1# An unpacker for *.PES files from The Playroom for MS-DOS by Broderbund (1989)
2
3import sys
4
5def pes_unpack(infile, outfile):
6
7    with open(infile, 'rb') as f:
8        data = f.read()
9
10    mode = data[4]
11    usz  = data[5] | (data[6] << 8) | (data[7] << 16)
12    ts   = data[8]
13
14    if mode != 2: raise Exception("Unknown compression method")
15    if ts & 0x80: raise Exception("Table w/flag not implemented")
16
17    h  = 0
18    tptr = 9 + ts
19    htabs = []
20
21    for i in range(ts):
22
23        nrec = data[9+i]
24        tbl = (h << 1, tuple(data[tptr : tptr+nrec])) 
25        htabs.append(tbl)
26        h = h * 2 + nrec
27        tptr += nrec
28        
29    out = []
30    bits  = 0
31    val   = 0
32
33    for i in ((n & (1<<x)) >> x  for n in data[tptr:] for x in (0,1,2,3,4,5,6,7)):
34
35        val = (val << 1) | i
36        ht = htabs[bits]
37        
38        if val >= ht[0] and val < ht[0] + len(ht[1]):
39
40            res = ht[1][val - ht[0]]
41            bits = 0
42            val  = 0
43            out.append(res)
44
45            if len(out) == usz:
46                break
47            
48            continue
49
50        bits += 1
51
52    with open(outfile, 'wb') as f:
53        f.write(bytes(out))
54
55if len(sys.argv) != 3:
56    print("Usage: python script.py <input.pes> <output.unpacked>")
57    sys.exit(1)
58
59input_file = sys.argv[1]
60output_file = sys.argv[2]

61
62pes_unpack(input_file, output_file)