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feat(audio): implement nominal Direct Sound playback and FIFO DMA

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0xrsydn 2026-10-07 01:35:55 +07:00
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docs/research/emerald-reset.md
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@ -9,10 +9,11 @@ No ROM bytes, extracted code, or assets were added to the repository.
## General correction
The core now provides a bounded [disabled sound](../hardware/audio.md) and [disconnected serial](../hardware/serial.md) initialization model.
The reset correction introduced bounded sound and [disconnected serial](../hardware/serial.md) initialization models.
The [sound model](../hardware/audio.md) now also supports timer-driven Direct Sound and bounded FIFO DMA.
The BIOS performs reset through original ARM stores against that model.
Bit 5 selects general-purpose input pins and clears supported serial reset registers.
Bit 6 disables sound, clears mixing configuration and accessible wave RAM, and sets the functional bias default.
Bit 6 disables sound, resets FIFO queues, clears mixing configuration and accessible wave RAM, and sets the functional bias default.
The low halfword of SIODATA32 is cleared unconditionally, matching the documented BIOS side effect.
This is not a game-specific bypass. Original ARM and Thumb callers exercise selected flags and the all-device request.
@ -28,13 +29,18 @@ direnv exec . cargo run --locked --release -- --rom roms/pokemon-emerald.gba --s
direnv exec . cargo run --locked --release -- --rom roms/pokemon-emerald.gba --window --frames 120
```
Both runs now pass the BIOS reset and stop at the game's sound activation write:
The earlier reset-only implementation stopped at master sound enable (`0x04000084`, PC `0x082e0518`).
After the Direct Sound increment, both runs pass that write and stop at an enabled PSG channel 1 trigger:
```text
PC=0x082e0518
unsupported sound master enable (audio engine not implemented): write 0x8f at 0x04000084
Steps: 321159; instructions: 320647; IRQ entries: 0; DMA units: 512; HALT idle: 0
Nominal cycles: 1038738
PC=0x082e03bc
unsupported PSG channel trigger (synthesis not implemented): write 0x80 at 0x04000065
```
The native run captures three startup frames. Direct Sound behavior is validated by original tests, not by audible game output.
The native run captures startup frames before this diagnostic. These are not evidence of a working title screen or gameplay.
The window run does not reach its requested frame limit and correctly exits with failure.
Terminal execution is also diagnostic, not a compatibility pass.
@ -46,9 +52,10 @@ Workspace debug/release tests, strict Clippy, public ARM/Thumb/memory/BIOS check
Native ROM-window tests and graphics smoke modes pass on Darwin arm64.
The pinned Pong debug/release reports match.
The next observed startup requirement is active audio-device behavior, starting at SOUNDCNT_X master enable.
Implement channel/FIFO clocks, state, DMA requests, and an output interface before claiming sound support.
Do not make enable succeed solely to suppress this diagnostic.
The next observed startup requirement is PSG channel playback, beginning with pulse channel 1.
Direct Sound now has FIFO clocks, nominal DMA requests, and an instantaneous digital-level inspection interface.
A continuous sample stream and desktop output are still missing. Do not treat digital-level tests as audible-game validation.
Do not suppress the PSG trigger diagnostic without implementing the requested device behavior.
Cartridge saves remain a separate required feature. SRAM alone will not support Emerald's Flash save protocol.
Hardware and emulator references are recorded in the linked subsystem documents.