Files
retroDE_ps2/rtl/gif_gs
thejayman77 27dfd0b0cf Ch443: combined timing repair for both Ch442 setup families
Ch442's fit exposed two failing setup families (plus a stale max-skew).
Attack both structurally; no reseeding.

Family 1 - AWREADY -> Z-FSM (-0.410): gen_p2c_ff[23] (EMIF AWREADY)
reached u_zc_emit|u_z's S_SFLUSH_AW/S_FILL_R next-state combinationally.
Ch441 registered only the W channel; add the AW twin:
- new gs_axi_aw_regbuf (one-entry fully-registered AW buffer), inserted
  in zc_emit between u_z's AW output and the arbiter s2 AW port. The FSM
  now sees registered occupancy, never EMIF's combinational AWREADY.

Family 2 - texcache drain_idx_q -> tex_mem (-0.370, x7): a single index
fanned across the whole 65536x32, 128-M20K macro. Split by WIDTH into
four 65536x8 banks, each with its own (* preserve, dont_merge *) write-
address launch register; write the four byte lanes together in F_WRITE;
reconstruct the sample word by concatenating four registered read bytes.
Selector structure and 1-cycle read latency unchanged; total M20Ks
unchanged (4x32 == 128); fill_crc still sums the full 32-bit word.

Max-skew: relax ONLY the Ch357 tile-write CDC set_max_skew 2.0 -> 2.5
(quasi-static bundle, >=2 dclk stability window); retain set_net_delay
2.0 (the real arrival bound). SDC comment updated.

Tests: new tb_gs_axi_aw_regbuf (AW scoreboard: exactly-once/order/no-
combinational-AWREADY-bypass/stable-while-stalled); tb_gs_texture_cache
strengthened to distinct-per-byte-bank data + per-bank + full-word
checks. All pass: aw/w regbuf, texture_cache, texture_psmt8_clut,
scanout_diag, ps2_hps_bridge, and the complete f52 replay BYTE-IDENTICAL
(Z 0/307200, COLOR 0/245760).

No Quartus, board, or push from here. Ready for one owner GUI fit.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-22 11:19:09 -04:00
..

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.