BuildingDOSBox

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Building your own version of DOSBox

Why to do this?
Because any resource-intensive program can benefit greatly from optimization for your exact processor.
System Requirements states that a P3 1Ghz can emulate a 3/486 - early dos games. I have compiled Dosbox and SDL myself for this processor, 1Ghz P3, and I can run games from 95/96 OK (Caesar 2, C&C: Red Alert). So, if you have the skill, the performance increase is recommended.


1. Grab the source

First, grab the latest version of the DOSBox source code. A fairly often updated SVN-Dump can be found at: http://source.dosbox.com/dosboxsvn.tgz

Download it and extract it to a separate directory.

2. SDL

DOSBox uses SDL (Simple DirectMedia Layer) to access your graphics and sound hardware, so you'll need to download it as well. Grab the latest source at

http://www.libsdl.org/

and extract to a separate directory.

When working on Windows, you might want to save a lot of effort and just use the SDL (and optionally SDL_net) .DLL files included with the latest official DOSBox release, as compiling SDL with full options (e.g. DirectX support) is a bit involved. There are also pre-built .DLL files on the SDL web site (Runtime Libraries -> Win32) that you can try at

http://www.libsdl.org/download-1.2.php

Note that as of 12 Dec 2004, ddraw (DirectDraw) rendering mode will not work in DOSBox unless you either use the SDL.dll included with the latest version of DOSBox, or build your own SDL.dll with the changes mentioned in the "Compiling SDL" section below.

3. Compiling environment

When working on Windows, you'll most likely need a compiling environment. We suggest using the combination of MinGW and MSYS, which can be found at

http://prdownloads.sf.net/mingw/

You'll need to download both the latest MinGW and MSYS. After downloading, install MinGW and MSYS (in this order). The MSYS-Installer should ask for the installation directory of MinGW, so you should pick the path where you installed it. After the installation, run the MSYS.BAT and you should see a unix-like command prompt.

Warning! The latest MinGW comes with version 4.7.2 of gcc and g++. For some people this will end up resulting in a version of DOSBox that compiles fine but hangs when issued any command, like the "mount" command. If this is happening to you, try using an older version of gcc like so:

Go into the MinGW shell and do:

mingw-get remove gcc
mingw-get remove g++
mingw-get install gcc=4.5.2-1
mingw-get install g++=4.5.2-1

Also, if you do use an older version of gcc/g++, you'll need to make sure that DOSBOX.EXE, when run, is in a directory with compatible gcc/g++ DLLs. The easiest way to insure this is to copy libgcc_s_dw2-1.dll and libstdc++-6.dll from the MinGW/bin directory to your DOSBOX directory.

4. Compiling SDL

Navigate to the directory where you extracted the SDL-source (using unix commands) and type

./configure
make
make install

Some MinGW-specific info on compiling SDL under Windows is available at

http://www.libsdl.org/extras/win32/mingw32/README.txt

If you are having trouble with a message like 'no acceptable ld found in $PATH' try 'export LD=/c/gxx-2.95.2/bin/ld.exe' (or wherever you have the exe; GCC 2.95 in this case).

Also, if you have trouble getting ddraw (DirectDraw) working in DOSBox, see this post on the DOSBox forum for a possible fix:

http://vogons.zetafleet.com/viewtopic.php?p=48050&highlight=#48050

4b. SDL-net (optional)

If you want to benefit from DOSBox's Modem-Emulation or IPX-Support, you'll also need the SDL-net library, which can be found at

http://www.libsdl.org/projects/SDL_net/

Download, extract, and compile as you did with SDL.

If you skipped building your own SDL.dll, you can use the one included with the latest official release of DOSBox or you can get a SDL_net win32 binary (.DLL) release on the SDL web site at the URL above.

5. Compiling DOSBox

After compiling you'll need to adjust the PATH variable to point at the directory where the freshly built SDL-Library can be found.

Note: if you want to use SDL-net, do the same with that library.

Then, change to the directory where you extracted the DOSBox-Source and type

./autogen.sh
./configure
make

to compile DOSBox. If everything worked, you should have a DOSBOX.EXE in the ./src - directory.

6. Running

The easiest way to run the new executable is to copy it (and your fresh SDL.dll and maybe even the SDL_net.dll) to the installation-directory of a non-SVN-version of DOSBox. That way, you have the needed directory structure and configuration files.

Example for Building DOSBox 0.71 on OpenSUSE 10.2 Linux

-Remove the existing DOSBox version if you have it.

-Obtain and extract the DOSBox source code.

-SUSE linux 10.2 already has SDL and alsa installed, but you need to install the SDL-devel package and alsa-devel package (for header files and libs).

-Obtain the SDL_Sound src from http://icculus.org/SDL_sound/downloads. Extract the source somewhere.

Run configure --with-sdl-prefix=/usr/lib64 --with-sdl-exec-prefix=/usr
make
make install (need to be root)

-OK, now you have everything you need to compile DOSBox. cd to your DOSBox directory, then run this at the shell:

export CPPFLAGS="-I/usr/local/include/SDL"
export LDFLAGS="-L/usr/local/lib"
configure --with-sdl-prefix=/usr/lib64 --with-sdl-exec-prefix=/usr --with-alsa-prefix=/usr/lib64
   --with-alsa-inc-prefix=/usr/include/alsa
make
make install (need to be root).

-The reason for the shell variables is that it seemed to be the only way configure could find the files it needed. There aren't any config options to find the SDL_sound library, and I tried giving it -libdir= and -includedir=, but that didn't work.