dusk/src/duskdolphin/audio/audiostreamdolphin.c

/**
 * Copyright (c) 2026 Dominic Masters
 *
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "audiostreamdolphin.h"
#include "audio/audiostream.h"
#include "assert/assert.h"
#include "util/memory.h"
#include <ansndlib.h>
#include <ogc/cache.h>
#include <ogc/system.h>

errorret_t audioStreamDolphinInit(audiostream_t *stream) {
  assertNotNull(stream, "Stream cannot be NULL.");

  const s32 voiceId = ansnd_allocate_voice();
  if(voiceId < 0) {
    errorThrow(
      "Failed to allocate ansnd voice: %s", ansnd_get_error_string(voiceId)
    );
  }

  stream->platform.voiceId = voiceId;
  stream->platform.finished = false;

  errorOk();
}

errorret_t audioStreamDolphinDispose(audiostream_t *stream) {
  assertNotNull(stream, "Stream cannot be NULL.");

  ansnd_deallocate_voice((u32) stream->platform.voiceId);

  errorOk();
}

errorret_t audioStreamDolphinBuffer(audiostream_t *stream) {
  assertNotNull(stream, "Stream cannot be NULL.");

  const size_t frameSize = stream->pcm.channels * sizeof(int16_t);

  float_t leftFactor, rightFactor;
  audioStreamGetPanFactors(stream, &leftFactor, &rightFactor);

  const float_t baseVolume = (float_t) stream->volume / 255.0f;

  stream->platform.finished = false;

  ansnd_pcm_voice_config_t config;
  memoryZero(&config, sizeof(ansnd_pcm_voice_config_t));
  config.samplerate = stream->pcm.sampleRate;
  config.format = ANSND_VOICE_PCM_FORMAT_SIGNED_16_PCM;
  config.channels = stream->pcm.channels;
  config.pitch = 1.0f;
  config.left_volume = baseVolume * leftFactor;
  config.right_volume = baseVolume * rightFactor;
  // The DSP DMAs frame_data_ptr directly out of main memory, bypassing the
  // CPU cache, and rejects any pointer in cached virtual address space
  // (0x8xxxxxxx.. - checked as "negative" internally, returned as
  // ANSND_ERROR_INVALID_MEMORY) - it needs the physical address instead.
  // Flush first so the DMA sees what the CPU actually wrote, not stale
  // memory contents.
  DCFlushRange(stream->data, stream->dataSize);
  config.frame_data_ptr = MEM_VIRTUAL_TO_PHYSICAL(stream->data);
  config.frame_count = (u32) (stream->dataSize / frameSize);
  config.start_offset = (u32) stream->startFrame;
  stream->startFrame = 0;
  stream->seeking = false;
  config.voice_callback = audioStreamDolphinVoiceCallback;
  config.stream_callback = NULL; // single-buffer playback
  config.user_pointer = stream;

  // Loop entirely in hardware rather than mirroring PSP/Linux's
  // detect-finished-then-restart-from-software approach: ansnd's DSP mixer
  // wraps loop_end_offset back to loop_start_offset on its own, so there's
  // no restart latency to create a gap in the first place (unlike a
  // software restart, which always costs at least a little).
  //
  // Trade-off: onLoop never fires for a Dolphin voice looping this way -
  // there's no ANSND_VOICE_STATE for "wrapped", only state transitions like
  // FINISHED/STOPPED, which a looping voice never reaches. And unlike
  // PSP's per-restart tail fade, the DSP does no smoothing at the wrap
  // point - it requires loopStart's frame to already flow cleanly into
  // loopTo's (true today only because the shared 441Hz test tone was
  // deliberately chosen to divide evenly into the sample rate).
  if(stream->state & AUDIO_STREAM_STATE_LOOPING) {
    config.loop_start_offset = (u32) (stream->loopTo * stream->pcm.sampleRate);
    config.loop_end_offset = stream->loopStart >= 0
      ? (u32) (stream->loopStart * stream->pcm.sampleRate) - 1
      : config.frame_count - 1;
  }

  s32 result = ansnd_configure_pcm_voice((u32) stream->platform.voiceId, &config);
  if(result != ANSND_ERROR_OK) {
    errorThrow(
      "Failed to configure ansnd voice: %s", ansnd_get_error_string(result)
    );
  }

  result = ansnd_start_voice((u32) stream->platform.voiceId);
  if(result != ANSND_ERROR_OK) {
    errorThrow(
      "Failed to start ansnd voice: %s", ansnd_get_error_string(result)
    );
  }

  errorOk();
}

bool_t audioStreamDolphinIsFinished(audiostream_t *stream) {
  assertNotNull(stream, "Stream cannot be NULL.");

  return stream->platform.finished;
}

void audioStreamDolphinVoiceCallback(void *userPointer, int32_t voiceState) {
  audiostream_t *stream = (audiostream_t *) userPointer;

  if(
    voiceState == ANSND_VOICE_STATE_FINISHED ||
    voiceState == ANSND_VOICE_STATE_STOPPED ||
    voiceState == ANSND_VOICE_STATE_ERROR
  ) {
    stream->platform.finished = true;
  }
}