import struct

knowntids = open('knowntitleids.txt', 'rb').readlines()
knowntids = [x.rstrip() for x in knowntids] #Remove line breaks

i = 0
with open('nand.fat16.bin', 'rb') as fh:
    while 1:
        data = fh.read(4*1024)

        x = data.find('NCCH')
        if x != -1:
            foundpos = x + (i*4*1024)
            #print 'Found NCCH at: ' + str(foundpos)
            savedpos = fh.tell()

            fh.seek(foundpos + 0x18)
            titleid = fh.read(8)
            titleid = ''.join('%02X' % ord(x) for x in titleid[::-1])
            if titleid[:4] == b'0004':
                if not titleid in knowntids:
                    print titleid
                    fh.seek(foundpos + 4)
                    size = struct.unpack('<I', fh.read(4))[0] * 512
                    if size < (128*1024*1024):
                        fh.seek(foundpos - 0x100)
                        with open(titleid + '.ncch', 'wb') as title:
                            title.write(fh.read(size))

            fh.seek(savedpos)
        i += 1

        if len(data) < (4*1024):
            break