Files

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thejayman77 dd75d78491 Fix signoff timing: remove dead bilinear clamp (comb loop) + relax gray skew 2.0->2.5ns

Two fixes for the failing STA (Codex-reviewed):
1. gs_texture_unit lerp8: remove the dead 0/255 clamp. For 8-bit taps and f in
   0..15, a+floor((b-a)*f/16) is always in [0,255], so the clamp never fired -
   but its comparators formed a 161-node combinational loop that failed
   design-clock setup by 42 ps (tap[0][11] -> tex_cache_sel_q). Functionally
   identical (tb_gs_texture_bilinear + texture TBs bit-identical PASS).
2. SDC: relax the u_zc_emit gray-code CDC max_skew 2.0 -> 2.5 ns. Post-fog
   placement pushed actual skew to 2.010 ns (fails 2.0 by ~10 ps). Real ceiling
   is the 3.225 ns EMIF period (one gray bit in flight); 2.5 clears the miss and
   stays well under it. Documented relax of a conservative round number.

Acceptance (owner fit): no comb-loop warning, no tap->tex_cache_sel_q path,
all setup + max_skew slacks >= 0.

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

2026-07-20 20:03:42 -04:00

clut_loader_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

clut_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

ee_gs_priv_bridge_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gif_image_xfer_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gif_packed_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gif_path_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_alpha_blend.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_async_fifo.sv

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

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

gs_grad_divider.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_lpddr_axi_master.sv

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

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

gs_lpddr_color_blend.sv

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

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

gs_lpddr_fb_writer.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_lpddr_map_pkg.sv

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

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

gs_lpddr_rd_arb.sv

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

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

gs_lpddr_rd_probe.sv

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

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

gs_lpddr_scanout_lb.sv

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

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

gs_lpddr_scanout.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_lpddr_wr_arb.sv

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

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

gs_lpddr_wr_probe.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_lpddr_z_rmw.sv

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

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

gs_lpddr_zc_emit.sv

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

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

gs_pcrtc_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_persp_uv.sv

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

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

gs_prim_list_feeder.sv

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

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

gs_reciprocal_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_stub.sv

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

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

gs_swizzle_psmct16_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_swizzle_psmct32_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_swizzle_psmt4_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_swizzle_psmt8_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_texel_addr.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_texture_cache.sv

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

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

gs_texture_unit.sv

Fix signoff timing: remove dead bilinear clamp (comb loop) + relax gray skew 2.0->2.5ns

2026-07-20 20:03:42 -04:00

gs_tile_ram.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_tile_reload.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

gs_z_flush_writer.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

README.md

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

vram_bram_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

vram_normalize_pkg.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

vram_stub.sv

Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

2026-06-29 20:10:50 -04:00

README.md

rtl/gif_gs

GIF path and Graphics Synthesizer logic. Matches docs/contracts/gif_gs.md.

Current contents

gs_stub.sv — GS shell with two architecturally distinct write ports (Ch75 namespace split):
- reg_wr_* — privileged-block writes (16-bit offset within 0x12000000). Latches BGCOLOR (offset 0x00E0) into bg_{r,g,b}; other offsets emit EV_MODE.
- gif_reg_* — GIF A+D register-number writes (8-bit reg# + 64-bit data). Decodes PRIM=0x00, RGBAQ=0x01, XYZF2=0x04, XYZ2=0x05, FRAME_1=0x4C, ZBUF_1=0x4E into per-register 64-bit latches; unknown reg numbers emit EV_MODE.
- No VRAM, no drawing yet — that is the next architectural step.
gif_path_stub.sv — Wave 2 minimal GIF packet logger; project-local single-qword register-write format. Used by tb_bgcolor_via_dma.
gif_packed_stub.sv — real PS2 GIFtag parser (Ch72-Ch75). Handles PACKED (FLG=0), REGLIST (FLG=1), IMAGE (FLG=2), DISABLE (FLG=3). The REAL_AD_REG_MAP parameter selects the A+D dispatch port:
- REAL_AD_REG_MAP=0 (default, back-compat) — drives gs_stub.reg_wr_* using a project-local 16-bit offset carried in in_data[79:64].
- REAL_AD_REG_MAP=1 — drives gs_stub.gif_reg_* using the real PS2 8-bit reg# carried in in_data[71:64]. Source-of-truth: PCSX2 GSRegs.h.

BGCOLOR reset value

At reset, bg_{r,g,b} default to 0x40 each (mid-grey) rather than black. Rationale: this makes "gs_stub reset but no BGCOLOR write yet" visually distinct from "video output disabled / black frame" in Milestone A. Override is a BGCOLOR write from the test harness.

Pitfall: namespace conflation

Ch74 conflated GIF A+D reg numbers with GS privileged-block offsets and mapped e.g. 0x14→PMODE@0x0000. That is fiction — those are separate namespaces. Ch75 split them. ZBUF_1 is 0x4E, not 0x4F (that's ZBUF_2). When adding a new GIF-context register, source the reg# from PCSX2 GSRegs.h, never from the privileged-block map.