Date: Thu, 27 Apr 1995 03:44:35 -0300 (ADT)
From: Bill Davidson <bdavidson AT ra DOT isisnet DOT com>
Subject: Re: Chaining real-mode interrupts
To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu


More followups on the great hardware interrupt bug hunt:

I ran the test8.exe program from pctime12.zip with my GO32 env var set to 
'topline'.  The program hit the first call to getkey() (before chaining 
the timer interrupt) and sat there with 'R' on the top line.  I pressed a 
key, and got UnsuppUsuppUnsuppUnsupp... all over my screen, then the 
machine rebooted.  Without 'topline', it runs fine.  The program is only 
hooking the timer interrupt; is there some weird interaction between go32 
and the timer interrupt?  (I performed this test several times.)

As for my own code, I tried the -S option to gcc and looked over the 
resulting assembler (also had -O2 in there).  I noticed that in my 
handler function, where it called memset() and where it called 
_go32_dpmi_simulate_fcall_iret(), there was no cleaning-up of the stack 
on return.  I confess that I am not up on 386+ assembler (I learned 8088 
assembler then switched to C); I think the 'leave' command does the stack 
cleanup (?), but it still looked wrong to me, especially in a handler 
function.  So I recompiled the module without any optimization, relinked, 
and the program ran pretty good.  The keyboard handler still seems to be 
a problem, but at least I am getting some (unstable) results!

Any thoughts/ideas/feedback welcome.

Bill