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Video platform service (SNES backend): commands for PPU registers, VRAM/CGRAM/OAM uploads, HDMA tables #33

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opened 2026-10-29 20:36:27 +00:00 by Gatchan · 2 comments

Gatchan commented

2026-10-29 20:36:27 +00:00

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Brief §5 (platform services, "commands, not diffs") and §7.4 (no PPU/DMA register number in core/game). Needed before porting field routines that write PPU registers or start DMA (TfrObjGfxSub, InitMaskHDMAData, UpdateScrollHDMA, UpdateFixedColor, TfrBGAnimGfx, SetTopSpriteMSB...).

core/platform/video.h: operations named for what they do (upload tiles/tilemap/palette/OAM, set scroll, layer/window/colour-math state, HDMA channel tables, brightness/forced blank), game-facing types.
SNES backend in core/hw/: performs exactly the register writes and DMA transfers the original does (same order and values), so per-call shadow keeps comparing VRAM/CGRAM/OAM/PPU registers byte for byte.
Shadow comparison extended to PPU registers and DMA/HDMA channel registers where needed.
Port one hardware-touching field leaf with it as proof (e.g. SetTopSpriteMSB or UpdateFixedColor), shadow 0 mismatch US+JP.

Brief §5 (platform services, "commands, not diffs") and §7.4 (no PPU/DMA register number in core/game). Needed before porting field routines that write PPU registers or start DMA (TfrObjGfxSub, InitMaskHDMAData, UpdateScrollHDMA, UpdateFixedColor, TfrBGAnimGfx, SetTopSpriteMSB...). 1. `core/platform/video.h`: operations named for what they do (upload tiles/tilemap/palette/OAM, set scroll, layer/window/colour-math state, HDMA channel tables, brightness/forced blank), game-facing types. 2. SNES backend in `core/hw/`: performs exactly the register writes and DMA transfers the original does (same order and values), so per-call shadow keeps comparing VRAM/CGRAM/OAM/PPU registers byte for byte. 3. Shadow comparison extended to PPU registers and DMA/HDMA channel registers where needed. 4. Port one hardware-touching field leaf with it as proof (e.g. SetTopSpriteMSB or UpdateFixedColor), shadow 0 mismatch US+JP.

Gatchan added this to the Phase 2 - field ports milestone

2026-10-29 20:36:27 +00:00

Gatchan added the

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2026-10-29 20:36:27 +00:00

Gatchan referenced this issue

2026-10-29 23:55:37 +00:00

Field ports batch 1: timers, scroll, object frame and map position, party input #35

Gatchan referenced this issue

2026-11-03 07:27:28 +00:00

Field ports batch 1: WRAM-only leaves (timers, object order, scroll, object frames) #32

Gatchan commented

2026-11-03 07:28:10 +00:00

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Starting now (branch video-service), after #32. Order: platform video API, SNES backend reproducing the exact writes, shadow extended to PPU/DMA state, one hardware-touching field leaf as proof.

Starting now (branch `video-service`), after #32. Order: platform video API, SNES backend reproducing the exact writes, shadow extended to PPU/DMA state, one hardware-touching field leaf as proof.

Gatchan referenced this issue

2026-11-03 07:50:02 +00:00

LakeSnes: picture brightness is a global shared by every machine and not saved in savestates #47

Gatchan referenced this issue from a commit

2026-11-03 10:23:13 +00:00

state: hardware buffers get a pointer accessor; sprite_table and field_palettes buffers, fade direction fixed, fade_out_step scratch (refs #33)

Gatchan referenced this issue from a commit

2026-11-03 10:23:13 +00:00

hw: video service with SNES backend (brightness, color and sprite table uploads, field DMA style) (refs #33)

Gatchan referenced this issue from a commit

2026-11-03 10:23:13 +00:00

verify: shadow compares PPU and DMA channel registers for ports that write them; mismatches name the word, color or member (refs #33)

Gatchan referenced this issue from a commit

2026-11-03 10:23:13 +00:00

port: field UpdateBrightness, TfrPal, TfrSprites through the video service (shadow 5 routes: 0 mismatch 0 fallback US 74 738 calls x3, JP 68 636 x3) (refs #33)

Gatchan referenced this issue from a commit

2026-11-03 10:23:14 +00:00

refactor: upload style record covers every per-module choice; shadow reports undeclared hardware writes and unreachable upload sources; video contracts in the header (review of #33)

Gatchan referenced this issue from a commit

2026-11-03 10:23:14 +00:00

docs: field vblank video ports evidence (shadow 5 routes and fuzz US/JP, 0 mismatch 0 fallback) (refs #33)

Gatchan referenced this issue from a pull request that will close it,

2026-11-03 14:04:55 +00:00

Video service (SNES backend) and field vblank video ports #48

Gatchan closed this issue

2026-11-03 14:05:16 +00:00

Gatchan commented

2026-11-03 14:05:17 +00:00

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Done in PR (merged). Evidence (release build, routes = the five committed movies, all ports in shadow):

New ports field/UpdateBrightness, field/TfrPal, field/TfrSprites: shadow 0 mismatch, 0 skipped, 0 fallback; US 74 738 calls each, JP 68 636 each. The shadow now also compares PPU and DMA channel registers for these ports.
Earlier field ports: counts identical to docs/ports.md with the extended comparison.
Fuzz (fades incl. wrap-around, random palettes and sprite tables): US 8 628/8 628, JP 7 937/7 937, 0 mismatch. A recheck after the review fixes (2 routes + fuzz 40, US+JP) also gave 0 mismatch.
Original instructions executed: UpdateBrightness 30/30, TfrSprites 16/16, TfrPal 16/16 (US and JP).
Negative tests: a wrong DMA control byte is reported as DMA channel 0 indirect byte 0: 01/00; an undeclared PPU write is reported as writes PPU registers not declared PORT_WRITES_PPU.
ctest: release 61/61 incl. route_ports_on 5/5 US+JP (10 748 s); debug and clang -LE slow 24/24; 0 warnings.
Independent readability review: merge after must-fix. Applied (0649296): the style record covers every per-module choice, undeclared hardware writes and unreachable upload sources are reported, video contracts moved to the header; plus casts, the field_base_palettes rename and the JP check on rSpritesHi.

Done in PR (merged). Evidence (release build, routes = the five committed movies, all ports in shadow): - New ports `field/UpdateBrightness`, `field/TfrPal`, `field/TfrSprites`: shadow 0 mismatch, 0 skipped, 0 fallback; US 74 738 calls each, JP 68 636 each. The shadow now also compares PPU and DMA channel registers for these ports. - Earlier field ports: counts identical to docs/ports.md with the extended comparison. - Fuzz (fades incl. wrap-around, random palettes and sprite tables): US 8 628/8 628, JP 7 937/7 937, 0 mismatch. A recheck after the review fixes (2 routes + fuzz 40, US+JP) also gave 0 mismatch. - Original instructions executed: UpdateBrightness 30/30, TfrSprites 16/16, TfrPal 16/16 (US and JP). - Negative tests: a wrong DMA control byte is reported as `DMA channel 0 indirect byte 0: 01/00`; an undeclared PPU write is reported as `writes PPU registers not declared PORT_WRITES_PPU`. - ctest: release 61/61 incl. route_ports_on 5/5 US+JP (10 748 s); debug and clang -LE slow 24/24; 0 warnings. - Independent readability review: merge after must-fix. Applied (0649296): the style record covers every per-module choice, undeclared hardware writes and unreachable upload sources are reported, video contracts moved to the header; plus casts, the `field_base_palettes` rename and the JP check on rSpritesHi.

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Gatchan/FF6Portage#33

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