Far procedures and labels

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avcaballero

Joined: 02 Feb 2004
Posts: 203
Location: Madrid - Spain

avcaballero 23 Jun 2005, 13:55

I'm trying to do an interrupt handler and i need make a far procedure, something like this:

NuevaInt21h:
STI
PUSHF
DB 9Ah
OldInt21h DD 0
CLI
INC BYTE [NumTeclas]
IRET

But "LDS DX, OldInt21h" fails me. How can do it?

Thank you

23 Jun 2005, 13:55

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8357
Location: Kraków, Poland

Tomasz Grysztar 23 Jun 2005, 13:58

It should be:

Code:

LDS DX,[OldInt21h]

Also I'd prefer to not use DB to define opcodes:

Code:

STI
PUSHF
CALL FAR DWORD 0:0
LABEL OldInt21h DWORD AT $-4
CLI

Last edited by Tomasz Grysztar on 23 Jun 2005, 14:05; edited 2 times in total

23 Jun 2005, 13:58

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 23 Jun 2005, 14:00

privalov: now i'm confused. why "dword" ?

23 Jun 2005, 14:00

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8357
Location: Kraków, Poland

Tomasz Grysztar 23 Jun 2005, 14:01

16-bit far pointer is DWORD, 32-bit far pointer is PWORD.

Also definitions like this are correct:

Code:

ptr16 dd 0:0
ptr32 dp 0:0

where first 0 is 16-bit segment/selector and second 0 is 16/32-bit offset.

23 Jun 2005, 14:01

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