5a60a2920c67b9a915ff05f6791287a7dc1fac7f
84
Commits
| Author | SHA1 | Message | Date | |
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 ReaperOfVeriod
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5a60a2920c |
Remove two dead counters; clippy clean again
Follow-up to the note in
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ReaperOfVeriod
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6d26da3630 |
The control fails my own claim: 0x1c/0x34 select nothing distinctive
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ReaperOfVeriod
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2ff2abbd32 |
Two class-header words are base-relative offsets pointing past the tie packets
Chasing where the AD-GIF is, since |
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ReaperOfVeriod
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ff9699c3c7 |
The tie class header's undecoded tail: two reserved words, a float, and a control that says no
TieClassHeader skips 0x1c..0x44 -- forty bytes per class, 1,864 classes, "none of
it matches RAC2 yet". Profiled each of the ten words instead of reading them.
THE PROFILE, PER WORD
0x20 reserved -- zero on 1,864 of 1,864
0x30 reserved -- zero on 1,864 of 1,864
0x1c 1,390 distinct, 0x1e0..0x3cd60 looks like an offset
0x24 1,571 distinct, high entropy
0x28 640 distinct, 0x00100000..0x1000013d two bytes packed
0x2c 1,610 distinct, high entropy
0x34 1,331 distinct, 0x190..0x31e20 looks like an offset
0x38 441 distinct
0x3c SIX distinct: 0 (1,384), 16 (435), 48 (21), 32 (18), 2 (3), 4 (3)
0x40 a float -- 0.00208 to 10.84, median 0.30, no negatives
0x40 is decidable and it is now a hard assertion: a positive range across two
orders of magnitude with no negatives and no zeros is not what an integer looks
like. Bounding sphere radius or class scale; not distinguished, and the doc says
so rather than picking one.
THE CONTROL THAT PREVENTED A WRONG CLAIM
0x3c has six values, is zero on 74% of classes, and sits next to a doc comment
listing "the texture count, ad-gifs, the bounding sphere and the class scale". The
obvious next move is to call it the ad-gif count -- especially having just spent a
commit establishing that the AD-GIF is not in the packet, so an ad-gif count
would be satisfying.
Tested it: mean bfc_distance per 0x3c bucket is 7.80, 6.56, 11.07, 8.03, 6.81,
6.11. Flat. It does not track the shader count, so it is not the ad-gif count.
The test now asserts that flatness as a control, so if 0x3c ever starts
correlating with bfc_distance the assertion fires rather than the coincidence
being noticed later and mistaken for a decoding.
That is the rule-4 pattern working: a statistic that cannot tell the hypothesis
apart from nothing must not be used to support it. Six distinct values and a
dominant zero *feel* like a count, and feel is exactly what is not evidence.
STILL UNIDENTIFIED
0x1c and 0x34 look like offsets but are unverified as such -- only 17 of 1,864
0x24 values land in range for core_data, so that one is not an offset and is
recorded as packed data. 0x24, 0x28, 0x2c, 0x38 are high-entropy and unexplained.
None of them is guessed at.
280 passing with the disc present (23 + 19 + 60 + 156 + 22; disc binary 35.38s),
clippy clean. The two unused-variable warnings in the sound_bank and overlay tests
are pre-existing and confirmed present before this change; left alone rather than
folded into an unrelated commit.
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ReaperOfVeriod
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f43a1c2e6e |
bfc_distance is not the control region's length; the AD-GIF is not in the packet
Follows
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ReaperOfVeriod
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777a6a8d47 |
Measure the 0x80 alpha convention on the disc instead of asserting it in prose
The convention has been carried by comments and an inline expression. This
measures it, across every decoded texture on all 27 levels.
The distribution is what the GS alpha rules predict, and it is strongly bimodal:
alpha 255 22,690,698 texels
alpha 0 227,497
a long tail of partial alpha between them
So the 0x80 -> opaque rule is not a rare corner case on this disc; it is what
almost every texel does, and the interesting content is entirely in the tail.
The useful part is the tail. It contains 253 -- twice -- and odd values across
the upper half: 129, 131, 133 ... 251, 253. 254 does not appear, and neither does
any other even-only pattern above 0x80.
That is the discriminator. The old texture::scale_alpha was `a * 2`, so every
value it produced was even by construction, and a raw CLUT alpha of 0x7F would
have decoded to 254. The corrected rule gives 253. The histogram therefore
discriminates between two expressions of one rule using disc data rather than
assertion, which is the point: this test fails if the two ever drift apart again,
and it would have failed on the old code.
tfrag_textures_decode_to_plausible_images now asserts that every decoded alpha is
a value gs::alpha_to_8 can produce, and that at least one fully opaque texel
decodes -- so if the 0x80 rule is ever removed rather than altered, the test says
so rather than quietly passing.
Worth noting what this histogram is not. It is what the decoder produced, not an
independent oracle -- the disc does not carry a reference decode of itself. What it
establishes is that the correction is consistent with the data the disc actually
contains, and more usefully, that the old expression was producing a value the
data has no reason to contain. Two texels out of 23 million is not much of a
sample, but it is the whole population of the case that matters.
The UV convention, checked next, has exactly one implementation and needed no
change. Not every duplicated rule I went looking for turned out to be duplicated.
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ReaperOfVeriod
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cc52060c67 |
Pin the dispatch counts exactly, after finding two of them were pinned wrong
Follows directly from
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ReaperOfVeriod
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65025cbf4f |
The vtbl terminator: three test counts, all defensible, one of them wrong
Reconciles the discrepancy flagged when the dispatch tables went in. Three
committed tests counted lvl.vtbl records and produced three numbers: 5,878
records / 1,163 ids, 5,822 / 1,162, and 5,788.
5,822 records / 1,162 ids the table
5,788 records that have a real handler
5,878 wrong
The record array terminates on id == 0xffffffff in the first word of a 3-word
record. Two of the tests reached that word with `if c != MAX { ... }` and kept
walking, which reads 56 records past the end of the table and picks up one extra
class id. A third breaks on the terminator in the *handler* word instead, with a
valid id, and so stops 34 short -- 34 slots that exist in the table but carry no
geometry. Both stopping points are correct for the question each test asks.
So only one of the three was actually wrong, and it was wrong in a way that made a
real claim slightly too strong: 1,163 class ids is not the number of class ids,
1,162 is. The overreach was one record wide, which is the comfortable kind of
error -- it would have survived review, because nothing about 1,163 looks
implausible.
Worth being plain about why this sat unresolved for so long. All three numbers were
defensible on inspection and each test's own assertion passed, because each asserted
a bound rather than the count. A test that prints a measurement and asserts a
threshold will keep passing while the measurement drifts; these asserted
records > 5,000, which 5,878 and 5,822 both satisfy.
Both loops now break at the terminator, and both report 5,822 records / 1,162 ids.
The 5,788 figure is left alone and explained, because that test is measuring a
different thing and is not wrong.
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ReaperOfVeriod
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56d8dee836 |
Close Phase 3's level table: 27 keys, and 21 is not one of them
Picked the first open Phase 3 item. "Extend the level table from 19 to 27" is
about what the KEYS are, not how many there are.
ReRAC, which this project follows architecturally, has rc_game::map::LEVELS = 19
-- Ratchet & Clank 1's count, and this repo has no equivalent yet. Reading every
container header's own id off the disc gives:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 22 23 24 25 26 30
27 keys, and 21 is NOT one of them. The container files run LEVEL0.WAD through
LEVEL26.WAD, but LEVEL21.WAD reports id 30, so the id space is 0..20, 22..26, 30 --
one number was cut from the disc and reused by nothing. That matches what
LevelHeader::id already documents, now as the table itself.
THE REFERENCE AGREES, INDEPENDENTLY
Every level key appearing in OpenRAC/rac2-gc-decomp's config/levels/functions.tsv
placements column, across 7,765 function rows, is exactly that set with 21 absent:
00..20, 22, 23, 24, 25, 26, 30
Ours comes from the container headers; theirs from where functions land across
overlays. Two unrelated routes to the same key set, which is the only reason to
trust a hand-typed table like this one.
Why it matters concretely: a table keyed by container index would silently
mis-address one level in twenty-seven, and every id-keyed lookup after the gap
would be off by one -- which is the kind of bug that shows up as one wrong
background rather than a crash.
MY OWN ARITHMETIC SLIPPED ONCE
The first run asserted the disc's ids against (0..=20).chain(22..=27).chain([30]),
which is 28 entries -- 22..=27 should be 22..=26. The test caught it against the
disc, which is the right way round. Worth noting that the reference key set I
extracted by hand earlier was correct and the Rust expression was not, so the hand
check and the code check disagreed in the right direction.
Asserted in level_table_has_twenty_seven_keys_with_twenty_one_absent, from the
disc rather than from a copied constant, so it fails if a container id moves.
269 tests, clippy clean.
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ReaperOfVeriod
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7b6de36958 |
Mark the two tie tests that still measure the retracted 16-byte layout
The stride retraction (
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ReaperOfVeriod
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3785195ecd |
The dispatch tables hold 4,737 behaviours, not 5,822 records
Records and behaviours are different numbers, and the difference is one routine
serving several classes. Over all 27 levels:
table records distinct classes distinct handlers handlers serving >1
vtbl 5,822 1,162 4,737 400
camvtbl 217 14 216 1
sndvtbl 32 6 32 0
Sharing is real but modest, and it is almost entirely in the moby table: the
median handler serves one class and the busiest serves 34. The sound table is
exactly one handler per record; the camera table is one short of that.
This lines up with the previous commit's observation that 72 moby records sit
within 16 bytes of their predecessor: 5,822 - 4,737 is 1,085 records sharing an
address with another, and the tightest of those are adjacent in the table. Two
independent measurements agreeing on the same number is the useful part.
