level_overlay was the least-characterised file in the level set -- no parser, no
located structure. It now has gc_formats::overlay and a real-disc test over all 27
levels:
overlay: 27 levels; field_00 1735808, field_08 1;
field_04 37540..=45308, field_0c 2763912..=3027336
(17 below the file length, 10 above);
+0x10..0x1220 identical on all
The header is four words. +0x0c is not the file length: it was recorded as one on
the strength of the first levels measured, where it sat near the file end, but
across all 27 it falls on both sides -- below on 17, above on 10 -- so it is an
ordinary level-specific word. The test asserts this, being the claim most worth
pinning.
The common prefix is 4 bytes, not the whole header: +0x00 is constant at 1735808
while +0x04 and +0x0c vary. Everything from +0x10 to +0x1220 -- 4624 bytes -- is
byte-identical on all 27 levels.
Still not named: what any of the four header words means, and how the
level-specific tail is structured. The module reports them as fields.
Also records in docs/plan/pcsx2-verification.md that the 64-byte RAM stride from
the previous commit is disproved. A 415 KB dump of level 1 finds the longest such
run at 27 records, not 384, and those are identity matrices -- 27 of them, one per
level. It is a per-level transform table, not the collision grid, and the 20.0
reported there was a coincidence.
ReaperOfVeriod
02ced5ee83