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From: svincent AT zippy DOT sonoma DOT edu (Sam Vincent)
Newsgroups: comp.os.msdos.djgpp
Subject: Hooking Real-mode Ints??
Date: 16 Oct 1995 21:02:28 GMT
Organization: Information Resources and Technology
Lines: 37
Nntp-Posting-Host: zippy.sonoma.edu
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway: from newsgroup comp.os.msdos.djgpp

Hi there,

Is there any way to hook a real mode interrupt under
djgpp V 2 (beta 2)..

I've hooked the prot mode serial interrupt and have used assembly
to avoid the wrappers..  and it works fine..
(For those of you wondering how to do this..  just push ds,
load ds with the value of cs:___djgpp_ds_alias, do your stuff...
then pop ds back..   it should work fine and you can use the 4k
locked stack thats already provided)

However.. I'm still missing interrupt..  transmissions come through
really messed up..  I get maybe half the characters which are sent..
I believe this is due to the dpmi reflection from real to protected mode
of any interrupts...   This is probably very slow and causes a few
characters to come in before i actually get the interrupt..
(i have locked the comm port at 115200)

Is there any way I can tell it to use a routine in real mode that i have
provided?  It wouldnt be hard to allocate dos space and copy a
function there which should work in real mode..  but could I 
get it to stop reflecting everything back to my protected mode
handler..   this reflection just takes WAY too much time...

Thanks,

Sam



Btw...   I'm attempting to put together an asynchronous comm port library
for DJGPP V2..  so for it works with comm ports 1-4 at speeds up to
38400 locked...   This is still unacceptable to me as a 28.8k modem
with full compression can give a throughput of quite a bit more..
Lemme know if you're interested in it...