A simple Python utility to generate MLX listings

mlx.py

#!/usr/bin/python

# mlx.py - convert a .PRG program into an MLX listing.
# By default it uses the MLX 1 format (7 decimals per line), but
# the -2 option will use the MLX 2 format (9 hexadecimals per line).

import sys

def mlx1_encode(code, start_address):
    while len(code) % 6 != 0:
        code += "\x00"
    index = 0
    address = start_address
    while index < len(code):
        vals = [ord(c) for c in code[index:index+6]]
        vals.append((sum(vals) + address) % 256)
        print "%05d :%s" % (address, ",".join(["%03d" % i for i in vals]))
        index += 6
        address += 6


def mlx2_encode(code, start_address):
    while len(code) % 8 != 0:
        code += "\x00"
    index = 0
    address = start_address
    while index < len(code):
        vals = [ord(c) for c in code[index:index+8]]
        checksum = (address - 254 * int(address / 256)) % 255
        for v in vals:
            checksum = (checksum * 2 + v) % 255
        vals.append(checksum)
        print "%04X:%s" % (address, " ".join(["%02X" % i for i in vals]))
        index += 8
        address += 8


def mlx_prg(prg, mlx_version=1):
    if len(prg) < 3:
        print "Not a PRG file"
    start_address = ord(prg[0]) + 256*ord(prg[1])
    if start_address >= 2048 and start_address < 12288:
        startpage = (start_address + len(prg) + 254) / 256
        print "Before loading MLX to enter this program, enter this line:"
        print "POKE 44,%d:POKE %d,0:NEW" % (startpage, startpage*256)
        print
    print "Start address: %d" % start_address
    print "End address: %d" % (start_address + len(prg) - 3)
    print
    if mlx_version == 2:
        mlx2_encode(prg[2:], start_address)
    else:
        mlx1_encode(prg[2:], start_address)

if __name__=='__main__':
    mlx_version = 1
    target_file = None
    for arg in sys.argv[1:]:
        if arg == "-2":
            mlx_version = 2
        elif arg == "-1":
            mlx_version = 1
        else:
            target_file = arg
    if target_file == None:
        print "Usage: %s [-2] prgfile"
    else:
        mlx_prg(file(target_file, "rb").read(), mlx_version)