tapgenerator_overlander.py

import struct, sys

p = ("\x2f\x43", "\x43\x2f")
pnewdata = "\x57\x43"
penddata = "\x57\x2f"


def add_kernel_byte(c):
    s = pnewdata
    c = ord(c)
    csum = 1
    
    for i in xrange(8):
        bit = (c >> i) & 1
        s += p[bit]
        csum ^= bit
            
    s += p[csum]
    
    return s
            
def add_loader_byte(c):
    s = ""
    c = ord(c)
    
    for i in xrange(8):
        bit = (c >> i) & 1
        s += "\x27\x45"[bit]
    
    return s
    
def add_kernel_block(data, headersize, pausesize):
    s = "\x00" + struct.pack("<I", pausesize)[0:3]
    
    s += "\x2f" * headersize

    for c in data:
        s += add_kernel_byte(c)
        
    s += penddata
    s += "\x2f" * 0x300

    for c in data.replace("\x89\x88\x87\x86\x85\x84\x83\x82\x81", "\x09\x08\x07\x06\x05\x04\x03\x02\x01"):
        s += add_kernel_byte(c)

    s += penddata
    
    return s
    
def add_loader_block(data, pausesize):
    s = "\x00" + struct.pack("<I", pausesize)[0:3]

    s += "\x27"
    
    for i in xrange(64):
        s += add_loader_byte("\x01")
    
    for c in data:
        s += add_loader_byte(c)
        
    return s

f = open("P0000152.A44", "rb")

f.read(512)

tapdata = ""

while True:
    header = f.read(10)
    if len(header) == 0:
        break
        
    dunno1, dunno2, dunno3, sz, dunno4 = struct.unpack(">HHHHH", header)
    
    print "%x %x %x %x %x" % (dunno1, dunno2, dunno3, sz, dunno4)
    if sz < 10:
        print "TOO SMALL"
        break
        
    data = f.read(sz - 10)
    
    if dunno4 == 0xff00:
        pausesize = 150000 * dunno1
        tapdata += add_kernel_block(data, dunno3, pausesize)
    elif dunno4 == 0x1c00:
        pausesize = 5000 * dunno1
        tapdata += add_loader_block(data, pausesize)
    else:
        print "UNKNOWN LOADER", hex(dunno4)
        exit()
        

tapdata += "\x00" + struct.pack("<I", 150000 * 0x10)[0:3]

of = open("output.tap", "wb")
of.write("C64-TAPE-RAW\x01\x00\x00\x00" + struct.pack("<I", len(tapdata)) + tapdata)
of.close()