389 lines
15 KiB
Python
Executable File
389 lines
15 KiB
Python
Executable File
#!/usr/bin/env python3
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#(c) 2022 by 4am
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#license:MIT
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import wozardry # https://github.com/a2-4am/wozardry
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import bitarray # https://pypi.org/project/bitarray/
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import sys
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def myhex(b):
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return hex(b)[2:].rjust(2, "0").upper()
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class MoofTrack(wozardry.Track):
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def __init__(self, raw_bytes, raw_count):
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wozardry.Track.__init__(self, raw_bytes, raw_count)
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self.bit_index = 0
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self.revolutions = 0
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self.bits = bitarray.bitarray(endian="big")
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self.bits.frombytes(self.raw_bytes)
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while len(self.bits) > raw_count:
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self.bits.pop()
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def rewind(self, bit_count=1):
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self.bit_index -= bit_count
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while self.bit_index < 0:
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self.bit_index += self.raw_count
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self.revolutions -= 1
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def forward(self, bit_count=1):
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self.bit_index += bit_count
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while self.bit_index >= self.raw_count:
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self.bit_index -= self.raw_count
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self.revolutions += 1
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def bit(self):
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b = self.bits[self.bit_index]
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self.forward()
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yield b
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def nibble(self):
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while not next(self.bit()): pass
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n = 0b10000000
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for bit_index in range(6, -1, -1):
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b = next(self.bit())
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n |= b << bit_index
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yield n
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def find(self, sequence):
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starting_revolutions = self.revolutions
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seen = [0] * len(sequence)
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while (self.revolutions < starting_revolutions + 2):
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del seen[0]
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seen.append(next(self.nibble()))
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if tuple(seen) == tuple(sequence): return True
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return False
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def find_this_not_that(self, good, bad):
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starting_revolutions = self.revolutions
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good = tuple(good)
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bad = tuple(bad)
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seen_good = [0] * len(good)
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seen_bad = [0] * len(bad)
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while (self.revolutions < starting_revolutions + 2):
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del seen_good[0]
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del seen_bad[0]
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n = next(self.nibble())
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seen_good.append(n)
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seen_bad.append(n)
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if tuple(seen_bad) == bad: return False
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if tuple(seen_good) == good: return True
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return False
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class MoofAddressField:
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def __init__(self, valid, volume, track_id, sector_id):
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self.valid = valid
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self.volume = volume
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self.track_id = track_id
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self.sector_id = sector_id
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class MoofDataField:
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def __init__(self, valid, sector_id, tags, data):
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self.valid = valid
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self.sector_id = sector_id
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self.tags = tags
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self.data = data
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class MoofBlock:
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def __init__(self, address_field, data_field):
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self.address_field = address_field
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self.data_field = data_field
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class MoofRWTS:
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kDefaultAddressPrologue16 = (0xD5, 0xAA, 0x96)
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kDefaultAddressEpilogue16 = (0xDE, 0xAA)
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kDefaultDataPrologue16 = (0xD5, 0xAA, 0xAD)
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kDefaultDataEpilogue16 = (0xDE, 0xAA)
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kDefaultNibbleTranslationTable16 = {
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0x96: 0x00, 0x97: 0x01, 0x9A: 0x02, 0x9B: 0x03, 0x9D: 0x04, 0x9E: 0x05, 0x9F: 0x06, 0xA6: 0x07,
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0xA7: 0x08, 0xAB: 0x09, 0xAC: 0x0A, 0xAD: 0x0B, 0xAE: 0x0C, 0xAF: 0x0D, 0xB2: 0x0E, 0xB3: 0x0F,
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0xB4: 0x10, 0xB5: 0x11, 0xB6: 0x12, 0xB7: 0x13, 0xB9: 0x14, 0xBA: 0x15, 0xBB: 0x16, 0xBC: 0x17,
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0xBD: 0x18, 0xBE: 0x19, 0xBF: 0x1A, 0xCB: 0x1B, 0xCD: 0x1C, 0xCE: 0x1D, 0xCF: 0x1E, 0xD3: 0x1F,
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0xD6: 0x20, 0xD7: 0x21, 0xD9: 0x22, 0xDA: 0x23, 0xDB: 0x24, 0xDC: 0x25, 0xDD: 0x26, 0xDE: 0x27,
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0xDF: 0x28, 0xE5: 0x29, 0xE6: 0x2A, 0xE7: 0x2B, 0xE9: 0x2C, 0xEA: 0x2D, 0xEB: 0x2E, 0xEC: 0x2F,
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0xED: 0x30, 0xEE: 0x31, 0xEF: 0x32, 0xF2: 0x33, 0xF3: 0x34, 0xF4: 0x35, 0xF5: 0x36, 0xF6: 0x37,
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0xF7: 0x38, 0xF9: 0x39, 0xFA: 0x3A, 0xFB: 0x3B, 0xFC: 0x3C, 0xFD: 0x3D, 0xFE: 0x3E, 0xFF: 0x3F,
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}
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def __init__(self,
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address_prologue = kDefaultAddressPrologue16,
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address_epilogue = kDefaultAddressEpilogue16,
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data_prologue = kDefaultDataPrologue16,
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data_epilogue = kDefaultDataEpilogue16,
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nibble_translate_table = kDefaultNibbleTranslationTable16):
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self.address_prologue = address_prologue
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self.address_epilogue = address_epilogue
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self.data_prologue = data_prologue
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self.data_epilogue = data_epilogue
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self.nibble_translate_table = nibble_translate_table
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self.sectors_per_track = dict(zip(range(0xA0), (i for i in range(0x0C,0x07,-1) for j in range(0x20))))
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def _(self, track):
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return self.nibble_translate_table[next(track.nibble())]
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def find_address_prologue(self, track):
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return track.find(self.address_prologue)
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def address_field_at_point(self, track):
