DOS - Modern Development Tools

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Sample makefiles
- 286 / Real mode target
- 386 / Protected mode target

OpenWatcom

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Sample makefile

DJGPP / GCC

Allegro 4

Homepage
Documentation
- Official documentation at liballeg.org - downloadable versions only
- Alternative documentation at allegro.cc
Downloads
- allegro-4.2.3.1.djgpp.bin.tar.bz2
- The above includes Allegro 4.2.3.1 built and patched for DJGPP, with all example code, normal, debug and profile library versions and html docs. This unpacks to /opt/toolchains/x86/allegro-djgpp.
- CWSDPMI.EXE (at the official homepage or the information on Wikipedia)
- You need cwsdpmi.exe, above, (or an equivalent DPMI server) in order for DJGPP binaries to run on DOS.

How to build on modern compilers.

Download 4.2.3.1 source
Unpack
Configure for DJGPP cross-compilation (run 'fix.sh djgpp')

Next you have to edit xmake.sh to pick up your DJGPP install. In my case it was setting the two variables XC_PATH and XPREFIX to the following:

xmake.sh

XC_PATH=/opt/toolchains/x86/djgpp/bin
XPREFIX=i586-pc-msdosdjgpp-

Next edit makefile.dj to set a compatibility option for the modern GCC compiler (the '-fgnu89-inline' directive). If you don't, things look like they work until you try to link against Allegro and your code will fail to compile due to duplicate symbol errors (there are a lot of inline defines in the Allegro headers, which are deprecated on C99 syntax):

makefile.dj

TARGET_OPTS = -fgnu89-inline -O2 -funroll-loops -ffast-math

Finally, there is a bug in one of the graphics drivers that comes with the 4.2.3.1 release, and it results in two missing symbols when compiled with GCC. You need to edit src/misc/vbeaf.c and add them. Just before the following lines:

src/misc/vbeaf.c

* the video driver structure */
GFX_DRIVER gfx_vbeaf =
{

Change it to show the following:

src/misc/vbeaf.c

int int_ds;
int saved_ds;

/* the video driver structure */
GFX_DRIVER gfx_vbeaf =
{

Now you are ready to compile Allegro from source:

./xmake.sh lib
cp -a include /to/where/you/want/the/allegro/headers
cp lib/djgpp/lib*.a /to/where/you/want/the/allegro/libs

You can optionally build the demo application as well:

./xmake.sh demo

However, the examples don't get built via the cross compile process, so they need to be built manually:

cd allegro-4.2.3.1
cd examples
for src in *.c; do
  i586-pc-msdosdjgpp-gcc -I/to/where/you/want/the/allegro/headers -g -O2 -o ${src%.c} $src /to/where/you/want/the/allegro/libs/liballeg.a -lm
done