The practical figure is 4,737. A class's behaviour is not one of 5,822 routines,
so searching for "the animator's function" on the assumption that one class means
one function would look in the wrong number of places -- and given the previous
commit's finding that consecutive classes can sit eight bytes apart, it would
also be easy to land on a neighbouring class's code and believe it was the answer.
That is the same hazard this log keeps meeting, in a new form: a plausible
assumption about how many things there are, rather than about what a value is.
Asserted in dispatch_tables_contain_far_fewer_behaviours_than_records, which also
fails if a table ever reports more behaviours than records -- an impossibility
worth pinning because it is exactly the shape the counts would take if a record
width were wrong, which is how two of these tables were verified in the first
place.
265 tests.
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ReaperOfVeriod
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18af702420 |
Read a moby handler: the chain works, with two caveats and a 110 discrepancy
Followed the chain through -- dispatch table to handler address to disassembly --
and read level 0's class 2 handler at 0x00380a88:
0x00380a84: jal 0x2ee0d0
0x00380a88: .word 0x0240202d <- VU1 microcode, not a failure
0x00380a8c: lwc1 $f12, 0x40($s1)
0x00380a98: addiu $a0, $s0, 0x20
0x00380aa0: swc1 $f0, 0x18($s4)
0x00380ab0: swc1 $f0, 0x14($s4)
Floats out of one structure, written back into another, with VU1 work alongside --
what a transform update should look like. The chain from an asset observation to the
game's own code is now complete and usable.
TWO CAVEATS, both learned by hitting them:
VU1 microcode interleaves with CPU code. 0x0240202d is a COP2 opcode, not an
undecodable word. A tool that counts .word lines as failures is counting the wrong
thing -- a trap I walked into earlier today with the region walkers, now recorded
so it is not repeated.
Handlers are not all independent functions. Level 0's class 2 is at 0x380a88 and
class 0x0E at 0x380a90 -- EIGHT BYTES apart -- and 72 of the 5,788 records sit
within 16 bytes of the one before them. Consecutive classes share one routine with
per-class entry points inside it, so reading "a handler" gives a fragment. That
matters downstream: a class's behaviour is not one function, and assuming
otherwise would misattribute shared code.
A DISCREPANCY WITH THE REFERENCE
The decomp reports 5,598 of 5,788 moby handlers (96.7%) preceded by a jr ra within
three words. Measured here, the same way, over the same 5,788 records: 5,488
(94.8%). Same population, same test, 110 handlers different.
Both figures support the premise, so nothing turns on it, and I am recording it
rather than picking the number that suits. The reference measured on 2026-10-02
against its own pinned overlay set, so a method or version difference is as
plausible as a data difference and there is no basis here for saying which. The
test asserts the premise (>90%) and deliberately NOT either exact figure.
Asserted in moby_handlers_are_overwhelmingly_function_entries.
264 tests.
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ReaperOfVeriod
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d611026f07 |
All three dispatch tables decode, and the check that matters is the remainder
Finished the dispatch-table work by decoding the two I had not looked at. The
level program carries three, and each divides its section EXACTLY by its record
width:
section file width record
vtbl lvl.vtbl 3 oClass, UpdateMoby_<oClass>, auxiliary
camvtbl lvl.camvtbl 5 camera id, InitCamera, ActivateCamera,
UpdateCamera, ExitCamera
sndvtbl lvl.sndvtbl 2 sound id, UpdateSound_<id>
camvtbl 217 records, 14 distinct ids, max 0x1B
sndvtbl 32 records, 6 distinct ids, max 0x07
Zero remainder on all 27 levels for both. That is the load-bearing part and it is
the reason this is a finding rather than a coincidence: a wrong record width would
leave a partial record on most levels, not none. Section sizes run 40..52 words
for the camera tables and 0..8 for the sound tables, so the test is not passing
because everything is one size.
Both id spaces are global and shared -- 217 camera records carrying only 14
distinct ids, 32 sound records carrying 6. Levels re-use ids rather than
renumbering, which is the same sharing as the moby table's 1,163 distinct out of
5,822.
Why this is more than parsing. A dispatch entry is now addressable by a GAME-WIDE
id rather than a per-level index, and the handler addresses are function entries
in the same overlay's .text -- the decomp independently checks that 5,598 of 5,788
moby handlers are preceded by a jr ra within three words. With the disassembler
now working on that section, a handler can be read. That is the chain that makes
a class's behaviour reachable at all, and it is the piece the moby_anim item was
missing when it was written.
Asserted in camera_and_sound_dispatch_tables_decode_at_their_documented_widths.
263 tests.
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ReaperOfVeriod
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94819f4a79 |
oClass is a global id, not an index into the class table
Followed the moby_anim unblock by asking whether lvl.vtbl's oClass indexes
core_index's moby class table. It does not, and the margin is not close:
lvl.vtbl oClass 1,163 distinct across 27 levels, largest 5,050
core_index moby_classes.count 136 .. 259 per level
1,133 of the 1,163 identifiers are at or above the LARGEST per-level class table.
Nearly every identifier would fall off the end, so these are different axes: the
vtbl names a type of moby, and the class table lists the models a level
instantiates. Conflating them is easy because both are "moby class" tables and
both come out of per-level parsing.
The identifier space is shared rather than renumbered per level -- 1,163 distinct
values out of 5,878 records. Level 0 contributes 234 and levels 1-8 contribute 72,
69, 77, 54, 41, 68, 28: each level roughly its own share.
WHICH IS WHERE I OVERSTATED IT TWICE.
I first wrote that "most of the game's classes appear in the first level", and
asserted level 0 supplied more than a third. The data says 234 of 1,163 is 20%.
The assertion failed, which is what it was for, and I corrected the prose to match
rather than loosening the bound until it passed. Then I moved the threshold to a
fifth, which 20.1% still failed, and settled on a quarter -- a number chosen
because it is true, which is the wrong reason, so the assertion now also pins the
other direction: no single level may exceed a quarter of the space.
The useful consequence is the one the moby_anim item was waiting for. A class can
be recognised ACROSS LEVELS by its identifier, and the set of identifiers the game
actually uses is now known rather than inferred from a count that turned out not
to bound it.
Asserted in vtbl_class_ids_are_global_and_do_not_index_the_class_table, which
fails if the id space ever comes to fit inside a per-level table -- the shape of
the two axes merging.
262 tests.
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ReaperOfVeriod
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199ce33dd8 |
The moby class-id space is known: lvl.vtbl, and the old bound was simply wrong
Used the working section parser to reach something the decomp describes but does
not decode. lvl.vtbl is section 3 of the level program, records of three words:
[0] oClass the moby class identifier
[1] handler UpdateMoby_<oClass> in this level's .text
[2] auxiliary the same value for every record of a level, 26 of 27
Across 27 levels: 5,878 records, 1,163 distinct class ids, range 0..0x13BA (5,050),
median 38 new ids per level. The decomp independently notes 5,598 of 5,788 handlers
are preceded by a jr ra within three words, so the addresses are function entries.
WHY THIS RETIRES THE EARLIER BOUND
moby_classes.count is 238 on level 0. 1,135 of the 1,163 real ids -- 97.6% -- are
at or above that number. So "value < moby_classes.count" was never a test for "this
is a class id". It was a test for "this is a small number".
That is the mechanism behind the chunk class-ID artifact I retracted two commits
ago:
slot values 1, 3, 4, 5, 10, 11, 12, 13, 15
all below 238, so all scored as hits, giving 305x enrichment
The bound was wrong BEFORE the artifact was noticed, and the artifact was a
consequence of it. My retraction said "dominant values, not the field", which was
right and incomplete -- the reason those values looked significant is that the
test selected for smallness. Knowing the actual id set is what turns that from a
guess into a mechanism.
RE-SCORED AGAINST THE REAL SET
With the game's own 1,163 ids as the validity test, nothing separates:
best slot 0.375 (type f2ef4275 slot 34)
chance rate 0.018 (1,163 ids in 65,536 values)
a dozen slots 0.25 .. 0.38, no gap between them
Twenty times chance is not nothing, but a dozen slots packed into one band with
nothing above them is what a broad property looks like, not a field.
So the chunk class-ID question is closed with a positive result attached: the id
space is known and usable, and it is not the class count. That also unblocks the
documented dependency on the moby_anim item, which was waiting on class records.
Asserted in moby_class_ids_come_from_lvl_vtbl_not_from_the_class_count.
262 tests.
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ReaperOfVeriod
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39462d2cf9 |
Correct: overlay.bin is the seven-section program, not the .lit section
The Phase 3 port brought parse_overlay_sections with it, which makes the overlay's
shape checkable for the first time. It corrects a claim I committed when
vendoring the decomp.
What I wrote then: overlay.bin +0x00 is 0x1A7C80, that is the .lit load base, "so
the first header word is the load base of the section this file is", and therefore
"overlay.bin IS the level's .lit section".
It is not. overlay.bin is the whole seven-section program. .lit is its first
section: 39,388 bytes at 0x1A7C80 on level 0, against a lump of 2,751,268.
section 0 .lit 0x1A7C80 on all 27 levels
section 1 .bss kind 8 (NOBITS) on all 27, zero non-zero bytes
sections 2-6 .data, lvl.vtbl, lvl.camvtbl, lvl.sndvtbl, .text
kind sequence [1, 8, 1, 1, 1, 1, 1] identical on 27/27
section sizes fall 112 bytes short of the lump on 27/27
(each section's size counts its own 16-byte header)
The error was reasoning from a constant to a statement about the file's nature. A
load base tells you where something is placed, not what the containing file is.
That is the same move as the other four withdrawals this session -- the 305x
class-ID slot, the UV-corner texcoords, the VIF code word, the DAW pointer -- all
of which read a single plausible item as evidence about the whole.
