sdl2_s.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifdef WITH_SDL2
 
#include "../stdafx.h"
 
#include "../mixer.h"
#include "sdl_s.h"
#include <SDL.h>
 
#include "../safeguards.h"
 
static FSoundDriver_SDL iFSoundDriver_SDL;
 
static void CDECL fill_sound_buffer(void *, Uint8 *stream, int len)
{
  MxMixSamples(stream, len / 4);
}
 
std::optional<std::string_view> SoundDriver_SDL::Start(const StringList &parm)
{
  SDL_AudioSpec spec;
  SDL_AudioSpec spec_actual;
 
  /* Only initialise SDL if the video driver hasn't done it already */
  int ret_code = 0;
  if (SDL_WasInit(SDL_INIT_EVERYTHING) == 0) {
    ret_code = SDL_Init(SDL_INIT_AUDIO);
  } else if (SDL_WasInit(SDL_INIT_AUDIO) == 0) {
    ret_code = SDL_InitSubSystem(SDL_INIT_AUDIO);
  }
  if (ret_code == -1) return SDL_GetError();
 
  spec.freq = GetDriverParamInt(parm, "hz", 44100);
  spec.format = AUDIO_S16SYS;
  spec.channels = 2;
  spec.samples = GetDriverParamInt(parm, "samples", 1024);
  spec.callback = fill_sound_buffer;
  SDL_AudioDeviceID dev = SDL_OpenAudioDevice(nullptr, 0, &spec, &spec_actual, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE);
  MxInitialize(spec_actual.freq);
  SDL_PauseAudioDevice(dev, 0);
  return std::nullopt;
}
 
void SoundDriver_SDL::Stop()
{
  SDL_CloseAudio();
  SDL_QuitSubSystem(SDL_INIT_AUDIO);
  if (SDL_WasInit(SDL_INIT_EVERYTHING) == 0) {
    SDL_Quit(); // If there's nothing left, quit SDL
  }
}
 
#endif /* WITH_SDL2 */