xen32os/gen/fontgen.py

import json
import struct

# generates:
#   font_data.bin
#   font_table.bin
#   font_data.inc
#
# struct Char {
#   width: u8, height: u8, baseline: u8,
#   data_offset: offset into font_data
# } (7 bytes)

CODEPAGE = {
    0: None,
    128: 'Ξ',
    129: '\U0001f41d', # bee emoji
}
for x in range(32, 127):
    CODEPAGE[x] = chr(x)

BASELINE = 7

codepoints = json.load(open("ultlf/codepoints.json"))
font_data = json.load(open("ultlf/data.json"))
baselines = json.load(open("ultlf/trimmed_baselines.json"))

UNKNOWN = [
    "#  ###  #",
    "# #   # #",
    "#     # #",
    "#    #  #",
    "#   #   #",
    "#       #",
    "#   #   #",
]

SPACE = ["   "]

SCALE = 2
def scale(glyph):
    out = []
    for line in glyph:
        line_scaled = ""
        for ch in line:
            line_scaled += ch * SCALE
        out.extend([line_scaled] * SCALE)
    return out

with open("xenrom/data/font_table.dat", "wb") as table_file, open("xenrom/data/font_data.dat", "wb") as data_file, open("xenrom/data/font_data.inc", "w") as inc_file:
    table = b''
    data = b''

    for i in range(256):
        ch = CODEPAGE.get(i, None)
        unicode_codepoint = ord(ch) if ch is not None else None
        if unicode_codepoint is None:
            glyph = UNKNOWN
            baseline = 6
        elif unicode_codepoint == 32:
            glyph = SPACE
            baseline = 1
        else:
            ultlf_idx = codepoints.index(unicode_codepoint)
            glyph = font_data[ultlf_idx]
            baseline = baselines[ultlf_idx]

        if "X" in "".join(glyph):
            glyph = UNKNOWN
            baseline = 6

        glyph = scale(glyph)
        baseline *= SCALE

        table += struct.pack("<BBBI", len(glyph[0]), len(glyph), baseline, len(data))

        for line in glyph:
            for ch in line:
                data += b'\x00' if ch == ' ' else b'\x01'

    table_file.write(table)
    data_file.write(data)

    inc_file.write(f"const FONT_SIZE: {SCALE}\n")
    inc_file.write(f"const FONT_LINE_HEIGHT: {9 * SCALE}\n")