Path: utzoo!attcan!uunet!mcvax!unido!tub!tmpmbx!netmbx!alderaan
From: alderaan@netmbx.UUCP (Thomas Cervera)
Newsgroups: comp.sys.atari.st
Subject: Re: Questions about ST Video Ram
Message-ID: <1135@netmbx.UUCP>
Date: 5 Aug 88 11:00:15 GMT
References: <535@skywest.UUCP> <529@laura.UUCP>
Organization: netmbx Public Access Unix, Berlin, West Germany
Lines: 32

In article <529@laura.UUCP>, jf@laura.UUCP (Jan Hinrich Fessel) writes:

> In article <535@skywest.UUCP> brenes@skywest.UUCP (Erasmo Brenes) writes:
> >Hello, this is a question to the ST graphic 'gurus':
> >question is: If the Shifter expects the video ram to start at 32K boundaries,
> >then how do I get MWC, or any C program to allocate a 32Kb buffer starting in
> >a 32Kb boundary in an efficient manner?  An initial thought was to use Malloc()
> >to allocate 64Kb and then only use the 32Kb which start in a 32Kb boundary,
> >but this method is too wasteful. There's got to be a better way, isn't there?
> >

> Me no graphic-guru, but as far as I know the buffer has to be aligned on a
> 512 byte boundary, so Malloc() is wasting only up to 511 bytes.
> Hope thats correct, i haven't tried it yet:-)
> 

Not quite right. As I know, (would be more logical) the video bitmap graphics
array must start at a page (256b) boundary. So, substract #256 from all values
given by Jan-Hinrich and it will be ok, I guess ...

  With my best wishes for your success -- alderaan.


--

alderaan
OP RKOpdp (RSTS/E)
FB Mathematik/Informatik
RKO Berlin

Dieffenbachstrasze 60-61
1000 Berlin 61