From: Shawn Hargreaves Newsgroups: comp.os.msdos.djgpp Subject: Re: Allegro+24bit mode Date: Tue, 24 Mar 1998 19:20:42 +0000 Organization: None Message-ID: References: <35155D83 DOT 34A12BC6 AT teccart DOT qc DOT ca> <3515B560 DOT 16430355 AT concentric DOT net> <35173706 DOT 6036C833 AT earthling DOT net> NNTP-Posting-Host: talula.demon.co.uk MIME-Version: 1.0 Lines: 26 To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Precedence: bulk Chris Wahlen writes: >I'm beginning to think that this may be some sort of bug in allegro's code - >using handwritten VESA routines I can get to these modes, but with allegro I >can't. Allegro has some restrictions on how the video memory must be organised, in particular that it doesn't allow a bank switch to occur partway through a scanline. This can sometimes require adjustments to the virtual screen width, and often causes problems on buggy VESA drivers that don't handle these calls properly (particularly in 24 bit mode due to the nasty odd alignments). These troubles can usually be fixed by getting UniVBE, which handles all the required routines correctly. Even better is to use a linear framebuffer mode, in which the whole problem goes away because there are no longer any bank switches at all. If you are already using UniVBE in a linear framebuffer mode this obviously doesn't apply: should this be the case, I would be very interested if you could do some experimenting and try to find out how my code differs from your routines that work properly... -- Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/ "Pigs use it for a tambourine" - Frank Zappa