libretro: play speaker audio (with some glitches).

Signed-off-by: Andrea Odetti <mariofutire@gmail.com>

linux.md

@@ -23,6 +23,7 @@ There are 4 projects
 * applen: a frontend based on ncurses
 * qapple: Qt frontend
 * sa2: SDL2 frontend
+* libra2: a libretro core
 
 The libapple interface is a *link time* interface: some functions are not defined and must be provided in order to properly link
 the application. These functions are listed in [interface.h](source/linux/interface.h).
@@ -107,6 +108,8 @@ In order to have a better experience with the keyboard, one should probably enab
 
 Video works, but the vertical flip is done in software.
 
+Audio (speaker) works with some glitches.
+
 Must be manually configured:
 ``cmake -DLIBRETRO_PATH=/path/to/libretro-common``
 

source/frontends/libretro/CMakeLists.txt

@@ -15,6 +15,7 @@ if (EXISTS ${LIBRETRO_PATH}/include/libretro.h)
     joypadbase.cpp
     joypad.cpp
     analog.cpp
+    rdirectsound.cpp
     )
 
   target_include_directories(ra2 PRIVATE

source/frontends/libretro/libretro.cpp

@@ -4,6 +4,7 @@
 
 #include "StdAfx.h"
 #include "Frame.h"
+#include "Common.h"
 
 #include "linux/version.h"
 #include "linux/paddle.h"
@@ -12,6 +13,7 @@
 #include "frontends/libretro/environment.h"
 #include "frontends/libretro/joypad.h"
 #include "frontends/libretro/analog.h"
+#include "frontends/libretro/rdirectsound.h"
 
 namespace
 {
@@ -90,7 +92,7 @@ void retro_get_system_av_info(retro_system_av_info *info)
   info->geometry.aspect_ratio = 0;
 
   info->timing.fps            = 60;
-  info->timing.sample_rate    = 0;
+  info->timing.sample_rate    = SPKR_SAMPLE_RATE;
 }
 
 void retro_set_environment(retro_environment_t cb)
@@ -117,8 +119,11 @@ void retro_set_environment(retro_environment_t cb)
 
   cb(RETRO_ENVIRONMENT_SET_CONTROLLER_INFO, (void*)ports);
 
-  retro_keyboard_callback callback = {&Game::keyboardCallback};
+  retro_keyboard_callback keyboardCallback = {&Game::keyboardCallback};
-  cb(RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK, &callback);
+  cb(RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK, &keyboardCallback);
+
+  retro_audio_buffer_status_callback audioCallback = {&RDirectSound::bufferStatusCallback};
+  cb(RETRO_ENVIRONMENT_SET_AUDIO_BUFFER_STATUS_CALLBACK, &audioCallback);
 }
 
 void retro_set_audio_sample(retro_audio_sample_t cb)
@@ -156,6 +161,8 @@ void retro_run(void)
   game->processInputEvents();
   game->executeOneFrame();
   game->drawVideoBuffer();
+  const size_t ms = (1000 + 60 - 1) / 60; // round up
+  RDirectSound::writeAudio(ms);
 }
 
 bool retro_load_game(const retro_game_info *info)

