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Syphon_Filter_3/docs
Christopher Williams 2000cc4101 phase7: census duplicate bodies and expose a zero band of false positives
Matching conventions require a duplicate check before registering, because a
shared body is matched once and registered once per address. Phase 6 did that
check by hand and found one 12-byte pair. tools/sf3_dupes now hashes every
derived extent body and groups exact duplicates.

Results: 2284 extents, 65 multi-address groups, 2104 singletons. Only 10 groups
contain code (24 addresses, all exact-graded); 55 are all-zero bodies. The
hand-found pair 0x800262E0/0x800262EC is reproduced as g0002, which is the check
that the census measures what it claims. The largest real groups are 712 bytes
(0x8001084C/0x800189E8) and 436 bytes.

The zero groups are a real finding: 252 extents have all-zero bodies, 245 inside
the zero band 0x80147000..0x80170000. The cause is the inventory's jal grade,
which decodes every word as an instruction -- in a data region a word with
opcode 3 is graded as a call whose target lands in the zero band. The census
flags those groups rather than hiding them, and the worklist must exclude
degenerate bodies.

The census is tracked rather than ignored as the plan said, because it holds
addresses, sizes and grades only (the same class as the tracked inventory and
extents tables) and the worklist must be reproducible from tracked inputs. The
content hash is computed and never written.
2026-09-23 22:15:51 -04:00
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