Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!cmcl2!yale!wallman From: wallman@yale.UUCP Newsgroups: comp.sys.atari.st Subject: AES in interrupts (was RE: ?strange bug) help wanted Message-ID: <19536@yale-celray.yale.UUCP> Date: Wed, 25-Nov-87 21:46:16 EST Article-I.D.: yale-cel.19536 Posted: Wed Nov 25 21:46:16 1987 Date-Received: Sun, 29-Nov-87 12:21:48 EST Sender: root@yale.UUCP Reply-To: wallman@koala.UUCP (Natuerlich!) Organization: Yale University Computer Science Dept, New Haven CT Lines: 43 Moshe Braner's answer about interrupt redirection has reminded me of one of my big unsolved problems. The task was to create a little resident gadget that fooled well- behaved programs into thinking they were running in Hi-Res. I tried to patch into the XBIOS trap (successfully) intercept only Getrez() calls, passing by the rest to the OS (successfully) and returning a value to the calling procedure (successfully). Then I tried calling a form_alert() from within the TRAP (unsuccessfully). The problem here was that AES needs to be called from usermode (*). I set up a rather elaborate scheme that involved using a free TRAP and a handsomely sized user-stack. Finally I got it to work ONCE. The alert popped up, I could choose a resolution and the appropriate value was returned. But only ONCE, the next time it crashed. I don't know why... It sounds like a stack overflow but I allocated 4K and that sounds like plenty, especially for a small form_alert. Has anyone done something similiar ? Or can someone give a possible explanations why it doesn't/ can't /never will work ? Thanks very much in advance... Footnote : (*) Strangely enough all the stuff written in assembler such as XBIOS & BIOS are usually uncomplicated and relatively bug free, whereas the stuff written in C like AES and VDI (I don't know about GEMDOS but I fear the worST) is either buggy or sloppily written and even worse incomplete. :-| <<<>>>> <.......................IIII, ..< <......III, ..........IXI, .....< <.....IXIIXI, ......IXI,, ......< <....IXI,,IXI, ...IXI,, ........< <...IXI,, .IXI, IXXI,, .........< <..IXXI,, ..IXXXXXI,, ..........< <.IXXI,, ....IXXXI,, ...........< >>>>>>>> wallman@yale WALLMANN@CTSTATEU.BITNET