source/frontends/libretro/rdirectsound.cpp

@@ -1,10 +1,181 @@
-#include <linux/interface.h>
+#include "frontends/libretro/rdirectsound.h"
+#include "frontends/libretro/environment.h"
+
+#include "linux/windows/dsound.h"
+
+#include <unordered_map>
+#include <memory>
+#include <iostream>
+#include <iomanip>
+#include <cmath>
+
+namespace
+{
+
+  class DirectSoundGenerator
+  {
+  public:
+    DirectSoundGenerator(IDirectSoundBuffer * buffer);
+
+    void writeAudio(const size_t ms);
+    void playSilence(const size_t ms);
+
+  private:
+    IDirectSoundBuffer * myBuffer;
+
+    std::vector<int16_t> myMixerBuffer;
+
+    size_t myBytesPerSecond;
+
+    bool isRunning() const;
+
+    void mixBuffer(const void * ptr, const size_t size);
+  };
+
+
+  std::unordered_map<IDirectSoundBuffer *, std::shared_ptr<DirectSoundGenerator>> activeSoundGenerators;
+
+  DirectSoundGenerator::DirectSoundGenerator(IDirectSoundBuffer * buffer)
+    : myBuffer(buffer)
+  {
+    myBytesPerSecond = myBuffer->channels * myBuffer->sampleRate * sizeof(int16_t);
+  }
+
+  bool DirectSoundGenerator::isRunning() const
+  {
+    DWORD dwStatus;
+    myBuffer->GetStatus(&dwStatus);
+    if (!(dwStatus & DSBSTATUS_PLAYING))
+    {
+      return false;
+    }
+    else
+    {
+      // for now, just play speaker audio
+      return myBuffer->channels == 1;
+    }
+  }
+
+  void DirectSoundGenerator::mixBuffer(const void * ptr, const size_t size)
+  {
+    const int16_t frames = size / (sizeof(int16_t) * myBuffer->channels);
+    const int16_t * data = static_cast<const int16_t *>(ptr);
+
+    if (myBuffer->channels == 2)
+    {
+      myMixerBuffer.assign(data, data + frames * myBuffer->channels);
+    }
+    else
+    {
+      myMixerBuffer.resize(2 * size);
+      for (int16_t i = 0; i < frames; ++i)
+      {
+	myMixerBuffer[i * 2] = data[i];
+	myMixerBuffer[i * 2 + 1] = data[i];
+      }
+    }
+
+    const double logVolume = myBuffer->GetLogarithmicVolume();
+    // same formula as QAudio::convertVolume()
+    const double linVolume = logVolume > 0.99 ? 1.0 : -std::log(1.0 - logVolume) / std::log(100.0);
+    const int16_t rvolume = int16_t(linVolume * 128);
+
+    for (int16_t & sample : myMixerBuffer)
+    {
+      sample = (sample * rvolume) / 128;
+    }
+
+    audio_batch_cb(myMixerBuffer.data(), frames);
+  }
+
+  void DirectSoundGenerator::playSilence(const size_t ms)
+  {
+    if (!isRunning())
+    {
+      return;
+    }
+
+    const size_t frames = ms * myBuffer->sampleRate / 1000;
+    const size_t bytesToWrite = frames * sizeof(int16_t) * 2;
+    myMixerBuffer.resize(bytesToWrite);
+    std::fill(myMixerBuffer.begin(), myMixerBuffer.end(), 0);
+    audio_batch_cb(myMixerBuffer.data(), frames);
+  }
+
+  void DirectSoundGenerator::writeAudio(const size_t ms)
+  {
+    // this is autostart as we only do for the palying buffers
+    // and AW might activate one later
+    if (!isRunning())
+    {
+      return;
+    }
+
+    const size_t bytesToRead = ms * myBytesPerSecond / 1000;
+
+    LPVOID lpvAudioPtr1, lpvAudioPtr2;
+    DWORD dwAudioBytes1, dwAudioBytes2;
+    myBuffer->Read(bytesToRead, &lpvAudioPtr1, &dwAudioBytes1, &lpvAudioPtr2, &dwAudioBytes2);
+
+    if (lpvAudioPtr1 && dwAudioBytes1)
+    {
+      mixBuffer(lpvAudioPtr1, dwAudioBytes1);
+    }
+    if (lpvAudioPtr2 && dwAudioBytes2)
+    {
+      mixBuffer(lpvAudioPtr2, dwAudioBytes2);
+    }
+  }
+
+}
 
-// Mockingboard
 void registerSoundBuffer(IDirectSoundBuffer * buffer)
 {
+  const std::shared_ptr<DirectSoundGenerator> generator = std::make_shared<DirectSoundGenerator>(buffer);
+  activeSoundGenerators[buffer] = generator;
 }
 
 void unregisterSoundBuffer(IDirectSoundBuffer * buffer)
 {
+  const auto it = activeSoundGenerators.find(buffer);
+  if (it != activeSoundGenerators.end())
+  {
+    activeSoundGenerators.erase(it);
+  }
+}
+
+namespace RDirectSound
+{
+
+  void writeAudio(const size_t ms)
+  {
+    for (auto & it : activeSoundGenerators)
+    {
+      const std::shared_ptr<DirectSoundGenerator> & generator = it.second;
+      generator->writeAudio(ms);
+    }
+  }
+
+  void playSilence(const size_t ms)
+  {
+    for (auto & it : activeSoundGenerators)
+    {
+      const std::shared_ptr<DirectSoundGenerator> & generator = it.second;
+      generator->playSilence(ms);
+    }
+  }
+
+  void bufferStatusCallback(bool active, unsigned occupancy, bool underrun_likely)
+  {
+    if (active)
+    {
+      // I am not sure this is any useful
+      if (underrun_likely || occupancy < 40)
+      {
+	log_cb(RETRO_LOG_INFO, "RA2: %s occupancy = %d, underrun_likely = %d\n", __FUNCTION__, occupancy, underrun_likely);
+	playSilence(10);
+      }
+    }
+  }
+
 }

source/frontends/libretro/rdirectsound.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <cstdlib>
+
+namespace RDirectSound
+{
+  void writeAudio(const size_t ms);
+  void bufferStatusCallback(bool active, unsigned occupancy, bool underrun_likely);
+}