conv_skin.py

#!/usr/bin/python
from PIL import Image
import lzf
import struct

FILENAMES = ('gb_skin.png', 'gbc_skin.png')

def compress(data):
    return struct.pack('<H', len(data)) + lzf.compress(data)

outdata = b''
for name in FILENAMES:
    img = Image.open(name)

    palette = bytearray()
    pal = img.getpalette()
    for (r, g, b) in zip(pal[0:48:3], pal[1:48:3], pal[2:48:3]):
        color = ((g & 4) << 13) + ((b >> 3) << 10) + ((g >> 3) << 5) + (r >> 3)
        palette += struct.pack('<H', color)

    data = bytearray()
    last_pixel = None
    for pixel in (img.getpixel((x, y)) for y in range(img.height) for x in
                  range(img.width)):
        if last_pixel is None:
            last_pixel = pixel
        else:
            data.append(last_pixel * 16 + pixel)
            last_pixel = None

    if last_pixel is not None:
        data.append(last_pixel * 16)

    data = palette + compress(bytes(data))
    print(len(data))

    outdata += data

fout = open('skin.asm', 'w')
line = '.db '
comma = 0
for byte in outdata:
    to_append = ',' * comma + '$%02X' % byte
    if len(line + to_append) > 100:
        fout.write(line + '\n')
        line = '.db $%02X' % byte
    else:
        line += to_append
    comma = 1

if comma:
    fout.write(line + '\n')
fout.close()