From: DavMac AT iname DOT com (Davin McCall)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: DPMI memory allocation
Date: Fri, 05 Nov 1999 04:33:07 GMT
Organization: Monash Uni
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[posted and emailed]

Re: your post below.

Sounds like a classical case where interrupt handlers are not being
locked (and can therefore be swapped to disk). This causes problems
when the interrupt occurs when DOS is busy, as to swap in the
interrupt handler code, a DOS call must be made (and DOS is not
generally re-entrant).

Another thing to watch: Are you trying to perform a disk/file
operation from within an interrupt handler? This is another thing
which should generally be avoided, as DOS may be "busy" when the
interrupt occured.

Davin.


On Thu, 04 Nov 1999 19:57:46 GMT, Frederic Cazenave
<cazenave AT radar DOT mcgill DOT ca> wrote:

>Hi,
>
>I have written an application which allocates all
>the free pages of my memory to make a very large
>ring buffer. This buffer is filled when I receive
>an interrupt from an acquisition board. The main 
>program reads the buffer and displays the data on
>the screen using allegro lib. Everything works
>fine until I ask to save data. Then I open a file
>in binary, and each time a "Save_Buffer" is near
>to be full I write it on the file. This write 
>operation crashes my machine most of the time.
>If it works one time, I can ask to repeat the
>operation without problem. 
>The system works if instead of allocating all the
>free pages of the system I only allocate 50 kb.
>Even if I try with half of the free pages the system
>crashes.
>
>What's wrong ?????
>
>Thanks in advance
>Could you send me your answer by email too.

__________________________________________________________
       *** davmac - sharkin'!! davmac AT iname DOT com ***
my programming page: http://yoyo.cc.monash.edu.au/~davmac/