mdl v1.0 (93/06/06)
-------------------

This is mdl, a TOS program to animate DL files (*.dl) on a monochrome Atari
ST. It is hard coded for 640x400 displays and uses Setscreen to do the
flicker mode thing (similar to my MGIF code). So, it won't run on color and
won't run on larger displays. It was a 1 day hack. If you don't like how it
works, I have thoughtfully provided source code for you to "make it right".

DL files are not that predominant (I have only a very few). There is little
documentation that I have found. mdl was based on xdl, a unix program for
running under X windows. I basically used xdl to get the file format.

Included in this distribution are the following files:

Name		Description
-------------------------------------------------------------------------
dl.5		compiled manpage for the DL file format (manpager format)
dl.ma5		nroff manpage for the DL file format
mdl.c		source code (known to work with GCC 1.4, MiNT libs PL 19)
flicker.c	more source code
makefile	makefile for mdl and manpages (check before running)
mdl.l		compiled manpage for mdl (manpager format)
mdl.man		nroff manpage for mdl
mdl.ttp*	executable
mkdl.c		source for a program to make a test .dl file (see src)
mkdl.ttp*	its executable
readme		this file
test.dl		test DL file
unix_xdl.zoo	the source for Xdl (unix X windows program)


There are (at least) 2 versions of DL files. mdl reads version 1 and 2 files.
It was, however, only tested on version 2 DL files and only those with
medium format (four 160x100 images per "screen).

Here is the file format as far as I can tell:

DL version 1 files:

size
bytes		desc
------------------------------------------------------------------------------
1		version number (1). image format (implicit) is 1 (medium)
20		title (XOR'ed with 0xff)
1		number of screens (nscr)
1		number of commands (ncmd)
1		? something to do with colormap and border colors
768		colormap (3 bytes per color, 256 colors)
320*200*nscr	data for each screen
ncmd		commands in an unknown format (see source code for details).
		the last command can be negative (unknown reason) and is to
		be ignored.


DL version 2 files:

size
bytes		desc
------------------------------------------------------------------------------
1		version number (2)
1		format (0=large320x200, 1=medium160x100)
20		title (XOR'ed with 0xff)
20		author (XOR'ed with 0xff)
1		number of screens (nscr)
1		number of commands (ncmd)
3		? something to do with colormap and border colors
768		colormap (3 bytes per color, 256 colors)
320*200*nscr	data for each screen (if format==0, single image per screen,
		if format==1, 4 images per screen)
2*ncmd		commands, little-endian (byte swapped 16-bit words). the last
		command can be negative (unknown reason) and is to be ignored.

Commands appear to be just a list of frames to display in a loop. For example,
given four frame images (0 through 3), the commands:

	0 1 2 3 2 3 2 3 2 1 2 1 2 1

can create an animation showing these frames in succession. You can thus have
far fewer actual bitmap images that "frames" in the animation loop.

Report bugs and enhancements to me if you want (rosenkra@convex.com).


Enjoy...

-Bill Rosenkranz
rosenkra@convex.com