thejayman77
ba74bbd5aa
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>
65 lines
2.8 KiB
Markdown
65 lines
2.8 KiB
Markdown
# Ch427 — complete authentic alpha family
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## Objective
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Replace Ch426's hand-selected 53-draw alpha subset with every captured PSMT8
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alpha-fan draw in the chronological post-process range, while retaining strict
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RTL and silicon equality and admitting the result only on measured PCSX2
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fidelity improvement.
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## Precision control
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Before expanding the family, a controlled replay increased the shared
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reciprocal table from 11 to 13 bits. It changed 32,173 output pixels, but the
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mapped PCSX2 score was effectively flat: MAE 20.0716 / RMSE 28.9629 versus
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20.0713 / 28.9639 at 11 bits. The extra table cost therefore had no useful
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fidelity return and was rejected.
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## Complete family and epoch packing
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The captured interval contains 93 authentic PSMT8 alpha-fan draws, not the 53
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draws selected by the older Ch405 fixture. The omitted 40 include captured
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anchor alpha as high as `0x11`; they are real atmospheric contributions, not
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transparent no-ops.
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An initial one-triangle expansion produced 408 alpha epochs. It also exposed
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a valid marker corner: a fully Z-rejected epoch emits no color write, leaving
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the host's stale `frame_drained` observation high and preventing a new drain
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edge. The acceptance gate was not weakened. Instead, the same ordered draws
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were safely capacity-packed into 129 productive alpha epochs, with maximum
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coverage 14,497 fragments. `zsrt139f28` is Ch424's 125 scene epochs, the 20
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captured CT32 darken epochs, and those 129 alpha epochs: 274 total.
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## Production RTL acceptance
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The complete replay passed:
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- 1,325,665 fragments fed; 1,306,030 passed;
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- 274 markers and drains;
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- zero fragment drops, color overflows, and AXI errors;
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- Z mismatch 0/307,200 and color mismatch 0/245,423;
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- framebuffer SHA-256
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`2aaaabfbe4054b6445458eb43dffb5bcb9d7989c3121875c64fcf0839478d976`.
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Against the PCSX2 reference using the accepted display mapping, the result is
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MAE 18.9384 / RMSE 27.6464. That is a material improvement over Ch426's
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20.0713 / 28.9639. The complete family changes 142,182 pixels relative to the
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53-draw subset and restores broad captured atmosphere without the former
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white-frame failure.
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## Silicon acceptance
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No new Quartus compile was required. The timing-clean Ch423 RBF
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(`17d1c1b49aac4d893ed56285cf0703bf375db2ee9f472ea36862cca376ae63fe`)
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ran all 274 epochs on the DE25. Every texture CRC, palette checksum, staged
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record count, ordered drain, and zero-drop gate passed; the host returned
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`rc=0` and enabled the HDMI line-buffer source.
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The board dumped all 307,200 words with 212,213 nonzero pixels, bounds
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`(0,0)..(511,479)`, sum32 `0x9c2fcd95`, and xor32 `0x6e7390f3`. Board and RTL
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framebuffer dumps are byte-identical and share the SHA-256 above. The accepted
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board image is preserved as
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`captures/gs/silenthill3/extracted/sh3_zsrt139f28_ch427_board.png`.
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Ch427 is accepted on silicon and is the current live HDMI baseline.
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