[APU/Linux] Implement cross platform audio using SDL2 library.

8 files changed, 329 insertions, 1 deletions

diff --git a/premake5.lua b/premake5.lua
index e5158612d..91b8c2342 100644
--- a/premake5.lua
+++ b/premake5.lua
@@ -229,6 +229,7 @@ solution("xenia")
   include("src/xenia/app/discord")
   include("src/xenia/apu")
   include("src/xenia/apu/nop")
+  include("src/xenia/apu/sdl")
   include("src/xenia/base")
   include("src/xenia/cpu")
   include("src/xenia/cpu/backend/x64")
diff --git a/src/xenia/app/premake5.lua b/src/xenia/app/premake5.lua
index e5fd4ba8f..a385245ac 100644
--- a/src/xenia/app/premake5.lua
+++ b/src/xenia/app/premake5.lua
@@ -23,6 +23,7 @@ project("xenia-app")
     "xenia-app-discord",
     "xenia-apu",
     "xenia-apu-nop",
+    "xenia-apu-sdl",
     "xenia-base",
     "xenia-core",
     "xenia-cpu",
diff --git a/src/xenia/app/xenia_main.cc b/src/xenia/app/xenia_main.cc
index bcd76d553..623744651 100644
--- a/src/xenia/app/xenia_main.cc
+++ b/src/xenia/app/xenia_main.cc
@@ -23,6 +23,7 @@
 
 // Available audio systems:
 #include "xenia/apu/nop/nop_audio_system.h"
+#include "xenia/apu/sdl/sdl_audio_system.h"
 #if XE_PLATFORM_WIN32
 #include "xenia/apu/xaudio2/xaudio2_audio_system.h"
 #endif  // XE_PLATFORM_WIN32
@@ -45,7 +46,7 @@
 
 #include "third_party/xbyak/xbyak/xbyak_util.h"
 
