Date: Thu, 28 Jun 2001 21:04:41 +0300
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
Sender: halo1 AT zahav DOT net DOT il
To: Ravi DOT M AT smartm DOT com
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CC: djgpp AT delorie DOT com
In-reply-to: <200106281344.QAA14266@is.elta.co.il> (Ravi.M@smartm.com)
Subject: Re: help
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[Please keep this discussion on the news group.]

> From: Ravi DOT M AT smartm DOT com
> Date: Thu, 28 Jun 2001 19:16:57 -0700
> 
> this is the program i want to debug.

What exactly is the problem?  Which parts of the program don't work,
and how do they fail?  I can't debug a program from far away without
even knowing how does it fail, can I?

Also, what command-line arguments did you try to pass to the program?

>   offset=dos_mem_init(addr,size);        /* initialises the memory and returns the offset */ 
> 
>     for(i=0;i<offset;i++)
>       {
>          _farpokel(gselector,i,'a');    /* write something  to the allocated space */

This is not entirely correct: you go all the way to the last byte of
the allocated memory region, but write a full 32-bit dword (i.e., 4
bytes) there.  This means that the last 3 iterations through the loop
will certainly GPFault, because they exceed the limit of the
descriptor created for accessing this memory region.

The same problem exists in dos_read_from_mem.

If you want to read and write single bytes, use _farpokeb and
_farpeekb, not _farpokel and _farpeekl.