Dump some stuff from a GameBoy Rom. Saves the Nintendo logo from it if PIL (or Pillow) is installed.

dump_yellow_gbc_info.py

import sys
import array


if len(sys.argv) < 2:
    filename = "pokeyellow.gbc"
else:
    filename = sys.argv[1]

rom = array.array('B')
rom.fromstring(open(filename, "rb").read())

logo = rom[0x104:0x134]
title = rom[0x134:0x143]

def byte_to_1bpp(n):
    return [
        (n & 0b10000000) >> 7,
        (n & 0b01000000) >> 6,
        (n & 0b00100000) >> 5,
        (n & 0b00010000) >> 4,
        (n & 0b00001000) >> 3,
        (n & 0b00000100) >> 2,
        (n & 0b00000010) >> 1,
        n &  0b00000001
    ]   

#print byte_to_1bpp(0xFF)
#print byte_to_1bpp(0x0F)
#print byte_to_1bpp(0xF0)

vmem = array.array('B', [
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,

    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
])

# Interesting Python GB emulator:  https://bitbucket.org/pypy/lang-gameboy/src/410e34ee2cffa503a4107439b6d4ab257f377095/pygirl/gameboy.py?at=default#cl-203

# GBC boot rom dissasemble: http://www.its.caltech.edu/~costis/cgb_hack/gbc_bios.txt

LINE_IN_BYTES = 6

sprite = 0
for n in xrange(0, len(logo), 24):
    for byte_i in xrange(n, n+24, 4):
        for i in xrange(0, 4):
            high_nibble = logo[byte_i+i] & 0b11110000
            low_nible = logo[byte_i+i] & 0b00001111
    
            if i < 2:
                offset = (i * LINE_IN_BYTES * 2) + sprite
                vmem[offset] &= high_nibble
                vmem[offset + LINE_IN_BYTES] &= low_nible << 4 # skip to the next line
            else:
                offset = ((i-2) * LINE_IN_BYTES * 2) + sprite
                vmem[offset] |= high_nibble >> 4
                vmem[offset + LINE_IN_BYTES] |= low_nible
        sprite += 1
    sprite = 24

try:
    from PIL import Image
    image = Image.frombytes('1', (48,8), vmem)
    image.save('logo.png')
except:
    pass

for line_start in xrange(0, len(logo), LINE_IN_BYTES):
    line_slice = vmem[line_start:line_start+LINE_IN_BYTES]

    line = sum([byte_to_1bpp(n) for n in line_slice], [])
    print ''.join([str(n) for n in line]).replace('0', ' ').replace('1', '#')

print "Title: %s" % title.tostring()