[APU] Add ALSA apu on Linux

src/xenia/apu/alsa/alsa_audio_system.cc

@@ -0,0 +1,94 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2025. All rights reserved.                                       *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include "xenia/apu/alsa/alsa_audio_system.h"
+
+#include <alsa/asoundlib.h>
+
+#include "xenia/apu/alsa/alsa_audio_driver.h"
+#include "xenia/apu/apu_flags.h"
+#include "xenia/base/logging.h"
+
+namespace xe {
+namespace apu {
+namespace alsa {
+
+ALSAAudioSystem::ALSAAudioSystem(cpu::Processor* processor)
+    : AudioSystem(processor) {}
+
+ALSAAudioSystem::~ALSAAudioSystem() {}
+
+bool ALSAAudioSystem::IsAvailable() {
+  // Check if ALSA is available by trying to open a dummy PCM device
+  snd_pcm_t* pcm = nullptr;
+  int err =
+      snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
+  if (err >= 0 && pcm) {
+    snd_pcm_close(pcm);
+    return true;
+  }
+  return false;
+}
+
+void ALSAAudioSystem::Initialize() {}
+
+std::unique_ptr<AudioSystem> ALSAAudioSystem::Create(
+    cpu::Processor* processor) {
+  if (!IsAvailable()) {
+    XELOGE("ALSA is not available on this system");
+    return nullptr;
+  }
+  return std::make_unique<ALSAAudioSystem>(processor);
+}
+
+X_RESULT ALSAAudioSystem::CreateDriver(size_t index,
+                                       xe::threading::Semaphore* semaphore,
+                                       AudioDriver** out_driver) {
+  assert_not_null(out_driver);
+
+  XELOGI("ALSAAudioSystem::CreateDriver for client index {}", index);
+
+  // Create a new driver for each client
+  // ALSA's dmix plugin should handle mixing multiple streams
+  auto driver = new ALSAAudioDriver(semaphore);
+  if (!driver->Initialize()) {
+    XELOGE("Failed to initialize ALSA driver for client index {}", index);
+    delete driver;
+    *out_driver = nullptr;
+    return X_ERROR_NOT_FOUND;
+  }
+
+  *out_driver = driver;
+  XELOGI("Successfully created ALSA driver for client index {}", index);
+  return X_ERROR_SUCCESS;
+}
+
+AudioDriver* ALSAAudioSystem::CreateDriver(xe::threading::Semaphore* semaphore,
+                                           uint32_t frequency,
+                                           uint32_t channels,
+                                           bool need_format_conversion) {
+  auto driver = new ALSAAudioDriver(semaphore, frequency, channels,
+                                    need_format_conversion);
+  if (!driver->Initialize()) {
+    delete driver;
+    return nullptr;
+  }
+  return driver;
+}
+
+void ALSAAudioSystem::DestroyDriver(AudioDriver* driver) {
+  assert_not_null(driver);
+  ALSAAudioDriver* alsa_driver = static_cast<ALSAAudioDriver*>(driver);
+  alsa_driver->Shutdown();
+  delete alsa_driver;
+}
+
+}  // namespace alsa
+}  // namespace apu
+}  // namespace xe