Add audio subsystem skeleton with a working Linux PCM playback path

Cross-platform audiostream/audio API with per-platform hooks for PSP/Dolphin/Linux. Linux is fully wired end-to-end through SDL2 (device open, volume-mixed queueing, finish detection via SDL_GetQueuedAudioSize) and verified playing a generated test tone in engine.c. PSP and Dolphin hooks are stubbed for now.
2026-08-31 10:24:02 -05:00
parent fcf0de72af
commit 8ea370a1d1
31 changed files with 1022 additions and 1 deletions
@@ -0,0 +1,67 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "audiostreamlinux.h"
+#include "audio/audiostream.h"
+#include "assert/assert.h"
+#include "util/memory.h"
+
+errorret_t audioStreamLinuxInit(audiostream_t *stream) {
+  assertNotNull(stream, "Stream cannot be NULL.");
+
+  SDL_AudioSpec desired;
+  memoryZero(&desired, sizeof(SDL_AudioSpec));
+  desired.freq = (int) stream->pcm.sampleRate;
+  desired.format = AUDIO_S16SYS;
+  desired.channels = stream->pcm.channels;
+  desired.samples = 4096;
+
+  stream->platform.device = SDL_OpenAudioDevice(NULL, 0, &desired, NULL, 0);
+  if(stream->platform.device == 0) {
+    errorThrow("Failed to open SDL2 audio device: %s", SDL_GetError());
+  }
+
+  errorOk();
+}
+
+errorret_t audioStreamLinuxDispose(audiostream_t *stream) {
+  assertNotNull(stream, "Stream cannot be NULL.");
+
+  SDL_CloseAudioDevice(stream->platform.device);
+
+  errorOk();
+}
+
+errorret_t audioStreamLinuxBuffer(audiostream_t *stream) {
+  assertNotNull(stream, "Stream cannot be NULL.");
+
+  uint8_t *mixed = memoryAllocate(stream->dataSize);
+  memoryZero(mixed, stream->dataSize);
+  SDL_MixAudioFormat(
+    mixed, stream->data, AUDIO_S16SYS, (Uint32) stream->dataSize,
+    (stream->volume * SDL_MIX_MAXVOLUME) / 0xFF
+  );
+
+  int queued = SDL_QueueAudio(
+    stream->platform.device, mixed, (Uint32) stream->dataSize
+  );
+  memoryFree(mixed);
+
+  if(queued != 0) {
+    errorThrow("Failed to queue SDL2 audio data: %s", SDL_GetError());
+  }
+
+  SDL_PauseAudioDevice(stream->platform.device, 0);
+
+  errorOk();
+}
+
+bool_t audioStreamLinuxIsFinished(audiostream_t *stream) {
+  assertNotNull(stream, "Stream cannot be NULL.");
+
+  return SDL_GetQueuedAudioSize(stream->platform.device) == 0;
+}