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h0 = self._(track)
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sector_id = self._(track)
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h2 = self._(track)
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volume = self._(track)
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checksum = self._(track)
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valid = h0 ^ sector_id ^ h2 ^ volume == checksum
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track_id = (h0 << 1) | ((h2 & 0b00000001) << 7) | ((h2 & 0b00100000) >> 5)
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return MoofAddressField(valid, volume, track_id, sector_id)
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def verify_nibbles_at_point(self, track, nibbles):
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found = []
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for i in nibbles:
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found.append(next(track.nibble()))
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return tuple(found) == tuple(nibbles)
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def verify_address_epilogue_at_point(self, track):
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return self.verify_nibbles_at_point(track, self.address_epilogue)
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def find_data_prologue(self, track):
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return track.find_this_not_that(self.data_prologue, self.address_prologue)
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def data_field_at_point(self, track):
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# three checksums
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c1 = c2 = c3 = 0
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# generator to decode grouped bytes while juggling three checksums
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def gcr_generator(byte_groups):
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nonlocal c1, c2, c3
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for d0, d1, d2 in byte_groups:
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c1 = (c1 & 0b11111111) << 1
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if c1 > 0xFF:
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c1 -= 0xFF
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c3 += 1
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b = d0 ^ c1
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c3 += b
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yield b
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if c3 > 0xFF:
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c3 &= 0b11111111
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c2 += 1
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b = d1 ^ c3
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c2 += b
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yield b
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if c2 > 0xFF:
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c2 &= 0b11111111
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c1 += 1
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b = d2 ^ c2
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c1 += b
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yield b
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# first nibble is sector number
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sector_id = self._(track)
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# read 700 nibbles, decode each against nibble translate table, store in 175 groups of 4
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nibble_groups = [(self._(track), self._(track), self._(track), self._(track))
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for i in range(175)]
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# convert each group of 4 nibbles into a group of 3 bytes to pass into the decoder
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gcr_byte = gcr_generator((((n[1] & 0b00111111) | ((n[0] << 2) & 0b11000000),
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(n[2] & 0b00111111) | ((n[0] << 4) & 0b11000000),
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(n[3] & 0b00111111) | ((n[0] << 6) & 0b11000000))
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for n in nibble_groups))
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# decode 524 bytes (12 tag bytes + 512 data bytes)
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tags = [next(gcr_byte) for i in range(12)]
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data = [next(gcr_byte) for i in range(512)]
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# validate checksums against last data field nibble and three epilogue nibbles
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valid = nibble_groups[-1][-1] == ((c1 & 0b11000000) >> 6) | ((c2 & 0b11000000) >> 4) | ((c3 & 0b11000000) >> 2)
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valid &= self._(track) == (c3 & 0b00111111)
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valid &= self._(track) == (c2 & 0b00111111)
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valid &= self._(track) == (c1 & 0b00111111)
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return MoofDataField(valid, sector_id, tags, data)
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def verify_data_epilogue_at_point(self, track):
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return self.verify_nibbles_at_point(track, self.data_epilogue)
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class DefaultLogger:
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def warn(self, message, T=None, S=None, X=None, Y=None):
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if T: T = myhex(T)
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if S: S = myhex(S)
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message = message.format(**locals())
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sys.stderr.write(message)
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sys.stderr.write('\n')
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info=warn
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error=warn
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class MoofDiskImage(wozardry.WozDiskImage):
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kE7Bytestream = (0x2B, 0x00, 0x2B, 0xFD, 0x83, 0x6F, 0x20, 0xE2,
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0x8D, 0x99, 0x49, 0x44, 0x47, 0x82, 0xD9, 0x26,
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0xFB, 0xC6, 0x3, 0xF8)
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kPACEPrologue = (0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
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0xFF, 0xFF, 0xFF, 0xFF, 0xAB, 0xCD, 0xEF, 0xEF)
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def __init__(self, iostream=None, rwtsclass=MoofRWTS, loggerclass=DefaultLogger):
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wozardry.WozDiskImage.__init__(self, iostream)
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self.logger = loggerclass()
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self.rwts = rwtsclass()
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for i,t in zip(range(len(self.tracks)), self.tracks):
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self.tracks[i] = MoofTrack(t.raw_bytes, t.raw_count)
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self.parse()
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def get_pace_key_at_point(self, track, bit_index):
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# save bitstream position
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track.bit_index, bit_index = bit_index, track.bit_index
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key = []
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if self.rwts.verify_nibbles_at_point(track, self.kPACEPrologue):
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for i in range(4):
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next(track.nibble())
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for i in range(4):
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x = (next(track.nibble()) << 8) + next(track.nibble())
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x = x & 0x5555
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x = (x | (x >> 1)) & 0x3333
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x = (x | (x >> 2)) & 0x0f0f
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x = (x | (x >> 4)) & 0x00ff
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x = (x | (x >> 8)) & 0xffff
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key.append(x)
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key.reverse()
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# restore bitstream position
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track.bit_index, bit_index = bit_index, track.bit_index
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return "".join(map(myhex, key))
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def parse(self):
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self.blocks = []
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# only 400K and 800K disks supported at the moment
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if not self.info["disk_type"] in (1,2): return
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for track_index in self.tmap:
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if track_index == 0xFF: continue
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track = self.tracks[track_index]
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seen_sectors = []
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track_id = -1
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while self.rwts.find_address_prologue(track):
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address_field = self.rwts.address_field_at_point(track)
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# log if address field checksum doesn't match
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if not address_field.valid:
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self.logger.warn(
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'T{T},S{S} Address field checksum invalid',
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T=address_field.track_id,
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S=address_field.sector_id
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)
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continue
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# log if track ID is ridiculous
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if not (0x00 <= address_field.track_id <= 0x9F):
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self.logger.warn(
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'Address field track ID {T} invalid',
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T=address_field.track_id
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)
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continue
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# log if sector ID is ridiculous
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if not (0x00 <= address_field.sector_id < self.rwts.sectors_per_track[address_field.track_id]):
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self.logger.warn(
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'Address field sector ID {S} invalid',
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S=address_field.sector_id
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)
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continue
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# log if address field epilogue isn't next
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if not self.rwts.verify_address_epilogue_at_point(track):
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self.logger.warn(
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'T{T},S{S} Address field epilogue invalid',
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T=address_field.track_id,
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S=address_field.sector_id
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)
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continue
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# if we see duplicate sector IDs, assume we're done
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if address_field.sector_id in seen_sectors: break
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seen_sectors.append(address_field.sector_id)
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old_bit_index = track.bit_index
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if not self.rwts.find_data_prologue(track):
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# if we didn't find any data field prologue at all
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# before the next address field prologue, then check
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# if this is a specially formatted protection sector
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# from which we can extract some useful information
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decryption_key = self.get_pace_key_at_point(track, old_bit_index)
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if decryption_key:
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self.logger.info(
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'T{T},S{S} Found PACE protection, key={X}',
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T=address_field.track_id,
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S=address_field.sector_id,
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X=decryption_key
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)
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continue
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try:
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data_field = self.rwts.data_field_at_point(track)
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except KeyError:
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# log if GCR decoding failed
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self.logger.warn(
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'T{T},S{S} Data field contains invalid nibble',
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T=address_field.track_id,
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S=address_field.sector_id
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)
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continue
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# log if checksums didn't match after GCR decoding
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if not data_field.valid:
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self.logger.warn(
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'T{T},S{S} Data field checksums invalid',
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T=address_field.track_id,
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S=address_field.sector_id
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)
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continue
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# address and data fields are supposed to contain
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# matching sector IDs, so log if they don't match
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if address_field.sector_id != data_field.sector_id:
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self.logger.warn(
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'T{T},S{S} Address and data field sector IDs do not match',
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T=address_field.track_id,
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S=address_field.sector_id
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)
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continue
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# log if sector data contains E7 bitstream
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if (sum(data_field.data[:0x18E]) == 0) and (tuple(data_field.data[0x18F:0x1A3]) == self.kE7Bytestream):
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#print(data_field.data[0x18F:0x1A3])
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self.logger.warn(
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'T{T},S{S} Found E7 bitstream',
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T=address_field.track_id,
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S=address_field.sector_id
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)
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# log if data field epilogue isn't next
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if not self.rwts.verify_data_epilogue_at_point(track):
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self.logger.warn(
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'T{T},S{S} Data field epilogue invalid',
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T=address_field.track_id,
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S=address_field.sector_id
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)
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continue
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track_id = address_field.track_id
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self.blocks.append(MoofBlock(address_field, data_field))
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# move on if we didn't find any valid sectors
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if track_id == -1: continue
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# log if we didn't find enough sectors
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sector_count = len(seen_sectors)
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expected_count = self.rwts.sectors_per_track[track_id]
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if sector_count < expected_count:
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self.logger.warn(
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'T{T} Found {X} sectors (expected {Y})',
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T=track_id,
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X=sector_count,
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Y=expected_count
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)
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def driver(filename):
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with open(filename, 'rb') as f:
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mdisk = MoofDiskImage(f)
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if __name__ == '__main__':
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driver(sys.argv[1])
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