-DEFINE_string(apu, "any", "Audio system. Use: [any, nop, xaudio2]", "APU");
+DEFINE_string(apu, "any", "Audio system. Use: [any, nop, sdl, xaudio2]", "APU");
 DEFINE_string(gpu, "any",
               "Graphics system. Use: [any, d3d12, vulkan, vk, null]", "GPU");
 DEFINE_string(hid, "any", "Input system. Use: [any, nop, sdl, winkey, xinput]",
@@ -149,6 +150,7 @@ std::unique_ptr<apu::AudioSystem> CreateAudioSystem(cpu::Processor* processor) {
 #if XE_PLATFORM_WIN32
   factory.Add<apu::xaudio2::XAudio2AudioSystem>("xaudio2");
 #endif  // XE_PLATFORM_WIN32
+  factory.Add<apu::sdl::SDLAudioSystem>("sdl");
   factory.Add<apu::nop::NopAudioSystem>("nop");
   return factory.Create(cvars::apu, processor);
 }
diff --git a/src/xenia/apu/sdl/premake5.lua b/src/xenia/apu/sdl/premake5.lua
new file mode 100644
index 000000000..883d8b0c6
--- /dev/null
+++ b/src/xenia/apu/sdl/premake5.lua
@@ -0,0 +1,29 @@
+project_root = "../../../.."
+include(project_root.."/tools/build")
+
+group("src")
+project("xenia-apu-sdl")
+  uuid("153b4e8b-813a-40e6-9366-4b51abc73c45")
+  kind("StaticLib")
+  language("C++")
+  links({
+    "xenia-base",
+    "xenia-apu",
+    "SDL2",
+  })
+  defines({
+  })
+  local_platform_files()
+
+  filter("platforms:Windows")
+    -- On linux we build against the system version (libsdl2-dev)
+    includedirs({
+      project_root.."/third_party/SDL2-devel-VC/include/",
+    })
+    libdirs({
+      project_root.."/third_party/SDL2-devel-VC/lib/x64/",
+    })
+    -- Copy the dll to the output folder
+    postbuildcommands({
+      "{COPY} %{prj.basedir}/"..project_root.."/third_party/SDL2-devel-VC/lib/x64/SDL2.dll %{cfg.targetdir}",
+    })
diff --git a/src/xenia/apu/sdl/sdl_audio_driver.cc b/src/xenia/apu/sdl/sdl_audio_driver.cc
new file mode 100644
index 000000000..12a7da021
--- /dev/null
+++ b/src/xenia/apu/sdl/sdl_audio_driver.cc
@@ -0,0 +1,147 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2020 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include "xenia/apu/sdl/sdl_audio_driver.h"
+
+#include <array>
+
+#include "xenia/apu/apu_flags.h"
+#include "xenia/base/logging.h"
+#if XE_PLATFORM_WIN32
+#include "xenia/base/platform_win.h"
+#endif  // XE_PLATFORM_WIN32
+
+namespace xe {
+namespace apu {
+namespace sdl {
+
+SDLAudioDriver::SDLAudioDriver(Memory* memory,
+                               xe::threading::Semaphore* semaphore)
+    : AudioDriver(memory), semaphore_(semaphore) {}
+
+SDLAudioDriver::~SDLAudioDriver() {
+  assert_true(frames_queued_.empty());
+  assert_true(frames_unused_.empty());
+};
+
+bool SDLAudioDriver::Initialize() {
+  // With msvc delayed loading, exceptions are used to determine dll presence.
+#if XE_PLATFORM_WIN32
+  __try {
+#endif  // XE_PLATFORM_WIN32
+    SDL_version ver = {};
+    SDL_GetVersion(&ver);
+    if ((ver.major < 2) ||
+        (ver.major == 2 && ver.minor == 0 && ver.patch < 8)) {
+      XELOGW(
+          "SDL library version %d.%d.%d is outdated. "
+          "You may experience choppy audio.",
+          ver.major, ver.minor, ver.patch);
+    }
+#if XE_PLATFORM_WIN32
+  } __except (EXCEPTION_EXECUTE_HANDLER) {
+    return false;
+  }
+#endif  // XE_PLATFORM_WIN32
+
+  if (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0) {
+    return false;
+  }
+  sdl_initialized_ = true;
+
+  SDL_AudioCallback audio_callback = [](void* userdata, Uint8* stream,
+                                        int len) -> void {
+    assert_true(len == frame_size_);
+    const auto driver = static_cast<SDLAudioDriver*>(userdata);
+
+    std::unique_lock<std::mutex> guard(driver->frames_mutex_);
+    if (driver->frames_queued_.empty()) {
+      memset(stream, 0, len);
+    } else {
+      auto buffer = driver->frames_queued_.front();
+      driver->frames_queued_.pop();
+      if (cvars::mute) {
+        memset(stream, 0, len);
+      } else {
+        memcpy(stream, buffer, len);
+      }
+      driver->frames_unused_.push(buffer);
+
+      auto ret = driver->semaphore_->Release(1, nullptr);
+      assert_true(ret);
+    }
+  };
+
+  SDL_AudioSpec wanted_spec = {};
+  wanted_spec.freq = frame_frequency_;
+  wanted_spec.format = AUDIO_F32;
+  wanted_spec.channels = frame_channels_;
+  wanted_spec.samples = channel_samples_;
+  wanted_spec.callback = audio_callback;
+  wanted_spec.userdata = this;
+  sdl_device_id_ = SDL_OpenAudioDevice(nullptr, 0, &wanted_spec, nullptr, 0);
+  if (sdl_device_id_ <= 0) {
+    XELOGE("SDL_OpenAudioDevice() failed.");
+    return false;
+  }
+  SDL_PauseAudioDevice(sdl_device_id_, 0);
+
+  return true;
+}
+
+void SDLAudioDriver::SubmitFrame(uint32_t frame_ptr) {
+  const auto input_frame = memory_->TranslateVirtual<float*>(frame_ptr);
+  float* output_frame;
+  {
+    std::unique_lock<std::mutex> guard(frames_mutex_);
+    if (frames_unused_.empty()) {
+      output_frame = new float[frame_samples_];
+    } else {
+      output_frame = frames_unused_.top();
+      frames_unused_.pop();
+    }
+  }
+
+  // interleave the data
+  for (size_t index = 0, o = 0; index < channel_samples_; ++index) {
