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thejayman77 ba74bbd5aa Snapshot: fog implementation + fidelity tooling baseline (pre bilinear-clamp fix)

Per-vertex GS fog end-to-end (gs_stub emit incl. persp_emit5, gs_prim_list_feeder
XYZ2->XYZF2 on PRIM.FGE, gs_make_sh3_scheduler_fixture.py F/FGE packing), new fog
TBs, fidelity attribution tooling. Functional baseline before removing the dead
bilinear lerp8 clamps (Codex: 161-node comb loop -> -0.042ns setup fail).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

2026-07-20 19:56:46 -04:00

4.6 KiB

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Ch357 audit log — NATIVE 640×480 LPDDR framebuffer

Codex rung after Ch356. The Ch356 N-texture scheduler on a native 640×480 LPDDR framebuffer. Draws land at their authentic screen coordinates (the Ch356 union-origin translation is removed). The scheduler and host are unchanged from Ch356 — only the framebuffer geometry differs. Same 3 epochs (dump order): E0=idx11671, E1=idx19562, E2=idx89761.

Geometry (Codex's spec — all gated in the fixture generator, fail-closed)

FBW=10, stride 2560 B, FB size 0x12C000 (1,228,800 B), 80 beats/row, 38,400 beats/frame.
authentic coords (no union translation): draws span x[170..490] y[9..390] — fit inside 640×480 (gated: fail-closed if any vertex escapes).
FB region [0, 0x12C000) disjoint from the texture region [0x200000, 0x240000) (gated).
texture kept at 0x200000 (single-region cache), unchanged from Ch356.

Tooling — `gs_make_sh3_scheduler_fixture.py --fb640 --emit`

new --fb640 mode: native 640×480, OX=OY=0 (no translation), geometry/fit/disjoint gates, distinct fixture prefix sh3_s640 so Ch356 (sh3_sched) and Ch357 (sh3_s640) fixtures coexist. Ch356 output byte-identical (verified).
emits: feeder_sh3_s640{k}.mem, sh3_s640{k}_tex_lpddr/idx/pal/refmap.mem, composed sh3_s640_refmap.mem, bootlet bios/payload_sh3_s640 (preloads all N relocated CLUTs), sh3_s640_params.vh, descriptor table sh3_s640_epochs.txt.
composed-reference pixel counts (42414 covered / 6124 multi-epoch) MATCH Ch356 exactly — translation-invariant, a good cross-check.
Q-canonicalization self-test PASS.

Integration sim (tb_top_psmct32_sh3_sched640) — PASS

preclear once; 3 FRESH cache fills (CRC 0x26a88b77/0x95a83cbc/0xfbdeaa32, beats=8192, rd_errs=0); 3 lists STREAMED via the feeder write port (word0=68 each); 3 FRESH ORDERED drains (E0 low→high; E1/E2 high→low→high); records=68 each; ovf=0.
scanout held off until the last drain; scanout beats/frame = 38400 EXACT (the PASS verdict gates on this $error check); underflow=0, rd_errs=0; full 640×480 frame scored.
oracle: ALL=94.1% ≤1texel, MULTI(≥2)=92.7%, clut_bad=0 (reciprocal-limited fidelity, same as Ch356; not accumulation).

Accumulation correctness — 100% BIT-FOR-BIT on the FULL 640×480 frame (`make tb_top_psmct32_sh3_sched640_compose`)

render ALL + each epoch in isolation (+ONLY=k +FBDUMP), composite (nonzero-wins DECAL, compose_sched.py --width 640), compare to the joint ALL render.
307200/307200 px, 0 mismatch — 100.0000% BIT-FOR-BIT. Full-frame reference; accumulation exact on the native FB.

Host — UNCHANGED (proves "scheduler unchanged")

the SAME ps2_sh3_sched binary drives the 640 descriptor table: reads fbwords from the META line (307200), preclears 0..0x12C000, iterates the same per-epoch flow. Dry-run green (all 3 CRCs, 619 words each, rc=0).
BOARD RUN: sudo ./ps2_sh3_sched sh3_s640_epochs.txt.

Board prep — fit-ready, owner-gated

de25 top: new GS_SH3_LPDDR_FB_640 branch → SCANOUT_LB 2560/80/480 + FEEDER_STG_WORDS=2048. Elaborates clean under GS_SH3_LPDDR_FB+_640+GS_LPDDR4B_FB+GS_LPDDR_TEX+USE_QSYS_TOP (only the known Quartus-only EMIF_Qsys unresolved in iverilog).
profile sh3_lpddr_fb_640: fixtures bios/payload_sh3_s640; macros GS_SH3_LPDDR_FB + GS_SH3_LPDDR_FB_640 + GS_LPDDR_TEX. QSF verified (macros + fixtures applied; no stale SCHED/MULTITEX). NO FEEDER_STG_INIT_FILE (runtime-staged).

Copyright

sh3_s640_epochs.txt added to the exact-path ignore rule; all sh3_s640* fixtures + build FB dumps gitignored; only own code (TB, generator, host, compose) trackable.

Regression — strict tally (full `make run`)

make exit 0; completion marker === all testbenches complete === present.
272 / 272 run-list TBs → PASS verdict (the 7 "missing" are name-aliases; their _stub targets confirmed PASS).
0 ] FAIL verdicts (the 2 FAIL-pix hits are per-pixel diagnostic fields; both TBs verdict PASS, errors=0).
0 $fatal / assertion failures. The lone errors=128 is the pre-existing tb_gs_lpddr_scanout_lb internal diagnostic counter (unmodified by Ch357; TB verdicts PASS). The many "error" grep hits are benign iverilog lint ($error un-synthesizable).
Identical tally to the Ch356 regression → Ch357 introduced zero regressions.

Claim

Ch356 scheduler on a native 640×480 framebuffer with authentic screen coordinates. Accumulation 100% bit-for-bit on the full frame; exact 38400 scanout beats; FB/texture ranges disjoint. Fidelity ~92–94% (reciprocal floor, unchanged). Census Z usage next; no speculative Z.

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