Furball

Furball is a sound driver library for the Game Boy Advance.
It lets you play the Furnace DMG(+PCM) music on the GBA.

Well... not yet.

Development status

In short: Heavily WIP, expect breaking changes all the time.

• Only very basic DMG playback for now.
  • No effects, macros... nothing.
• No PCM support yet.

Usage

Building the library

Setup devkitARM, and call make -j$(nproc)
It'll build the lib/libfurball.a

Makefile options

If you change any Makefile option, you need to run make clean before running make.
Also, note that 1 is just an arbitrary value; It is enabled when the value is not empty.

• FB_MGBA_LOG_ENABLED := 1
  • Enables mGBA logging.
  • This also enables FB_ASSERT(...), as it uses mGBA log level FATAL under the hood.
• FB_MGBA_LOG_MAY_FATAL_CRASH := 1
  • If enabled, FB_LOG_MAY_FATAL(...) is FATAL (crash). Otherwise, it's ERROR (not crash).

Using the converter

You need Python 3.8+ to use the converter reliably.

# simple usage, it will create "my_song.c" in the same directory.
python converter/fb_converter.py --input my_song.fur
# specify output file path
python converter/fb_converter.py --input my_song.fur --output pre_existing_dir/result.c
# change the name of `const fb_music` C variable
python converter/fb_converter.py --input my_song.fur --c-var-name song_title

Playing the music

The converter's *.c output will look similar to this,
so you can declare the variable as extern to reference your song in your source.

#include "fb_music.h"
...
// declare this variable as extern in your source.
extern const fb_music my_song;
...

In order to play this, you'll need to call fb_update_vblank() in each VBlank.
I'm using ugba's interrupt handler for this example:

#include "furball.h"
#include "ugba/ugba.h"

extern const fb_music my_song;

int main(void) {
    // Initialize Furball with default settings.
    // See `struct fb_init_settings` in `include/fb_settings.h`
    fb_init(NULL);

    // Start playing with loop enabled.
    // See `enum fb_loop_setting` in `include/fb_settings.h`
    fb_play(&my_song, FB_LOOP_SETTING_LOOP);

    // Add `fb_update_vblank()` as VBlank ISR (ugba)
    IRQ_Init();
    IRQ_SetHandler(IRQ_VBLANK, fb_update_vblank);
    IRQ_Enable(IRQ_VBLANK);

    while (1)
        SWI_VBlankIntrWait();
}