GBA link cable logic analyzer decoder

gbalink-decoder.py

import csv
input_file = 'rme4bcg.csv'
output_file = 'rme4bcg-decoded.csv'
with open(input_file) as c:
    with open(output_file, 'w') as c2:
        c.readline()
        log = csv.reader(c)
        out = csv.writer(c2)
        out.writerow(['timestamp', 'player', 'current_word'])
        active = False
        start = 0
        bit = True
        current_word_bits = 0
        current_word = 0
        old_bit = True
        player = 0
        for line in log:
            new_active = not int(line[1])
            new_time = float(line[0])
            bit = bool(int(line[2]))
            if new_active and not active:
                current_word = 0
                current_word_bits = -2
                new_active = bit
                player = 0
            if active:
                assert current_word_bits <= 16
                if current_word_bits == -2:
                    if not bit:
                        current_word_bits = -1
                elif current_word_bits < 16:
                    bits = int((new_time - start) * 118000)
                    if current_word_bits + bits >= 16:
                        bits = 16 - current_word_bits
                    if old_bit and current_word_bits + bits > 0:
                        current_word |= ((1 << bits) - 1) << max(current_word_bits, 0)
                    current_word_bits += bits
            if current_word_bits == 16:
                if not bit or not new_active:
                    #print(player, '0x%04X (%.6f)' % (current_word, new_time))
                    out.writerow([new_time, player, '0x%04X' % current_word])
                if not bit:
                    current_word = 0
                    current_word_bits = -1
                    player += 1
            start = new_time
            active = new_active
            old_bit = bit