README.GP2X

GP2X port done by Stuart Bingë <skbinge@gmail.com>, July-August 2006

Based off the Powermanga 0.80 source, available from
http://linux.tlk.fr/games/Powermanga/ (GPL licensed).

This port *should* conform to the GP2X Common User Interface Recommendations
(http://wiki.gp2x.org/wiki/Common_User_Interface_Recommendations), however the
assignments can easily be changed in the handleGP2XButtons() method in
sdl_tlk.cpp (line 454) if needs be. Well, easily enough if you have access to a
GP2X build environment ;-) Mapping from the GP2X button codes to Powermanga's
internal control array is probably the worst bit of it all.


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This port, while relatively straightforward, did cause a couple of headaches.
I've documented them here to possibly help others when porting apps to the GP2X:

 * Beware of filename case issues! GP2X runs Linux internally, which is
    case-sensitive, however the SD cards are formatted with FAT, which has its
    own file case ... "issues", especially with all-uppercase files. It's
    probably best/easiest to just convert all filenames to lowercase on the
    filesystem and in the code.

 * Beware of endianess issues when performing binary I/O on the filesystem -
    it's best to use constructs such as found in SDL_endian.h to ensure your
    code is endian-independant.

 * Games that use SDL_Mixer generally use a large chunksize parameter when
    calling Mix_OpenAudio(), such as 4096, which, when ported to the GP2X,
    causes the sound to lag substantially. Good values to try for this
    parameter on the GP2X are 64 or 128 - the smaller the better (more
    synchronised sounds), however make it too small and the sound will start
    to stutter...

 * The GP2X's SDL_Mixer doesn't play XM mod files natively... so you'll
    probably have to convert any XM's (or any other mods?) to WAV/OGG/MP3 etc.

 * Debugging without a serial connection can be a real pain, as you constantly
    bash your head against a brick wall when you attempt to run a fresh
    compile... only to have it go black and never come back. If you're doing
    any sort of development work for the GP2X I highly recommend getting USB
    networking set up (over the standard USB cable that comes with the GP2X)
    so that you can simply telnet in to the GP2X and run programs/see output
    from there. If you're feeling more adventurous you can either get an
    EXT->Serial connection, or get the USB gadget kernel module for the GP2X
    and connect to it as a "modem" through minicom/hyperterminal, etc.

 * Debugging with a card reader is also a real pain. Combine this with no
    USB networking/serial connection and you're guaranteed not only to wear out
    your sanity, but your nice shiny new SD card as well!

 * Porting source written in a foreign language can be rather challenging ;-)
    Babelfish comes in really handy here...

If you're still reading this, please consider porting something over to the
GP2X yourself, or better yet write your own game! The GP2X, while seriously
awesome as-is, has huge potential not only with emulators but also with the
large collection of open source games out there. Check out
http://happypenguin.org/ for a list, and get coding! :-)

So long, and enjoy Powermanga!
 - Stu