call }
> >    StartSector : LongInt; { start sector to read }
> >    Count       : Word;    { number of sectors to read }
> >    BufferOffs  : Word;    { data buffer offset }
> >    BufferSeg   : Word;    { data buffer segment }
> >  end;
> >
> >
> > The problem appears when it reaches the [bx]:
> > drvscan.pp(66,18) Fatal: Syntax error, [ expected but identifier 
> found>
> > Any alternative/correction?
> 
> First of all: you will most likely have to rewrite almost all your 
> assembler routines, because you now work in a 32bit memory model. 
> This 
> means that anything that  uses segments (including lds/les) or 
> memory 
> address expressions containing registers (such as the above) will 
> have 
> to change. The reason is that there are no segments anymore, only 
> selectors (which you normally can ignore, you can assume all of 
> your 
> data is in the DS selector, except if you need to access video 
> memory or 
> so) and all offsets are 32bits (so you'd need at least ebx instead 
> of bx 
> in the above example).
> 
> Second, you won't be able to pass a data structure from you 
> program to a 
> Dos interrupt call the way you are trying it, because Dos can only 
> work 
> with the first megabyte of memory and in segment:offset format, 
> while 
> FPC programs work with all memory in your computer and that data 
> structure most likely lies way above the first megabyte. You will 
> need 
> the dosmemput/dosmemget/global_dos_alloc/global_dos_free routines 
> from 
> the go32 unit. I suggest you throughly read the docs of that unit 
> before 
> attempting things like this
> 
> Third: there may indeed be bugs in the assembler reader. It should 
> compile if you change it to
> 
> mov word ptr ControlBlk25[ebx].StartSector,ax
> 
> but I'm not sure (you definitely need a 32bit register as offset, 
> I 
> don't think we support the generation db 67h prefixes to allow 
> 16bit 
> registers in memory expressions).
> 
> 
> Jonas
> 
> _______________________________________________
> fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org
> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
> 

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