+    for (size_t channel = 0, table = 0; channel < frame_channels_;
+         ++channel, table += channel_samples_) {
+      output_frame[o++] = xe::byte_swap(input_frame[table + index]);
+    }
+  }
+
+  {
+    std::unique_lock<std::mutex> guard(frames_mutex_);
+    frames_queued_.push(output_frame);
+  }
+}
+
+void SDLAudioDriver::Shutdown() {
+  if (sdl_device_id_ > 0) {
+    SDL_CloseAudioDevice(sdl_device_id_);
+    sdl_device_id_ = -1;
+  }
+  if (sdl_initialized_) {
+    SDL_QuitSubSystem(SDL_INIT_AUDIO);
+    sdl_initialized_ = false;
+  }
+  std::unique_lock<std::mutex> guard(frames_mutex_);
+  while (!frames_unused_.empty()) {
+    delete[] frames_unused_.top();
+    frames_unused_.pop();
+  };
+  while (!frames_queued_.empty()) {
+    delete[] frames_queued_.front();
+    frames_queued_.pop();
+  };
+}
+
+}  // namespace sdl
+}  // namespace apu
+}  // namespace xe
diff --git a/src/xenia/apu/sdl/sdl_audio_driver.h b/src/xenia/apu/sdl/sdl_audio_driver.h
new file mode 100644
index 000000000..404ceaa6a
--- /dev/null
+++ b/src/xenia/apu/sdl/sdl_audio_driver.h
@@ -0,0 +1,54 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2020 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_APU_SDL_SDL_AUDIO_DRIVER_H_
+#define XENIA_APU_SDL_SDL_AUDIO_DRIVER_H_
+#include <SDL2/SDL.h>
+
+#include <mutex>
+#include <queue>
+#include <stack>
+
+#include "xenia/apu/audio_driver.h"
+#include "xenia/base/threading.h"
+
+namespace xe {
+namespace apu {
+namespace sdl {
+
+class SDLAudioDriver : public AudioDriver {
+ public:
+  SDLAudioDriver(Memory* memory, xe::threading::Semaphore* semaphore);
+  ~SDLAudioDriver() override;
+
+  bool Initialize();
+  void SubmitFrame(uint32_t frame_ptr) override;
+  void Shutdown();
+
+ protected:
+  xe::threading::Semaphore* semaphore_ = nullptr;
+
+  SDL_AudioDeviceID sdl_device_id_ = -1;
+  bool sdl_initialized_ = false;
+
+  static const uint32_t frame_frequency_ = 48000;
+  static const uint32_t frame_channels_ = 6;
+  static const uint32_t channel_samples_ = 256;
+  static const uint32_t frame_samples_ = frame_channels_ * channel_samples_;
+  static const uint32_t frame_size_ = sizeof(float) * frame_samples_;
+  std::queue<float*> frames_queued_ = {};
+  std::stack<float*> frames_unused_ = {};
+  std::mutex frames_mutex_ = {};
+};
+
+}  // namespace sdl
+}  // namespace apu
+}  // namespace xe
+
+#endif  // XENIA_APU_SDL_SDL_AUDIO_DRIVER_H_
diff --git a/src/xenia/apu/sdl/sdl_audio_system.cc b/src/xenia/apu/sdl/sdl_audio_system.cc
new file mode 100644
index 000000000..12a4c4616
--- /dev/null
+++ b/src/xenia/apu/sdl/sdl_audio_system.cc
@@ -0,0 +1,54 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2020 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include "xenia/apu/sdl/sdl_audio_system.h"
+
+#include "xenia/apu/apu_flags.h"
+#include "xenia/apu/sdl/sdl_audio_driver.h"
+
+namespace xe {
+namespace apu {
+namespace sdl {
+
+std::unique_ptr<AudioSystem> SDLAudioSystem::Create(cpu::Processor* processor) {
+  return std::make_unique<SDLAudioSystem>(processor);
+}
+
+SDLAudioSystem::SDLAudioSystem(cpu::Processor* processor)
+    : AudioSystem(processor) {}
+
+SDLAudioSystem::~SDLAudioSystem() {}
+
+void SDLAudioSystem::Initialize() { AudioSystem::Initialize(); }
+
+X_STATUS SDLAudioSystem::CreateDriver(size_t index,
+                                      xe::threading::Semaphore* semaphore,
+                                      AudioDriver** out_driver) {
+  assert_not_null(out_driver);
+  auto driver = new SDLAudioDriver(memory_, semaphore);
+  if (!driver->Initialize()) {
+    driver->Shutdown();
+    return X_STATUS_UNSUCCESSFUL;
+  }
+
+  *out_driver = driver;
+  return X_STATUS_SUCCESS;
+}
+
+void SDLAudioSystem::DestroyDriver(AudioDriver* driver) {
+  assert_not_null(driver);
+  auto sdldriver = dynamic_cast<SDLAudioDriver*>(driver);
+  assert_not_null(sdldriver);
+  sdldriver->Shutdown();
+  delete sdldriver;
+}
+
+}  // namespace sdl
+}  // namespace apu
+}  // namespace xe
diff --git a/src/xenia/apu/sdl/sdl_audio_system.h b/src/xenia/apu/sdl/sdl_audio_system.h
new file mode 100644
index 000000000..9f9d3108f
--- /dev/null
+++ b/src/xenia/apu/sdl/sdl_audio_system.h
@@ -0,0 +1,40 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2020 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_APU_SDL_SDL_AUDIO_SYSTEM_H_
+#define XENIA_APU_SDL_SDL_AUDIO_SYSTEM_H_
+
+#include "xenia/apu/audio_system.h"
+
+namespace xe {
+namespace apu {
+namespace sdl {
+
+class SDLAudioSystem : public AudioSystem {
+ public:
+  explicit SDLAudioSystem(cpu::Processor* processor);
+  ~SDLAudioSystem() override;
+
+  static bool IsAvailable() { return true; }
+
+  static std::unique_ptr<AudioSystem> Create(cpu::Processor* processor);
+
+  X_RESULT CreateDriver(size_t index, xe::threading::Semaphore* semaphore,
+                        AudioDriver** out_driver) override;
+  void DestroyDriver(AudioDriver* driver) override;
+
+ protected:
+  void Initialize() override;
+};
+
+}  // namespace sdl
+}  // namespace apu
+}  // namespace xe
+
+#endif  // XENIA_APU_SDL_SDL_AUDIO_SYSTEM_H_