Move shared frontend code from SDL to a seperate project

src/frontend-common/sdl_audio_stream.cpp

@@ -0,0 +1,63 @@
+#include "sdl_audio_stream.h"
+#include "common/assert.h"
+#include "common/log.h"
+#include <SDL.h>
+Log_SetChannel(SDLAudioStream);
+
+SDLAudioStream::SDLAudioStream() = default;
+
+SDLAudioStream::~SDLAudioStream()
+{
+  if (m_is_open)
+    SDLAudioStream::CloseDevice();
+}
+
+bool SDLAudioStream::OpenDevice()
+{
+  DebugAssert(!m_is_open);
+
+  SDL_AudioSpec spec = {};
+  spec.freq = m_output_sample_rate;
+  spec.channels = static_cast<Uint8>(m_channels);
+  spec.format = AUDIO_S16;
+  spec.samples = static_cast<Uint16>(m_buffer_size);
+  spec.callback = AudioCallback;
+  spec.userdata = static_cast<void*>(this);
+
+  SDL_AudioSpec obtained = {};
+  if (SDL_OpenAudio(&spec, &obtained) < 0)
+  {
+    Log_ErrorPrintf("SDL_OpenAudio failed");
+    return false;
+  }
+
+  m_is_open = true;
+  return true;
+}
+
+void SDLAudioStream::PauseDevice(bool paused)
+{
+  SDL_PauseAudio(paused ? 1 : 0);
+}
+
+void SDLAudioStream::CloseDevice()
+{
+  DebugAssert(m_is_open);
+  SDL_CloseAudio();
+  m_is_open = false;
+}
+
+void SDLAudioStream::AudioCallback(void* userdata, uint8_t* stream, int len)
+{
+  SDLAudioStream* const this_ptr = static_cast<SDLAudioStream*>(userdata);
+  const u32 num_samples = len / sizeof(SampleType) / this_ptr->m_channels;
+  const u32 read_samples = this_ptr->ReadSamples(reinterpret_cast<SampleType*>(stream), num_samples);
+  const u32 silence_samples = num_samples - read_samples;
+  if (silence_samples > 0)
+  {
+    std::memset(reinterpret_cast<SampleType*>(stream) + (read_samples * this_ptr->m_channels), 0,
+                silence_samples * this_ptr->m_channels * sizeof(SampleType));
+  }
+}
+
+void SDLAudioStream::BufferAvailable() {}