Mail Archives: djgpp/1999/09/30/18:31:50

From: "Damian Yerrick" <web DOT poison AT pineight DOT 8m DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Creating Allegro Bitmap from Binary Data
Date: Thu, 30 Sep 1999 13:14:25 -0500
Organization: Rose-Hulman Institute of Technology
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References: <37f39fd3 DOT 0 AT energise DOT enta DOT net>
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Tony Friery <tony AT basoft DOT enta DOT net> wrote in message
news:37f39fd3 DOT 0 AT energise DOT enta DOT net...
> Hi there,
> I am currently writing an Emulator for the (now near-vintage) Sharp MZ-80B
> and have a question regarding the Screen-Generator Code.
> The Graphical Resolution is 2 simultaneous mono-planes of 320x200, and
> normally 40x25 using 8x8 font (Conveniently :) ) There is also an
> mode which means an effective resolution of 640x400 which is what I have
> chosen as the graphics mode.

Sounds like it uses a CGA-ish system.

> At the moment, I use 5 bitmaps (eg FONTRAM, TEXTRAM, VID1RAM, VID2RAM,
> TEMPRAM) in various resolutions and use a combination of stretch_blit,
> and masked_blit to get them onto the screen.
> With the text, this is normally OK (I pre-stretch into a temporary bitmap
> beforehand as it will always be y*2 stretched anyway in order to save
> overhead) but I need an efficient way of writing an 8-bit value

I don't know about video RAM, but I know that normal memory bitmaps
created with create_bitmap() can be accessed thus:

BITMAP *foo;
char *pixelLine;
int x, y;

for(y = 0; y < height; y++)
  pixelLine = foo->line[y];
  for(x = 0; x < width; x++)
    pixelLine[x] = 69;

Once you have your pixels in a bitmap, you can blit() it to the screen.

Damian Yerrick

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