GameBoy Advance Bitmap Image Converter
written by Sayuri L. Kitsune (2010)

Software is licenced under the GNU General Public Licence (GPL)
http://www.gnu.org/licenses/gpl-3.0.txt

INTRODUCTION:

The gbabmp tool will take Windows Bitmap Files (.bmp) that are either
24-bit or 8-bit in color depth and convert them into .gbm files.
The .gbm files are ready to be copied into the VRAM of the GameBoy Advance.

The .bmp images must have dimensions that are multiples of 8.
(ex: 8, 16, 24, 32, 40, 48, ...)

Most GBA games use images that are either 256-color or 16-color.

USAGE:

gbabmp [image].bmp
This will convert the image to either a 16-bit full color image or an 8-bit
256-color image.

gbabmp -c4 [image].bmp
This works only on 8-bit color images with only the first 16 colors used.
This converts the image into a 16-color image.

gbabmp -rXXX -gXXX -bXXX [image].bmp
The values for r, g, and b define the transparent color. The output image
will have that color first in its color palette. This only works on 8-bit
color images.