Worth noting what survives. The collision assert string is in SECTION 0 on all 27
levels, so the earlier $gp-relative search located it correctly even though the
reasoning about the file was wrong. The string being in .lit and the file being
.lit are different statements and only the first is true. A wrong reason can reach
a right answer; it is still worth correcting, because the next person to reason
from it would not.
Asserted in overlay_bin_is_the_seven_section_program_not_the_lit_section.
259 tests.
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ReaperOfVeriod
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4ca0308499 |
SBlk body head: the DAW size, stored twice
Picked sound_bank rather than tie, where three discriminators have now come back
negative and a fourth would be guesswork.
The body after the 24-byte head opens with twelve words. Six are settled across
all 27 levels:
word value note
0 varies per level not identified; 27 distinct
1 60 constant
2 varies per level not identified; 23 distinct
3 0 constant
4 daw_size == the header's daw_size, exactly
5 daw_size the same value again
6,7,8 0 constant
9 127 constant
10 1 constant
11 0 constant
Level 0's words 4 and 5 are both 1,482,000, and daw_size is 1,482,000.
THE POINTER THAT WAS NOT ONE
Words 4 and 5 were briefly recorded as pointers into the DAW region. They are not.
The test that promoted them was "does this value fall inside [daw_offset,
daw_offset + daw_size)" -- and the DAW region is ~1.5 MB starting near the front of
a ~1.5 MB extent, so almost any plausible 32-bit word lands inside it. 1,482,000 is
merely just under the top of exactly that range.
A range test is not an identification. What survives is EQUALITY with daw_size,
exact on all 27 levels and asserted, which is a claim that can fail rather than one
that is almost always true.
That is the fourth time this session a plausible reading of a single number has had
to be withdrawn for something falsifiable: the 305x class-ID slot, the UV-corner
texcoords, the VIF code word, and now this. The pattern is consistent enough to be
worth stating as a rule -- a test that passes almost always is measuring the shape
of the data, not a property of it.
Word 0 gets one note: levels 1 and 4 hold 13,042,052 and 13,042,054, two apart,
while their daw_sizes differ by 63,504. Whatever it is, it is not a size.
The remainder of the SBlk body -- the per-sound record table -- is still undecoded,
so sound_bank stays open. A SBlkBodyHead struct carries the twelve words with the
constants asserted in its docs.
259 tests.
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ReaperOfVeriod
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ec433e3341 |
Correct my own "VIF packets" reading: the split is real, the identification is not
Last commit read bit 31 of a tie vertex region's first word as "VIF code word"
and told a two-encoding story on it. The split is real; the identification is
wrong, and I checked it before building anything on top.
Walking those regions as VIF packets, levels 0-2, 914 records:
walk reaches the region end 17
walk dies after exactly ONE packet 1,571
packets before dying: min 0, median 1, max 4
tfrag walks VIF the same way -- VifCode::decode, then num * 4 payload words -- and
reaches the end of its lists every time. So the walk is not the problem; these
regions are not VIF packet streams. Bit 31 is set on whatever this word actually
is, and that is still unknown.
The specific thing that made me overreach: I quoted 0xf5c1a3c5 as "a VIF code
word, cmd 0x75 num 193" and treated that as establishing the format. Decoding one
word as a packet header says nothing about whether the next 193 words are its
payload. Here they are not -- the walk dies immediately after.
This is the third time in this area that one plausible word produced a confident
story: the 305x class-ID slot, the UV-corner texcoords, and now this. All three
shared a shape -- a single readable item at the head of a population, treated as
evidence about the whole. The bit is the only thing the two kinds reliably
differ on, so it stays; the name goes.
The test now asserts BOTH the split and the walk failure, which is the part worth
keeping. If these ever do turn out to be VIF, the test fails and says so, rather
than two findings drifting apart silently -- which is how "half VIF, half flat"
would have sat in the docs indefinitely.
Docs corrected in both roadmap and format file, including the quoted example.
258 tests.
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ReaperOfVeriod
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67ce068c7f |
Tie vertex regions are two encodings, not one; mark Phase 3's port done
Read up on the five commits that landed since |
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 ReaperOfVeriodandreaper
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8030dbf006 |
close: tie LOD distance ordering exceptions - 80/1864 classes have mid=8192 far=8190
Tie class headers ordered near < mid < far on most classes. Measured over all 1,864 classes on all 27 levels, 80 are out of order and they are exact: every one carries mid_dist == 8192.0 and far_dist == 8190.0, so far < mid and lod_for_depth can never return 2 (the far test runs only after mid). Added a golden test asserting the exact pattern, and updated the tie format doc. Co-authored-by: reaper <reaper@users.noreply.github.com> |
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ReaperOfVeriod
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572cd1898d |
Record a defect packet slicing found: the tie block terminator is early
Range measured: every tie LOD block on the disc, 2,177 blocks. The last packet's end is known two ways. Its length comes from its record's packet_quadwords, and every other record's length is confirmed by the next record's pointer -- so only the last packet of each table is unconfirmed. Comparing its computed end against where parse_tie_block stopped: the last packet's computed end lands 2 to 16 bytes past the located 0xf6, on all 2,150 blocks measured. Two readings fit. Either the terminator was located too early -- inside the last packet's data -- or the last packet's length over-predicts by a small amount. The first is likelier: a length error on the last record of every table would have to be a coincidence. Neither is settled here, and the test asserts the measurement rather than the reading. Why the existing test missed it: "2,177 of 2,177 blocks end on 0xf6" is satisfied by a false terminator exactly as well as a true one -- it checks that the byte found IS a 0xf6, not that it is the block's end. A test that confirms the shape it walked to will pass on the wrong byte. The cost: the block extent is short by that much, so payload and padding under-report and anything computed from them is correspondingly short. The block starts are unaffected and RAM-confirmed. Recorded as a limitation with the measurement attached, not fixed. A terminator packet data cannot imitate is its own task, and guessing one would be the plausible-sounding alternative this project has been bitten by. A packets() accessor was tried and removed for the same reason: with the extent short it silently yields the wrong answer, and an API that is quietly wrong is worse than no API. |
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ReaperOfVeriod
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1cfe744501 |
Settle the tie packet length, and correct the retraction that hid it
Range measured: every tie LOD block on the disc -- 2,177 blocks, 13,042
consecutive record pairs.
A record's pointer is where its packet starts, so the distance between
consecutive pointers IS a packet's length, with no reference to any field.
Comparing that against the record's own fields:
packet_quadwords = vert_ofs + vert_size + scissor_size
12,927 of 12,927 record pairs whose strip_count is zero
0 of 115 record pairs whose it is not
The partition is exact: every record with a non-zero strip_count is an
exception and no record with a zero one is. So the fourth term is 0 quadwords
whenever strip_count == 0, and something else -- measured 0..19 quadwords, and
NOT equal to strip_count -- whenever it is not. R&C1's strip_count is a strip
count and strips are variable-length data, so a non-zero count most likely
adds per-strip bytes this cannot see; that is a hypothesis, labelled as one.
TieRecord gains packet_quadwords and packet_quadwords_are_known. The latter is
the honest gate, and the disc test asserts both sides of the partition rather
than the aggregate.
This also corrects this file's own retraction of the same formula, and the
retraction was the error rather than the claim. A formula of this shape was
derived at 61 of 61 pairs, then "retracted" as not reproducing (0 of 13,042).
The re-measurement had swapped strip_count for scissor_ofs in the fourth term
and put the blame on the block set. Re-measured with the term the first pass
had, it matches on 12,927 of 13,042 and the 115 exceptions are exactly the
non-zero strip_count records.
Worth recording because it is the same shape as two other entries in this
file: a retraction is not automatically more careful than the claim it
retracts, and the re-measurement that "disproved" this one changed the thing
being measured. The lesson on the other side is what saved it -- the first
measurement was over 61 pairs, not a population, and had it stayed there the
formula would have looked universal. A small sample and a bad re-measurement,
near-misses in opposite directions.
What this unblocks: the payload can be sliced per packet, which was the
prerequisite for decoding what it holds.
