07977624ae
TP5 is a 2012 Windows application supplied with the Guangzhou-Tongda LED
destination signs fitted to Yutong buses. It has no preview, so building a
destination list is guess-and-check, and it only runs on Windows.
The bus never talks to TP5 — the sign controller reads a .td5 file off an SD
card, and that is the whole interface. So this replaces the software without
touching any hardware or protocol: it just has to write byte-correct .td5.
Formats reverse-engineered from the sample files and TP5(En).exe, then verified
byte-for-byte:
.td5 the file the bus reads. Fixed-layout binary; each destination block
carries a CRC-16/ARC over block[3..len] and a rand() block id, which
together looked like one 4-byte field because RAND_MAX is 0x7fff.
.tp5 the editable project. Line-based text, UTF-16BE hex strings.
.font the sign's own bitmap fonts, each glyph row XORed with its char code.
The app is one self-contained HTML file: live LED preview at the real sign size
with real scrolling, spreadsheet/CSV import, multi-page destinations, undoable
delete, and export to both .td5 and .tp5.
Verified:
- rebuilds a real 46,080-byte TP5 export byte-for-byte with a recomputed CRC
- all 36 stored CRCs verify against the implementation
- driven through its own UI, re-exporting the real file differs in 7 bytes,
all of them the export timestamp
- running on a real bus: signs and driver's controller both correct
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
49 lines
1.3 KiB
Python
49 lines
1.3 KiB
Python
import struct
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from parse import records
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POLY = 0xA001
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def crc16(data, init=0, poly=POLY):
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c = init
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for b in data:
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c ^= b
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for _ in range(8):
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c = (c >> 1) ^ poly if c & 1 else c >> 1
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return c & 0xffff
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rs = records()
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for r in rs:
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r['chk'] = struct.unpack_from('<H', r['blk'], 1)[0]
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# candidate ranges (start, end) end=None means to end of block
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cands = []
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for s in [0,1,3,5,7,0xb,0xf,0x10,0x11,0x14,0x16,0x20,0x116,0x117]:
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cands.append((s, None))
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cands += [(0,3),(3,7),(0,0x116),(3,0x116),(7,0x116),(0x116,None)]
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blks = [r['blk'] for r in rs]
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chks = [r['chk'] for r in rs]
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best = []
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for (s,e) in cands:
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ok = 0
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for b,c in zip(blks,chks):
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seg = b[s:] if e is None else b[s:e]
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for init in (0, 0xffff):
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for xo in (0, 0xffff):
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pass
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if crc16(seg) == c: ok += 1
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if ok: print('range', hex(s), e, 'matches', ok, '/', len(rs))
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best.append((ok,s,e))
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best.sort(reverse=True)
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print('top:', best[:5])
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# also try with the crc bytes zeroed
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print('--- zeroed crc field ---')
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for (s,e) in cands:
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ok=0
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for b,c in zip(blks,chks):
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bb = bytearray(b); bb[1]=0; bb[2]=0
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seg = bytes(bb[s:] if e is None else bb[s:e])
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if crc16(seg) == c: ok+=1
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if ok: print('range', hex(s), e, 'matches', ok)
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