MOTHER2 flyover (12x12px) font extraction script

font_test.py

#!/usr/bin/env python3
# font experiment

NUM_GLYPHS = 313
GLYPH_SIZE_BYTE = 18
GLYPH_HEIGHT = 12
GLYPH_WIDTH = 12

PIXEL0 = '⬜'
PIXEL1 = '⬛'

with open(r"../Mother 2 - Gyiyg no Gyakushuu (Japan).sfc", 'rb') as f:
    f.seek(0x210000)
    fontdata = f.read(NUM_GLYPHS * GLYPH_SIZE_BYTE)

def getGlyphData(i: int) -> bytes:
    return fontdata[i * GLYPH_SIZE_BYTE : (i+1) * GLYPH_SIZE_BYTE]

def outputBits(gfxData12Bits: int):
    for _ in range(GLYPH_WIDTH):
        char = PIXEL1 if gfxData12Bits & 0x800 else PIXEL0
        print(char, end='')
        gfxData12Bits <<= 1
    print()

def renderGlyph(data: bytes):
    for j in range(GLYPH_HEIGHT // 2):
        # Every 3 bytes (8 * 3 = 24 bits) stores 2 rows of graphics data (12 * 2 = 24 bits)
        # If we use ABCDEFGHIJKL for the top row, and a-l for the bottom row, the format is:
        # Byte 0: ABCDEFGH
        # Byte 1: IJKLabcd
        # Byte 2: efghijkl
        rowsData = data[j * 3 : (j + 1) * 3]
        rowsInt = int.from_bytes(rowsData, 'big')
        outputBits(rowsInt >> 12)
        outputBits(rowsInt)

for i in range(NUM_GLYPHS):
    renderGlyph(getGlyphData(i))
    print('==' * GLYPH_WIDTH)