|
||
|
ReaperOfVeriod
|
4abce518e5 |
Decode the overlay's load base, from its own profiler table
Range measured: all 27 levels' overlays. The overlay carries the game's profiler menu definition -- a run of 8-byte padded names (normal, camera, cam+chr, volume, bars, render, mobys, ties, shrubs, cpu/gpu, occl, ...) followed by runs of absolute RAM addresses that point back at those same names. On every level the four addresses after normal/camera/cam+chr/volume, each minus its target name's overlay offset, give the same number: 1,735,792. That is field_00 - 16, where field_00 is the header word that read 1,735,808 on all 27 levels with nothing attached to it. The overlay is loaded with its 16-byte header stripped, so overlay offset X sits at RAM X + 1,735,792. OverlayHeader::ram_address carries it, and the disc test asserts the derivation holds on all 27 levels. Confirmed, not only derived: level 0's RAM 0x1acf80 holds "normal\0camera\0cam+chr\0volume\0", byte-identical to overlay 0x5310, and 0x5310 + 1735792 == 0x1acf80. All four names land where the overlay's own table says. `gc-trace verify-overlay-base` runs that check, savestate-gated the same way as the tie and tfrag ones. The overlay is relocated, not copied: only 37.67% of level 0's is byte-identical at the base, and the 256-entry sine table -- at overlay 0xb650c -- is not at 0xb650c + base. So the base locates the overlay's image, but individual tables inside it move. That is the shape of a loader applying relocations, and it means the base is necessary but not sufficient for reading the game's tables. The value of the base is that any overlay offset can now be carried to a RAM address, which is the prerequisite for reading the game's live level state -- the thing the tie relocation and tfrag lighting checks had to work around. Two things get deleted rather than finished. The collision u16 table was probed four ways -- magnitude distribution, level-independence, run starts, run lengths -- and every one came back level-dependent: the run-start pattern is identical on 1 of 19 levels. So the first 1024 bytes of the collision payload are data, not a fixed table, and nothing was decoded. Recorded as the negative it is rather than left as four half-findings. |
||
|
ReaperOfVeriod
|
55ea619b4c |
Decode the tie class header's +0x0c word: three LOD record counts
Range measured: every tie class on the disc, 1,864 classes over all 27 levels. Method: read the word at class +0x0c as four bytes, and read the record counts independently from the blocks themselves -- follow packets[lod] to the block, walk to the 0xf6 terminator, and count the 16-byte records the block header's data_offset names. Two paths to the same number, so the check is not circular. Result: the byte at +0x0c is the LOD 0 record count, +0x0d is LOD 1's and +0x0e is LOD 2's, on 1,864 of 1,864 classes. Classes with an absent LOD agree too: a zero packets[lod] gives a zero count and the byte is zero. This closes the file's oldest lie about the tie header. The comment in TieClassHeader::parse read "0x0c: the 64 light-slot normals offset. Read past, not decoded" -- inherited from R&C1's layout, where the word genuinely is an offset. On R&C2 it is not an offset at all; it is three counts, and R&C1 carries the same quadruple at +0x20. Skipping the field was the right action on the wrong information: the field was unknown only because R&C1's map was applied to R&C2's bytes. TieClassHeader gains packet_counts, and tie_class_header_counts_records_per_lod asserts the agreement. The fourth byte, +0x0f, is left unnamed. It ranges 1..15, and the obvious following of R&C1 -- the shader/ad-gif total -- disagrees on 1,827 of 1,864 classes, which is 2% agreement where a count would expect 100%. It is recorded as unidentified rather than given a name that fits a fiftieth of the population. |
||
|
ReaperOfVeriod
|
f1f0b517a5 |
Pin the extracted tree, which every disc test reads and nothing verified
data/gc-files.tsv pins the ISO files, and unpacks_and_matches_the_committed_table checks that unpacking reproduces them. But the tie, collision, tfrag and chunk tests do not unpack -- they read ~/Documents/gc-extracted, a directory on disk that nothing in the repository checks. A stale or hand-edited file there would have every measurement built on it still pass, quietly. Three claims this session returned confident numbers while describing the parser rather than the disc -- has_uniform_record_length, "1,509 chunks uniform", the moby class-ID scan -- and a test whose data source is unverified is that same hazard one level down. data/gc-extracted.tsv now records SHA-1 and size for all 5,237 files in that tree, 324 KiB, sizes and hashes only, no content. It is the output of `gc-extract unpack`, whose ISO files are already pinned by the other table, so it is grounded transitively rather than by assertion. the_extracted_tree_matches_the_committed_table walks the table and checks every row's size and hash against disk. It asserts all 5,237 are checked -- so a truncated table fails rather than passing on a prefix -- and reports the first few missing or mismatched paths when it does. Current result: 5,237 of 5,237 match. This does not retroactively validate the three retracted claims. What it does is remove the possibility that any of the surviving ones rests on a directory that could have been anything. 246 tests, clippy clean. |
||
|
ReaperOfVeriod
|
2d3880b624 |
The class-ID retraction goes further: the claim was wrong before the fix
Pinned down the one slot that still cleared 100x after the record-boundary fix,
and it is the artifact this section was written to guard against.
The discriminator the original version lacked: a slot that really carries moby
class IDs must SPAN the ID space, so some of its values land above a level's moby
count. The artifact does the opposite.
type slot enrichment distinct values ABOVE the moby count
0xd76cc453 6 305x 9 0
0xf2ef4275 34 64x 9 341
0xf2ef4275 7 46x 16 412
0xf2ef4275 14 34x 16 432
0xd76cc453 9 32x 28 702
The 305x slot's nine values are 1, 3, 4, 5, 10, 11, 12, 13, 15 -- all under a
level's ~215 moby classes, so every one scores as a hit and 65536/215 = 305x.
Nine small numbers is not a class-ID array. Every slot that actually spans the ID
space scores 10x to 64x, which is chance.
So the original claim's own numbers gave it away and it was not read that way:
"5 to 42 distinct values at 153x to 289x" is exactly the artifact's shape -- a
handful of small values, none above the count. The record-boundary fix was never
what made this claim wrong. It was wrong when written, and the retraction is
complete rather than the partial one I committed two turns ago.
The test now separates the two quantities: slots clearing 100x (currently 1,
expected to remain the artifact) and slots clearing 100x WHILE ALSO having values
above the moby count (currently 0, must stay empty). That second number is the
one that means something, and a slot appearing in it would be the first genuine
evidence of a class-ID array anywhere in the container.
Worth noting the per-SLOT bookkeeping: the count of values above the moby count
is keyed by (type, slot), not by type. A first attempt keyed it by type and the
artifact type passed the check on the strength of its ordinary slots -- 783 of its
own values sat above the count at other slots. The check has to be about the
individual slot, or one good slot launders a bad one.
245 tests, clippy clean.
|
||
|
ReaperOfVeriod
|
d159195510 |
General guard for the over-read class, and the audit showing it was unique
Searched for the pattern that caused the over-read -- a record length derived from
the first difference between two offsets:
grep -rn "\[1\] - \[0\]" crates/gc-formats/src/*.rs
crates/gc-formats/src/chunks.rs:357 (offsets[1] - offsets[0])
One hit, in the one parser that walks an explicit offset table.
The others slice contiguous regions with chunks_exact -- shrub's 8-byte palette
records, tie's 16-byte packet headers, tfrag's 4-byte tables. There a length
cannot run past the next element, because chunks_exact derives each boundary from
the region's own length rather than from a sample of the spacing. Shrub's mesh
packets carry an explicit offset AND size, so they state their length instead of
inferring it.
The damage was bounded by a structural property worth stating: only a format with
an offset table AND a derived stride can over-read, and exactly one format had
both. That is a more useful fact than the retraction was on its own -- it says
where else to look if another one turns up.
The guard is positive rather than a comment.
chunk_records_neither_overlap_nor_leave_gaps asserts across all 27 levels that
every record but the last is exactly its own offset delta long, that there are
1,509 chunks, and that 1,252 have ragged deltas. A regression to a single sampled
stride fails immediately and names the chunk and the record.
245 tests, clippy clean.
|
||
|
ReaperOfVeriod
|
92aa0fe49f |
Audit what the record-boundary fix contaminated: one retraction, one survivor
The fix changed record lengths in 1,252 of 1,509 chunks, so every committed claim
computed over record bytes needed re-checking rather than assuming. All of them:
claim reads verdict
1,509 chunks / 34,491 records offsets unaffected
1,262 chunks with a leading-byte bucket rule record byte 0 unaffected
1,235 chunks with an index rule record bytes 1-2 unaffected
34,432 of 34,491 records 8-byte aligned record byte 0 unaffected
55 strides, all multiples of 4 offsets unaffected
moby class IDs in one slot per chunk type record bytes RETRACTED
17-21% byte positions constant record bytes SURVIVES
Only claims that scanned across a record's BODY were at risk. The rest read a
record's first three bytes, which an over-read never touched -- it appends to the
end. That asymmetry is why the damage was contained to one claim, and it is the
argument for preferring claims anchored at record starts.
The survivor was the obvious candidate for contamination, so it is worth being
precise about it. Re-measured with each record bounded by its successor, and
comparing only the span every record in the chunk has (they are no longer all the
same length):
lowest level 8 16.7%
highest 20.0%
Still inside the documented band. Previously this lived only in a doc comment on
the layout test; it is now asserted, in
chunk_records_share_a_layout_measured_by_constant_byte_positions, over all 27
levels with a 10-30% band so a real change reports itself rather than sliding.
The module documentation is corrected to the measured range and now says outright
that records in one chunk are not all the same length, since that is the fact a
reader would otherwise have to rediscover.
244 tests, clippy clean.
|
||
|
ReaperOfVeriod
|
4fab4d0359 |
Fix the record boundaries after all, and retract a claim built on the bug
I reverted the record-boundary fix last commit on the grounds that "fixed-length
records plus inter-record padding" and "variable-length records" produce the same
offset table. That reasoning was wrong, and cheaply so.
stride is the FIRST offset delta. On the 92, 88, 84, 92, 92, 92, 84, 88 chunk,
if every record were stride bytes long then records 1, 2, 6 and 7 would each run
past the START of their own successor. Records are addressed by an explicit
offset table; they cannot overlap. The padding model is not merely less likely
than variable-length, it is incoherent -- I should have checked that before
reverting a correct fix on the strength of a plausible-sounding alternative.
So: resolve now measures each record against its successor again, with the
overlap argument written into the documentation so it cannot be re-litigated
without someone noticing it is arithmetic.
THE RETRACTION, which is the substantive part:
Three tests broke. Two were straightforward, but the third was not.
* constant_positions indexed records as if they were all the same length. Now
that they are not, it compared past the short ones. It takes the minimum
length instead.
* "1,509 of 1,509 chunks have uniform record length" -- which was true only
because the parser sliced every record at one stride, so the test was
confirming the parser's behaviour back to itself. It now asserts 257 uniform
and 1,252 ragged, and the sum is checked against 1,509 so neither number can
drift alone.
* moby_class_ids_sit_in_one_slot_per_chunk_type asserted >= 20 chunk types
carry a slot of moby class IDs at 38x-289x enrichment. It now finds 2, of
which 1 clears 100x. RETRACTED. That test scored records that carried 4 to 8
bytes of the NEXT record, which read as extra fields and lifted every slot's
apparent hit rate. The general claim -- one class-ID slot per chunk type
across the container -- does not hold. The test asserts 2, asserts 1 strong,
and asserts the count has NOT returned to 20, so the retraction cannot quietly
lapse back into the claim.
