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>
53 lines
2.5 KiB
Markdown
53 lines
2.5 KiB
Markdown
# Ch405 — authentic alpha-fan overlays (pre-fit gate)
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## Objective
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Add the 53 chronological PSMT8 alpha-fan draws at capture indices 196494
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through 198058 after the accepted 75-epoch Ch404 opaque composite. These are
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large translucent overlays using authentic `ZTE=1`, `GEQUAL`, `ZMSK=1`, and
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`PSMZ16S`: they test the accumulated depth buffer, blend on pass, and must not
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modify Z.
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## RTL change
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- Carry architectural `TEST.ZTE` and `ZBUF.ZMSK` alongside each perspective
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fragment through `gs_stub` and `top_psmct32_raster_demo_bram` into the
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existing external LPDDR Z/color ROP.
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- Replace the de25 wrapper's former `ZTE=1/ZMSK=0` constants with those
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sidebands.
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- Increase the production async request FIFO from 4,096 to 16,384 entries.
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The alpha writer preserves exact destination order and can be slower than
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the unthrottled raster producer, so the fixture bounds each epoch to one
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triangle. Measured worst-triangle occupancy is 12,953 entries, leaving
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3,431 entries of observed headroom.
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## Fixture
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- `zsrt139c3`: 212 one-triangle alpha epochs, preserving all 212 triangles
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expanded from the 53 authentic fan draws.
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- `zsrt139c4`: Ch403 base + Ch404 detail tail + Ch405 alpha tail, 287 epochs.
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- Authentic TEST/ZBUF header words are restored in the accepted base fixtures;
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their geometry, colors, textures, palettes, and record counts are unchanged.
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- Host/testbench epoch ceilings rise from 128 to 512.
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## Pre-fit evidence
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- The unbounded three-epoch diagnostic correctly failed closed at epoch 75:
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169,213 request drops and FIFO high-water 4,096/4,096. It is retained only
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as the measurement that justified bounded bursts.
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- Worst-tail three-epoch test (empty Z): 43,680 fed/passed, zero drops,
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high-water 12,953/16,384, exact color and Z, PASS.
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- Checkerboard-Z test: 43,680 fed, 21,839 passed, zero drops, high-water
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11,389/16,384, exact color, exact unchanged Z at all 307,200 pixels, PASS.
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- Full Ch404 baseline replay with authentic headers reached its exact accepted
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epoch-74 counts (667,279 fed / 351,074 passed) with zero drops before the
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intentionally unbounded diagnostic alpha epoch.
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- Host runner compiles cleanly; generated production assets total about 174 MiB.
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## Status
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Ready for owner Quartus 26.1 GUI compile. Do not deploy the prior
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`28659ebf...` RBF as Ch405; the new RBF must contain the 16K request FIFO and
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TEST/ZMSK sidebands. After a timing/resource-clean fit, deploy and run
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`zsrt139c4`, then compare the board framebuffer byte-for-byte with RTL.
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