Chocolate Doom PSP

A simple port of Doom for the Sony PSP.

Motivation

Doom is one of the most widely ported games there is and there are even many PSP ports that already exist. The purpose of this project was not to reinvent the wheel, but to work with a codebase that is known to be extremely portable for the purposes of learning more about the porting process.

A project like this is small and allows me to learn and solve the various challenges that arise when porting any game to the PSP (or other platforms, to some extent). The skills learned are directly transferrable. Because of this, work on future game ports will consist entirely of overcoming game-specific challenges rather than getting hung up on the common issues that come with the territory.

Prerequisites

• You will need a PSP capable of running unsigned code. There are many guides available on how to install custom firmware. Alternately, you can sign your executable so it will run on an unmodified PSP. This port also works in PSP emulators.

Compiling

• Install the PSP toolchain
• Build SDL2, SDL2_mixer, and SDL2_net using the PSP toolchain (only SDL2 has a PSP Makefile, you will need to write your own for SDL2_mixer and SDL2_net)
• Use my PSP CMake toolchain file to generate a Makefile for Chocolate Doom
• Build Chocolate Doom for PSP by running make chocolate-doom

Running

• On your PSP, create a directory at ms0:/PSP/GAME/DOOM and copy EBOOT.PBP and a Doom WAD file to that location
• Navigate to the game using the PSP XMB menu and start it

PSP controls

• D-pad/joystick: movement
• Cross: fire
• Circle: use
• Square/Triangle: Next/previous weapon
• L/R: Strafe
• Start: Menu
• Select: Automap

Limitations

• No sound. It works but I have disabled it since every time a new (uncached) sound loads, the game freezes for several seconds. An improvement could be to cache them all on startup but it cannot be done naively due to memory constraints.

Chocolate Doom

Chocolate Doom aims to accurately reproduce the original DOS version of Doom and other games based on the Doom engine in a form that can be run on modern computers.

Originally, Chocolate Doom was only a Doom source port. The project now includes ports of Heretic and Hexen, and Strife.

Chocolate Doom’s aims are:

• To always be 100% Free and Open Source software.
• Portability to as many different operating systems as possible.
• Accurate reproduction of the original DOS versions of the games, including bugs.
• Compatibility with the DOS demo, configuration and savegame files.
• To provide an accurate retro “feel” (display and input should behave the same).

More information about the philosophy and design behind Chocolate Doom can be found in the PHILOSOPHY file distributed with the source code.

Setting up gameplay

For instructions on how to set up Chocolate Doom for play, see the INSTALL file.

Configuration File

Chocolate Doom is compatible with the DOS Doom configuration file (normally named default.cfg). Existing configuration files for DOS Doom should therefore simply work out of the box. However, Chocolate Doom also provides some extra settings. These are stored in a separate file named chocolate-doom.cfg.

The configuration can be edited using the chocolate-setup tool.

Command line options

Chocolate Doom supports a number of command line parameters, including some extras that were not originally suported by the DOS versions. For binary distributions, see the CMDLINE file included with your download; more information is also available on the Chocolate Doom website.

Playing TCs

With Vanilla Doom there is no way to include sprites in PWAD files. Chocolate Doom’s ‘-file’ command line option behaves exactly the same as Vanilla Doom, and trying to play TCs by adding the WAD files using ‘-file’ will not work.

Many Total Conversions (TCs) are distributed as a PWAD file which must be merged into the main IWAD. Typically a copy of DEUSF.EXE is included which performs this merge. Chocolate Doom includes a new option, ‘-merge’, which will simulate this merge. Essentially, the WAD directory is merged in memory, removing the need to modify the IWAD on disk.

To play TCs using Chocolate Doom, run like this:

chocolate-doom -merge thetc.wad

Here are some examples:

chocolate-doom -merge batman.wad -deh batman.deh vbatman.deh  (Batman Doom)
chocolate-doom -merge aoddoom1.wad -deh aoddoom1.deh  (Army of Darkness Doom)

Other information

• Chocolate Doom includes a number of different options for music playback. See the README.Music file for more details.

• More information, including information about how to play various classic TCs, is available on the Chocolate Doom website:

  https://www.chocolate-doom.org/

  You are encouraged to sign up and contribute any useful information you may have regarding the port!

• Chocolate Doom is not perfect. Although it aims to accurately emulate and reproduce the DOS executables, some behavior can be very difficult to reproduce. Because of the nature of the project, you may also encounter Vanilla Doom bugs; these are intentionally present; see the NOT-BUGS file for more information.

  New bug reports can be submitted to the issue tracker on Github:

  https://github.com/chocolate-doom/chocolate-doom/issues

• Source code patches are welcome, but please follow the style guidelines - see the file named HACKING included with the source distribution.

• Chocolate Doom is distributed under the GNU GPL. See the COPYING file for more information.

• Please send any feedback, questions or suggestions to [email protected]. Thanks!