That is a committed finding withdrawn on the strength of a parser bug. It is also
the second time in this area that a clean number -- >= 20 types, 1509 uniform --
was really the parser describing itself.
243 tests, clippy clean.
|
||
|
ReaperOfVeriod
|
b9e9835639 |
A parser defect: one chunk type is not fixed-stride, and over-reads
[75 42 ef f2 71 b5] -- the signature that is both level-specific and
variable-length -- makes three chunks per level, 81 total:
stride 76 deltas [76, 76, 76, 76, 76, 76, 76, 76] uniform
stride 92 deltas [92, 88, 84, 92, 92, 92, 84, 88] NOT uniform
stride 104 deltas [104, 104, 104, ...] uniform
Identical on all 27 levels: 27 chunks of each shape, three shapes, no others.
So "this signature has strides {76, 92, 104}" is a misdescription. It has three
chunk shapes, one of which is not fixed-stride at all. The parser derives one
stride per chunk and resolve slices every record at that length.
The cost, precisely: records are read at the offset table's positions, so every
record STARTS correctly -- no misalignment. But each is sliced at 92 bytes, while
two of the eight are 88 and two are 84, so four records over-read by 4 and 8
bytes and carry the head of the next record inside them. Bounds checking holds;
this is a data-correctness bug, not a safety one. It is precisely the kind that
produces plausible-looking fields offset by four bytes, which is how it would
have gone unnoticed had the stride table not been collected per signature rather
than inferred per region.
It also explains why this signature was previously flagged as breaking the 8-byte
alignment rule: its records genuinely are not a uniform multiple.
The right fix is for resolve to use offset deltas for a chunk whose deltas are
not uniform. Not taken here -- the delta sequences are asserted first, so if the
data ever becomes uniform the test fails and asks for the model to be revisited,
rather than the model quietly absorbing the exception.
Asserted in chunk_type_75_ef_has_one_variable_length_chunk_per_level, with the
exact sequences [76x8], [92,88,84,92,92,92,84,88], [104x8] and 27 of each.
A near-miss worth recording, because it would have made a tidy false claim: the
leading u16 of these records appeared to step by exactly 0x50 (80) across all nine
of the 76-byte chunk. Reading at the real offsets gives b1a5, a529, 047e, a529,
04f0, a529, 0562, a529, 05d4 -- no progression at all. The apparent 80-byte step
came from comparing the wrong bytes, and "records are indexed by 80" is exactly
the kind of finding that gets reported on sight.
243 tests, clippy clean.
|
||
|
ReaperOfVeriod
|
af62032ddc |
Most of the chunk container is level-independent: 65 of 74 signatures
Comparing every chunk record against the same record index in the other 26
levels, across all 74 signatures:
65 of 74 every record byte-identical in all 27 levels
9 of 74 level-specific
0 ragged no signature appeared with different record counts per level
The nine that vary:
[5d 44 13] [75 42 ef] [7f 44 ee] [82 c4 2f] [96 c3 37]
[a2 44 a5] [c6 c3 ef] [df c3 ea] [f3 c4 b9]
This reframes the container. 65 of 74 chunk types are static tables the game ships
unchanged in every level -- constants and lookups, not level content. The largest
by record count are all in that group: [38 c4 7e] stride 328 with 90 records per
level, [a9 c4 d8] stride 308 with 90, [3d c4 9e] stride 368 with 77.
The consequence is about method, and it is worth being blunt about. For a
level-specific type, comparing levels is the strongest lever available: a field
that moves with the level is identifiable by correlating it with something known.
For the other 65 there is nothing to compare -- one copy of the data, repeated 27
times -- so they must be decoded structurally, from what the bytes are. A future
decoder that reaches for per-level comparison as its first tool will find it
useless on the majority of the container.
[75 42 ef] is both level-specific AND the one signature with three strides. A
type that is both variable-length and level-varying is the most informative one
here, and is where per-type field decoding should start.
How this was found, including the wrong turn:
The first look at [53 c4 6c d7 9a 43] (stride 108) showed 45 of 108 byte positions
varying WITHIN a chunk and 810 records all distinct -- which reads like per-record
data. Counting distinct values per u32 slot across all 810 records contradicted
that: 29 to 30 distinct values across 27 levels, i.e. about one per level.
Both readings were wrong because they measure different things. The 45 positions
vary between records within a level; the u32 counts were low because the same 30
values recur in every level. Comparing record i across levels settled it: all 30
records are byte-identical in all 27 levels, and zero byte positions vary across
levels.
Had the u32 distinct counts been the only measurement, the conclusion would have
been "one value per level" -- the opposite of the truth, describing a per-level
parameter table that does not exist. The within-chunk and across-level views had
to be taken together to get a true one.
Asserted in most_chunk_signatures_are_level_independent. 242 tests, clippy clean.
|
||
|
ReaperOfVeriod
|
59dba3e58d |
Chunk records: the stride table, and the exception pinned by name
Walked every chunk on all 27 levels, grouped by six-byte header signature:
1,506 chunks, 34,415 records, 74 distinct signatures
55 distinct strides, 52..640, every one a multiple of 4
73 of 74 signatures use exactly one stride
The exception is asserted rather than skipped, because "every type is uniform"
is precisely the claim that quietly stops being true:
[75 42 ef f2 71 b5] strides {76, 92, 104}
That is the variable-length type the module docs had referred to indirectly. It
is now pinned by signature and to those three strides exactly.
The 4-byte alignment is a result, not an artefact. A stride recovered from one
chunk's first-to-second record delta can inherit alignment from where that chunk
happened to sit; collecting all 55 strides across every type and requiring all
of them to be divisible by 4 rules that out, because a single off-by-one in one
signature would show. Asserted in
chunk_record_stride_is_four_byte_aligned_and_uniform_per_signature.
What this settles is the shape the decoder must handle: uniform stride per type,
4-byte aligned, one named exception. Field offsets within a record are now the
same for every record of a type, which is what makes per-type decoding
tractable. The fields themselves are still unnamed.
A layout that did NOT generalise, recorded so it is not rediscovered:
signature [53 c4 6c d7 9a 43], stride 108, 810 records, 63 of 108 byte positions
constant -- 48 bytes varying, then 60 bytes that are zero in every record, then a
constant 0x00010000. That reads like an inline buffer this type never uses, and
would have made a tidy field story. Requiring `stride == live span + zero run`
across every type with 50+ records per chunk gives 0 of 9. The zero tail belongs
to that one type and means nothing general.
Third occurrence of one editing mistake, and it is worth naming as a habit
rather than an accident: inserting a test before an existing one strands that
test's #[test] attribute on the new doc comment and silently unregisters it.
It has now happened three times, each time surfacing only as clippy's "never
used" and never as a missing test. Fixed by appending new tests at the end of
the file instead of anchoring them to an existing function, and verified by
listing registered tests rather than trusting a count.
241 tests, clippy clean, all five recent tests confirmed registered.
|
||
|
ReaperOfVeriod
|
28ab7e094b |
SBlk head characterised: four constants and one word that is not a count
sound_bank's head was parsed but never characterised. Across all 27 levels the
SBlk region opens identically for its first twelve bytes:
+0x00 "SBlk" +0x04 1 +0x08 4 +0x0c "DAW\0" +0x10 0
and +0x14 is the only word that varies. It varies with its low sixteen bits zero
on all 27, leaving 0x0092..0x0103 -- 146 to 259.
That is the shape of a record count, and it tracks the body length at close to
100 bytes per unit. It is not one:
body / field_14 91.2 .. 110.8 across 27 levels
any stride 0..80 with body = stride*word + constant exactly: no
So the test asserts the negative too. If a stride ever makes the relation exact
on all 27, sound_bank_sblk_head_is_constant_apart_from_one_word fails and asks
for the record size to be revisited. A near-miss at 100 bytes/record is exactly
what hardens into a name the next time somebody glances at it; the constants are
also checked individually so a real deviation names which one moved.
The DAW region begins with sixteen zero bytes then block-structured data with
16-byte periodicity and slowly varying nibbles -- consistent with block
compressed audio, not decoded. Recorded as such.
Two mistakes, both mine, both the same shape as earlier ones:
1. The constructor bound `format_tag` with a `let` BEFORE the two words that
precede it in the file, consuming bytes 4..8 and shifting every field after
it. The struct literal listed the names in the right order; the statements did
not. A scratch script reading the same bytes gave the opposite answer, which
is what exposed it. Fixed, with a comment, because "read the lets in file
order" gets undone otherwise.
2. Inserting the new test ahead of an existing one stranded that test's #[test]
on my doc comment -- silently unregistering
tie_vertex_element_is_16_bytes_with_fixed_texcoords. This is the SAME mistake
as two commits ago and I made it again. It again surfaced only as clippy's
"never used" rather than as a missing test. Restored and verified by listing
the registered tests rather than trusting the count.
240 tests, clippy clean, both tie vertex tests confirmed present.
|
||
|
ReaperOfVeriod
|
e86de3c73e |
Tie i16[0..2] are the vertex positions, with a control in the test
The three slots ahead of the index were "unproven position" for want of a test
that could fail. One is available on the disc alone, with the control built in.
LOD 1 and LOD 2 of a tie class are the same object at two levels of detail, so
anything that locates a vertex in that object's own geometry is shared between
the two blocks; a different class' LOD is an unrelated object. Intersecting the
sets of i16[0..2] triples both ways turns "is this a position" into a
measurement. Levels 0-5, ordinary-layout elements only:
same class, LOD1 vs LOD2 96.1% 107 classes, 107 nonzero
different class, control 0.4% 2,144 pairs
A factor of 240. Per level the same-class figure runs 94.4 / 97.9 / 98.1 / 96.7 /
96.8 for levels 0-4. The control stays under 1.0% except for one level-1 pair at
45.9% -- two classes sharing most of their geometry, which is what duplicate or
variant models should look like. Reported, not excluded, and the assertion is on
the mean rather than the max so it does not have to be.
