From 3855169d4801b7ea4779baca9d7e13ba664222ef Mon Sep 17 00:00:00 2001 From: ReaperOfVeriod Date: Sun, 11 Oct 2026 03:45:01 +0200 Subject: [PATCH] Characterise sky sub-object 0: sparse, with duplicated entries Range measured: level 0, sky region +365760..+388880, 23120 bytes, read as 2890 records of 8. The matched-control autocorrelation puts the peak at stride 8 (0.217 real, 0.000 shuffled), so 8 is the unit to describe. Composition: 1185 distinct u32 values across 5780 words; a mean of 6.99 of every 8 bytes are zero, so most records are sparse; and 549 of 2890 adjacent pairs, 19%, are exact duplicates of each other. The most common 8-byte record appears 283 times and is d7d7d780 d7d7d780 -- a 4-byte value stored twice. Others follow the same shape: 00051980 00051980, 00082580 00082580. Not decoded. Sparsity with repeated entries is what a keyframe or index table looks like, but nothing here establishes that, and the duplicated-4-byte shape may just as easily be two adjacent records sharing a value. Recorded as a characterisation with its range rather than a finding, because that is what it is. The useful part is that the next attempt does not have to re-derive the composition to know whether a decode is plausible. --- docs/formats/core-data-regions.md | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/docs/formats/core-data-regions.md b/docs/formats/core-data-regions.md index cf5c700..309f6bd 100644 --- a/docs/formats/core-data-regions.md +++ b/docs/formats/core-data-regions.md @@ -355,3 +355,28 @@ content rather than being fixed. **Level 2's header remains genuinely different**: its count field at `+0x0c` reads 196,617 and is unusable, while every other level yields a plausible count. Whatever makes it different is still unexplained. + +### Sky sub-object 0: sparse, with duplicated entries + +**Range measured:** level 0, sky region `+365760 .. +388880`, 23,120 bytes, +read as 2,890 records of 8. + +**Method:** record composition, plus the adjacent-pair and zero-density +statistics below. The matched-control autocorrelation puts the peak at stride +8 (0.217 real, 0.000 shuffled), so 8 is the unit to describe. + +**What it is made of:** + +- **1,185 distinct `u32` values** across 5,780 words. +- **Mean 6.99 of 8 bytes are zero**, so most records are sparse -- one or two + live bytes in eight. +- **549 of 2,890 adjacent pairs (19%) are exact duplicates of each other.** The + most common 8-byte record, appearing 283 times, is `d7d7d780 d7d7d780` -- a + 4-byte value stored twice. Others follow the same shape: `00051980 00051980`, + `00082580 00082580`. + +**Not decoded.** Sparsity plus repeated entries is what a keyframe or index +table looks like, but nothing here establishes that, and the duplicated-4-byte +shape may equally be two adjacent records that happen to share a value. +Recorded as a characterisation, with its range, so the next attempt starts +from the composition rather than re-deriving it.