Asserted in tie_vertex_slots_0_to_2_are_shared_positions, including the ratio
(same > 20 * diff) so a change that collapsed both numbers fails rather than
passing twice, and a nonzero-overlap check so no class can silently stop
agreeing with itself.
What this rules out is the point. An index, a handle or a per-vertex counter
would not be shared at 96% between two independently built LOD meshes, nor sit at
0.4% between two objects. With 10.7k-13.2k distinct values per slot over the
full i16 range, these are positions in the object's own frame. Scale and axis
order stay unnamed -- nothing here says centimetres, and axis order is
unconstrained because nothing here assumes one.
Two things worth recording about the process:
1. The diagnostic line printed "1.0%" for 99.4% because the format was
`{same:.1}%` with no `* 100`. The assertions compared fractions and were
always correct; only the readout was wrong. Same family as everything else in
this log -- the readout disagreeing with the claim.
2. Inserting the new test in front of an existing one stranded that test's
#[test] on my doc comment, which silently unregistered
tie_vertex_element_is_16_bytes_with_fixed_texcoords. It showed up as
"never used" in clippy, not as a missing test. Restored; both tie vertex
tests are registered and 239 tests run.
Element layout now reads:
+0x00 i16[0] position x +0x06 u8 index 0..=254
+0x02 i16[1] position y +0x07 u8 layout tag, 0 in 93.4%
+0x04 i16[2] position z +0x08 i16[4] texcoord u
+0x0a i16[5] texcoord v +0x0c/+0x0e i16[6], i16[7] unnamed
|
||
|
ReaperOfVeriod
|
06cf2fd46d |
Tie vertex slot 3 is a byte-sized index, not a coordinate
Splitting the 95,612 elements of levels 0-2 by i16[3]'s HIGH byte, which is the
layout selector:
0x00 89,341 93.4%
0x03 5,344 5.6%
144 other selector values 927 1.0%
146 selector values in all. Not a two-way switch, and the second case is not 0x01.
Inside the ordinary layout i16[3] is not a coordinate: 201 distinct values, all
within 0..=254, with 0 most common. That is an index. So the selector and the
index are not two independent halves sharing a slot -- it is one byte. The low
byte is the index, the high byte is the layout tag, and the ordinary layout never
sets the high byte. Asserted.
Nearly got this wrong twice, both times the same way, which is why they are in
the commit message:
1. The first pass gated the range on `w >= 0` instead of on `(w >> 8) == 0`,
letting in the other layouts' large positive values. That reported "564
distinct values in 0..=32664" -- a number that looks exactly like a
coordinate and is really two populations unioned. The selector byte is the
filter. The filter is part of the claim.
2. Two constants were guessed rather than measured (selector cardinality 159,
and an upper bound that ignored non-ordinary layouts) and both were wrong.
The cardinality is 146. Guessing a constant and then asserting it is how a
measurement becomes a tautology.
Quantified the i16[6]/i16[7] question while I was in here, because "both are
multiples of 4096" has been sitting in the docs as a fixed-point signal:
both %4096==0 in 86.5% of elements
expected if the two residues were independent: 84.3%
enrichment 1.0x -- exactly chance
They look like a fixed-point pair only because their dominant values, 4096 and 0,
are both multiples of 4096. Remove the constants and it is gone: of the 7,316
elements where i16[6] differs from 4096, only 36.7% are still multiples, and of
the 9,905 where i16[7] differs from 0, ONE is. The disc test had already refused
to call that pair a texcoord for this reason; now the reason is a number.
Remaining slots in the ordinary layout, recorded: i16[0..2] read as position but
are unproven (10.7k-13.2k distinct each, full i16 range), i16[4]/i16[5] are the
texcoords, i16[6]/i16[7] unnamed.
Also fixes two clippy map_or lints and an import that a stray --fix had broken.
238 tests, clippy clean.
|
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ReaperOfVeriod
|
26a0918178 |
Gate the PCSX2 claims as tests; two corrections fall out of writing them
The audit two commits ago listed three claims as "not assertable here -- needs a
savestate". With PCSX2 running they are assertable, so they now are. gc-trace
already exposed gc_trace::Savestate::ee_ram_owned(); gc-extract just needed it as
a dev-dependency. Both tests are gated on GC_SSTATE and skip cleanly without it,
so a normal checkout pays nothing.
Writing them corrected two claims, which is the main reason they were worth
writing as tests rather than staying prose.
1. The collision payload is NOT "byte-for-byte identical". The original claim
rested on a 4 KiB probe; the test compares the whole 903,248-byte payload:
payload 903,248 bytes at RAM 0xac6800
first difference +0xdc82c, i.e. 903,212 bytes in
bytes that differ 6 (0.00%)
903,212 of 903,248 bytes are verbatim and 6 are not, all in the final 36.
"Verbatim" was an overclaim on a probe that never looked at the tail. The test
now measures the whole payload and reports the extent, asserting only that the
divergence is beyond the head.
2. The tfrag relocation base is the TABLE address, not the block base. The delta is
8,683,584 = 0x848040 = block base 0x848000 plus table_offset 0x40 -- which is
exactly what TfragHeader::data's own documentation says, "relative to the
table". The earlier claim said "the block's RAM base", off by exactly the table
offset.
Also: +0x10 and +0x38 do NOT share one constant. The aggregate "1,665 fields
relocate by one constant" was true only because +0x10 carried it; lumping them
hid that. The test asserts +0x10 and REPORTS +0x38's delta rather than assuming.
The patch-rewrite figures also restated on aggregate rather than median, which is
why they read lower than the 7.80%/8.12% medians recorded earlier:
patch bytes rewritten -- cannot morph 1.9% of 334, can morph 2.1% of 499
Same conclusion, stated on a total instead of a per-patch median, and asserted to
within 3 percentage points of each other.
Net: the audit table in docs/formats/core-data-regions.md now has no "prose only"
rows for disc-or-savestate-readable claims.
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ReaperOfVeriod
|
9f938f47de |
Assert the tie vertex layout finding in a test, and audit which claims are asserted
The i16[3] high-byte finding -- the most recent and most subtle result of this stretch, and the one I corrected twice -- lived only in prose. Two commits is exactly how long a claim can sit unasserted before it drifts. It now has a test: tie_vertex_layout_is_selected_by_i16_3_high_byte which reproduces the figures exactly and, importantly, asserts both directions: (4,5) and (6,7) are above 0.85 and 0.80 in the ordinary group, (6,7) is BELOW 0.99 so it cannot silently become the constant I once mistook it for, (0,1) and (2,3) are under 0.20, and every pair in the non-zero group is under 0.15. A future change in either layout now fails loudly. Also audited the rest of this session's claims against the test suite and recorded the result in the format doc: tie vertex element is 16 bytes asserted layout selected by i16[3] HIGH byte asserted (this commit) blocks self-delimiting on 0xf6 asserted per-block packets == 0 means no block at that LOD asserted packets[0] == 256 on 1,864 of 1,864 asserted chunk record length uniform per chunk asserted moby class IDs in one body slot per type asserted collision payload verbatim in RAM NOT assertable here -- needs a savestate tfrag patch bytes all rewritten by LOD same morphing is unobservable in that image same The split is deliberate: disc-readable claims are asserted against the disc, savestate-dependent ones live in plan/pcsx2-verification.md with their method. What is not acceptable is a disc-readable claim living only in prose -- which is how the tie i16[3] finding spent two commits before it had a test, and how several older claims drifted before the roadmap reconciliation caught them. |
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ReaperOfVeriod
|
180fc27b04 |
Locate the tie texcoord field at i16[4]/i16[5], and rule out the (6,7) artifact
Scoring each adjacent i16 slot pair of the 16-byte tie vertex for 12-bit fixedness over 36,501 level-0 vertices locates the fields: (i16[0], i16[1]) 1.1% not a texcoord (i16[2], i16[3]) 4.8% not a texcoord (i16[4], i16[5]) 73.6% <- the texcoords (i16[6], i16[7]) 76.6% <- the near-constant 4096/0 pair (6,7) scores HIGHER and is not a texcoord. It is the near-constant 4096, 0 pair: 4096 is 1.0 in 12-bit fixed and 0 is zero, so both are trivially multiples of 4096. That is the constant artifact again -- a fixed pair would score 100% anywhere. The field is (4,5), with (0,1) and (2,3) ruled out at 1.1% and 4.8%. The first four slots span the full i16 range with 10,803 to 13,421 distinct values each, so they are neither texcoords nor small fields. The vertex base is confirmed to be vert_ofs alone. Adding the shader or control region makes it worse -- vert_ofs only 73.6% bfc + vert_ofs 69.8% bfc + control_count*control_size + vert_ofs 66.7% -- so the 73.6% residual is not a mislocated base. Worth recording because vert_ofs (3..7) numerically overlaps the shader region (5*shader_count, 5..20 quadwords), which made a combined base look plausible; measurement says the simple one is right. The test asserts (4,5) above 60% and (0,1)/(2,3) below 5%/15%, and names the (6,7) artifact in its failure message so the higher-scoring pair cannot be mistaken for the answer later. |
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ReaperOfVeriod
|
35b087c882 |
Establish the tie vertex element is 16 bytes, and correct the roadmap's tie entry
With TieRecord identified as RAC1's TiePacketHeader, each record's leading word points at its packet in the block payload. Following it and stepping vert_size elements from vert_ofs reaches the vertices: 95,612 of them on levels 0-2. Element size settled by comparison, not assumed. Requiring the texcoord pair to be 12-bit fixed -- both words multiples of 4096, which is how 0x1000 = 1.0 reads: element 16 bytes : 78,919 / 95,612 = 82.5% element 8 bytes : 45,661 / 95,612 = 47.8% element 12 bytes : 44,834 / 95,612 = 44.8% Sixteen wins by a factor of 1.7 over the nearest alternative. Observed layout, 8 x i16: the first three slots span the full i16 range with 10,803-13,421 distinct values each; i16[4] and [5] are the texcoords and are both multiples of 4096 on 82.5%; i16[6] reads 4096 on 85.8% and i16[7] reads 0 on 84.0%. Not established: what any field means, and why the texcoord rate is 82.5% rather than 100%. The residual tracks record shape -- (shaders 2, control 7, size 2) hits 60%, (shaders 1, control 18, size 5) hits 89% -- so it is not one bad block but something per-packet this reading does not capture. Worth recording that this is the OPPOSITE of what the disc alone concluded two commits ago. Reading the header word at +0x00 as an element count gave 0 of 922 blocks dividing; it is the byte offset to the payload, so the table it bounds has 16-byte records. The number was right and the reading was wrong, which is what the packet-header identification corrected. The roadmap's tie entry was also stale -- it still said "a 16-byte record is withdrawn", which the packet-header work had already reversed. Rewritten from the commits: both indirections, self-delimiting blocks, the TiePacketHeader identification with its 15,219/15,219 rule, the 16-byte vertex element, and what remains open. A test asserts the element size against both alternatives so the 82.5% figure cannot be quietly replaced by an assumption. |
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ReaperOfVeriod
|
54862b64ee |
Identify the tie record as RAC1's TiePacketHeader, and retract a formula
The 16-byte tie record is R&C1's TiePacketHeader offset for offset: a data pointer at +0, then R&C1's byte fields at +4 through +0x10. The identification is not a resemblance but R&C1's own rule -- bfc_distance == 5 * shader_count -- holding on all 15,219 records of all 2,177 blocks on all 27 levels. Measured over the same set, and reported rather than asserted where it is not universal: bfc_distance == 5 * shader_count 15219 / 15219 vert_ofs <= vert_size all scissor_size <= scissor_ofs all control_size <= control_count all color_ofs == vert_size 12640 / 15219 color_ofs == vert_ofs + vert_size 0 / 15219 color_count, strip_count, strip_vertex_count zero 15089 / 15077 / 15078 R&C1's rule for the colour offset holding on none of them is the interesting line: the two games use that field differently, so it is named color_ofs for what this game's majority reads as and the 2,579 exceptions are counted rather than averaged away. TieRecord parses all twelve fields, invariants_hold asserts only the universal four, and the disc test counts the rest. A packet-length formula is withdrawn rather than softened. (vert_ofs + vert_size + scissor_ofs + scissor_size) * 16 was measured at 61 of 61 pairs and is not reproduced on the correct blocks -- 0 of 13,042. The block set was the error, not the arithmetic: the script that produced the 61 read packets[2] where packets[1] was meant, so it measured 461 blocks instead of the 2,177 the class tables define, and the formula agreed perfectly with a population that was not the tie blocks. TieRecord::packet_bytes goes with it, and the retraction is recorded in the format doc and in the struct. That misread also explains why the earlier RAM verification saw different numbers for the two inputs -- same lesson as rule 3, arriving through a wrong subscript instead of a wrong span. |
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|
ReaperOfVeriod
|
e6eecb871f |
Decode the tie LOD block: it is a table of 16-byte records
The tie block's word at +0x00 was read as an element count, and the reading failed in a way worth recording: the payload length divided by it is a whole number on 0 of 922 blocks, at any record size and any header up to 512 bytes. That is the correct measurement of the wrong hypothesis -- the word never described the payload. Range measured: every LOD block of level 1 whose word is a non-zero multiple of 16, plus the two read by hand in full. Method: locate each block's record table in PCSX2's RAM by its twelve field bytes, which are the only distinctive 12-byte run in a block, then compare every record against its disc copy. Each block has several copies in RAM, and the one that matches is the loaded one -- checking the first hit is what made the first attempt report 0 of 16. Result: on 16 of 16 blocks, every record's leading word has become table_address + word, and the other twelve bytes are byte-identical to the disc. So a block is [16-byte header][record table][vertex payload], the records are 16 bytes -- a leading u32 pointer plus twelve bytes of fields -- and the header's word at +0x00 is the byte offset from the block start to the payload, that is, the length of the table. That is what the multiple-of-16 was: the table holds 16-byte records. It is never zero because there is always at least the first record, and its 42 distinct values are table lengths. Each record's pointer is relative to the table start, relocated at load to table + word. TieBlockHeader::data_offset and TieBlockHeader::records carry it, bound by the offset, with TieRecord for the twelve field bytes, and the disc test asserts the table is bounded on every block. What the records' fields name and what the payload holds are still open -- the payload is known to be variable-length, float-shaped, not LZ77 and not VIF1. |
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ReaperOfVeriod
|
c2af0528e3 |
Correct the chunk loader finding and decode a record field
The loader note said every record gains a 02 00 prefix in RAM. It does not: the word is the record's own leading field, already on the disc at every record. What the loader changes is the pointer -- it addresses the word, two bytes earlier than the disc's table -- and that pointer shift is what made the bytes look inserted. Measured, in order: - the two bytes before a payload are identical in core_data and in RAM, record for record: 02 00 on level 0's 90-record chunk at 0x100b302, 08 00 on the level's first chunk. Nothing is inserted; - the RAM table's low 24 bits are the payload's minus 2, consistently, so the record is [leading u16][two index bytes][payload] and the loaded table addresses the leading word. That is also why the index bytes read as +2 from the pointer -- the same +2 the earlier RAM result quotes; - the word is a field, not a pad: uniform across a chunk's records on 1,439 of 1,509 chunks (None on the 70 that vary, reported rather than averaged), fixed within all 71 chunk types, and only ever 1, 2, 4, 6, 8 or 10 -- 554 chunks carry 2, 520 carry 4. Two readings of the value were measured and disproved, so they are recorded as disproved rather than left as candidates: it is not an entry count (the payload divided by it leaves 57 distinct fractional "sizes", and 162 chunks do not divide at all), and it is not the number of distinct leading bytes (agrees on 0 of 1,506 chunks). Chunk gains `prefix: Option<u16>`, and the disc test asserts the uniformity, the per-type fixity and the value set. The scratch example that produced the per-type class-ID table is dropped now that the same scan is a committed test, which also lands here: moby class IDs sit in one body slot per chunk type, with the slot varying by type and the distinct >= 4 filter load-bearing -- without it the top slots are constants that read as 305x because any value below the moby count counts as a hit. |
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|
ReaperOfVeriod
|
28680b4be3 |
Show the first two chunk-record bytes encode the record's own index
Continuing from the phase counter. Within a chunk: i : 0 1 2 3 4 5 6 7 8 9 10 11 ... 15 16 17 ... byte0: 0 16 32 48 64 80 96 112 128 144 160 176 ... 240 0 16 32 byte1: 0 0 0 0 0 0 0 0 0 0 0 0 ... 0 1 1 1 byte0 is step*(j mod g) and byte1 is (j / g), where g = 256/step and j = index + phase. The pair is the record's index in mixed radix: byte0 carries the low digits scaled by step, byte1 the quotient. Measured over all 27 levels: 1,235 of 1,509 chunks fit this on both bytes. Byte 0 alone fits 1,262, so the 27-chunk difference are chunks whose first byte follows the rule and whose second does not. On 1,235 chunks a record knows its own position and the two leading bytes hold no per-record information. ResolvedChunk::index_rule returns the (step, phase) only when the whole chunk fits on BOTH bytes, so the 274 that do not stay distinguishable and nothing skips a leading byte on a rule that does not apply to it. A number that moved when the implementation changed: a first probe reported 1,181; the committed method reports 1,235. The method is right. The probe accumulated ok0/ok1 flags across candidate phases with an early-exit that could skip a phase which would have matched both bytes, and it also disagreed with bucket_rule on the byte-0 count (1,208 against 1,262), which is what gave it away. Recorded because both numbers came from the same run and only the discrepancy exposed the probe as wrong. The lesson is narrow: when a one-off probe and a committed helper disagree, check the probe first. |
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|
ReaperOfVeriod
|
79914c420e |
Show the chunk record's leading byte is a per-chunk phase counter; every chunk
has a uniform record length Follows the alignment result and settles what the leading byte is. Within one chunk the leading byte steps by a constant and wraps: offsets: 1420 1748 2072 2392 2716 3044 3372 3700 4028 4352 ... byte0: 0 16 32 48 64 80 96 112 128 144 ... Sweeping every (step, phase) over all 27 levels: fully explained: 1,262 of 1,509 chunks by step: 8 -> 51 chunks, 16 -> 554, 32 -> 520, 64 -> 137 unexplained: 247 chunks across 11 chunk types So on 1,262 chunks the leading byte carries no per-record information: it is a deterministic function of the record's index and the chunk's phase, which is a position marker rather than data. That is why the earlier "16 discrete values, uniform counts" pattern appeared at all. ResolvedChunk::bucket_rule returns the (step, phase) when the whole chunk fits and None otherwise, so the 247 unexplained chunks stay distinguishable and nothing skips a leading byte on the strength of a rule that does not apply to it. Every chunk has a uniform record length: 1,509 of 1,509. Length varies BETWEEN chunks of a type -- one type runs 76 to 104 bytes -- but never within one. This withdraws the previous commit's "variable-length type", which came from pooling minlen/maxlen across all of a type's records at once. That is the pooled-claim error rule 3a exists to prevent, and it is the third time this session a pooled measurement produced a claim that partitioning reversed. The type is not variable-length; the chunk is fixed-length and different chunks differ. |
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|
ReaperOfVeriod
|
a9bf74fc10 |
Characterise all 77 chunk types: record byte 0 is a bucket index, not data
Characterised every chunk type -- 77 of them, 1,509 chunks, 34,491 records, all 27 levels. Byte 0 of every record is a small aligned index, not record content. It takes 16 discrete values per chunk type (0x00, 0x10, ... 0xf0) with near-uniform counts WITHIN each type. Uniform weighting is the tell: a running byte offset would weight the buckets unevenly, because records differ in size. type_id recs len byte0 0x007d7ec438 2430 328 0x00:162 0x10:162 0x20:162 ... 0xf0:135 0x00429ec43d 2079 368 0x00:162 0x10:135 0x20:135 ... 0xf0:108 0x00d76cc453 810 108 0x00:27 0x08:27 0x10:27 ... 0xe8:27 <- steps by 8 The alignment step is per type, not global. The leading byte is a multiple of 8 on 34,432 of 34,491 records but a multiple of 16 on only 33,349 -- the 1,142-record difference falls in seven types, four of which step by 8. 59 records in three types break even the 8-byte rule, and that is where the variable-length type lives: 0x00f2ef4275, records 76 to 104 bytes, no single stride to align to. What the bucket indexes is NOT named. It is reported as CHUNK_RECORD_ALIGNMENT and record_is_aligned rather than as a parsed field, because naming it would be a guess while the invariant is solid. The test pins the exact exception set -- 59 records across 3 types -- so a change there fails loudly. A measurement I initially got wrong: the first version of the constant claimed a 16-byte multiple on 34,432 records. 34,432 is the multiple-of-8 count; the multiple-of-16 count is 33,349. Right number, wrong label, and the test caught it. That is the second time this session a correct number carried a wrong label, after the tie four-value retraction. Both times the assertion did, which is the argument for putting these numbers in tests rather than only in prose. Still open: what the bucket indexes, and the remaining record fields. |
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|
ReaperOfVeriod
|
291153a0d9 |
Find the tie LOD block terminator; packets == 0 means no block at that LOD
parse_tie_block walks to a 0xf6 terminator that every real block carries, on
2177 of 2177 across all 27 levels, followed by zero padding. This is what makes
the blocks parseable: packets[1] bounds one on only 461 of 1864 classes, so the
terminator is the only general way to find one.
The terminator was worth a control, because 0xf6 could have been byte-frequency
coincidence. It occurs in payloads at 0.83x the uniform rate -- slightly LESS
often than chance -- while the last non-zero byte is 0xf6 on 909 of 922 blocks in
the first subset, against 17 of 922 for the same blocks cut at a random point. So
it is a terminator, not a common byte.
packets == 0 means the class has NO block at that LOD: of 3,728 (class, LOD)
slots, 2177 point at a block and 1551 are exactly zero.
Corrected header, over all 2177:
+0x00 count multiple of 16 on all; 42 distinct; never zero
+0x02 zero on all
+0x04 exactly four values: 0x501 (1069), 0xa02 (720), 0xf03 (350),
0x1404 (38)
+0x06 16 distinct, never zero
+0x08 180 distinct, never zero
+0x0a 61 distinct, never zero
+0x0c 125 distinct, never zero, clustered 0x043f..0x0443
+0x0e 11 distinct, zero on 2162 -- the only non-universal field
+0x0c clusters around 1087-1091, close enough to a block length to be worth
stating, but it is NOT the length: the difference against the true payload length
scatters from -12 to -172.
A correction to the previous commit. It reported 3,728 blocks all terminating and
packed_texture taking 842 distinct values, and on that basis retracted the
four-value claim. Both numbers were wrong the same way: the scan did not skip
packets == 0, so it computed class_base + 0 and walked forward from the CLASS
BODY, finding a terminator there by accident. That contaminated 1551 of the 3728.
With the zeros excluded the slot takes exactly four values on all 2177 blocks.
The four-value claim was right; my retraction of it was wrong; and the retraction
was made on a number from the same contaminated set. A retraction is not
automatically better than the claim it retracts -- it needs its own bounds.
Still open: the payload's records. Established this round: blocks are
self-delimiting, absent LODs are marked by a zero packets word, and the header is
fully characterised. Not established: any record boundary inside the payload,
which stays variable-length.
|
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|
ReaperOfVeriod
|
02342de31b |
Decode the tie LOD block header; establish the payload is variable-length
TieBlockHeader parses the block's own 16 bytes, measured over the 922 blocks where "the next packets offset ends this block" holds, across all 27 levels. A real-disc test asserts every figure. +0x00 count multiple of 16 on 922/922; 16..2096; 72 distinct disc-wide +0x02 zero on 922/922 +0x04 ONE OF FOUR VALUES DISC-WIDE: 0x501, 0xa02, 0xf03, 0x1404 +0x06 15 distinct, 0x0206..0x0512 +0x08 135 distinct, 0x0b05..0x4ee4 +0x0a 45 distinct +0x0c 94 distinct, 0x010e..0x0553 +0x0e zero on 914/922 +0x04 is packed rather than a magnitude: four values across the whole disc with the two bytes moving independently, low 1-4 and high 5/10/15/20 in lockstep. That it is a texture index paired with a scale is a guess; that it is two fields is not. The count is not a record count -- block_size minus the header is divisible by it on 0 of 922, for any record size and any header up to 512 bytes. On the payload, a control was needed and changed the answer. Reading blocks as 3 x f32 triples, 53-64% of reads land within +/-5000 of origin, against 16% for a uniform-random control of identical length. So the content is float-shaped and genuinely not random. But the rate is flat across every start offset and every stride tried, 53-65% throughout. A statistic that cannot separate the right stride from the wrong one cannot identify a stride -- rule 4's exact case. Flatness plus a count that does not tile means the records are variable length. That killed two readings. A VIF1 command walk consumes 0 of 88 blocks exactly, so it is not a VIF1 CPU-format stream. wad::decompress rejects the block at every start offset, so it is not WAD LZ77. Scanning every (start, stride) pair from 0x10 to 0x7f for byte positions with a small distinct-value vocabulary finds none: every position takes all 256 values at every alignment. For float payload that is expected, so the scan found nothing rather than confirming anything -- worth saying, because "no fields found" here is uninformative, not evidence against fields. Still open: what the payload holds. Established: variable-length, float-shaped, non-random, not LZ77, not VIF1. Not established: any record boundary. |
||
|
ReaperOfVeriod
|
855e640f39 |
Establish the 16-byte tie record on measurable classes; packets[0] is a constant
The previous commit reported "3580 non-empty LOD blocks compute as divisible by 16" and then said the figure should not be trusted, because it came from the "next packets offset ends this block" rule. That rule is unsound: packets is strictly increasing on only 461 of 1864 classes. On the other 1403 the two offsets are unordered and cannot both be block starts into one ascending region. Restricting to the 461 classes where the rule does hold, 922 of 922 consecutive block sizes are a multiple of 16. That is the evidence for a 16-byte record, and it is now scoped to the subset where it can be checked rather than claimed over all 1864. The other 1403 are unmeasured, not measured-and-different. packets[0] is a constant, not an offset: it reads 256 on 1864 of 1864 classes, while packets[1] and packets[2] vary widely and land at different addresses in core_data on every class. Read as a block start, 256 points just past the 0x48-byte header -- which is how it was being used, and exactly how a field gets mistaken for a pointer. It is now TIE_PACKETS0 and nothing depends on it. Still not decoded: what the 16 bytes hold. i16[0] at +4 takes 8969 distinct values on level 0 and is not the two-valued field a 12-unit sample suggested; the word at +0 is not a run offset. The test pins all four numbers -- packets[0] constant, the 922/922 divisibility, the 461/1864 ordering, and the 0/1864 monotonic disproof -- and asserts that the ordering is *not* universal, so a future change there fails loudly instead of quietly invalidating the record size. |
||
|
ReaperOfVeriod
|
60e3f129d8 |
Resolve both tie indirections on all 1,864 classes, and disprove a sample artifact
resolve_tie_class walks the chain, which is two steps and both are easy to get
wrong:
1. The tie class table lives in core_index.bin, not core_data.bin. On level 0
the tables chain as moby at 192, 238 x 32 bytes later tie at 7808, 74 x 32
later shrub at 10176, which closes. Reading the same table out of
core_data.bin produces plausible garbage rather than an error.
2. ClassEntry::offset_in_asset_wad addresses core_data.bin, despite the field
name and despite core_data.wad sitting alongside it.
Verified: all 1864 tie classes resolve, o_class agreeing on every one, and all
5592 LOD block offsets land inside core_data.
Disproved, and this is the part worth reading: the word at +0 of a 16-byte unit
inside an LOD block. On the first twelve units of level 0's class 0 it rises
strictly -- 288, 1520, 2848, 3968, 5088, 6096, 7312, 8528, 9792, 10976, 12016,
13072 -- which reads exactly like a linked list, and the accompanying i16s looked
quantised, two distinct values in i16[0] and three in i16[1].
Across the population it is strictly increasing on 0 of 1864 blocks, and i16[0]
takes 8969 distinct values on level 0 alone rather than two. The sample was
twelve units out of 1,724,334. Both the monotonic reading and the quantisation
were artifacts of that sample.
That is the pooled-claim error AGENTS.md rule 3a exists to prevent, committed
almost verbatim: the first twelve units looked clean, and I was one step from
writing "u32[0] is a linked list of runs" into a format spec. The test now
asserts the disproof, so it cannot creep back.
Not established: the block's record size. 3580 non-empty LOD blocks compute as
divisible by 16, but some packets offsets run backwards, so the "next offset
delimits this block" end is wrong for them and that figure should not be trusted.
The tie layout stays partial: indirections and header done, records not.
|
||
|
ReaperOfVeriod
|
02ced5ee83 |
Parse the per-level overlay: header, constant block, level data
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. |