src/sound/allegro_s.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * 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.
   4  * 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.
   5  * 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/>.
   6  */
   7
   8 /** @file allegro_s.cpp Playing sound via Allegro. */
   9
  10 #ifdef WITH_ALLEGRO
  11
  12 #include "../stdafx.h"
  13
  14 #include "../mixer.h"
  15 #include "../debug.h"
  16 #include "allegro_s.h"
  17 #include <allegro.h>
  18
  19 #include "../safeguards.h"
  20
  21 static FSoundDriver_Allegro iFSoundDriver_Allegro;
  22 /** The stream we are writing too */
  23 static AUDIOSTREAM *_stream = nullptr;
  24 /** The number of samples in the buffer */
  25 static int _buffer_size;
  26
  27 void SoundDriver_Allegro::MainLoop()
  28 {
  29         /* We haven't opened a stream yet */
  30         if (_stream == nullptr) return;
  31
  32         void *data = get_audio_stream_buffer(_stream);
  33         /* We don't have to fill the stream yet */
  34         if (data == nullptr) return;
  35
  36         /* Mix the samples */
  37         MxMixSamples(data, _buffer_size);
  38
  39         /* Allegro sound is always unsigned, so we need to correct that */
  40         uint16_t *snd = (uint16_t*)data;
  41         for (int i = 0; i < _buffer_size * 2; i++) snd[i] ^= 0x8000;
  42
  43         /* Tell we've filled the stream */
  44         free_audio_stream_buffer(_stream);
  45 }
  46
  47 /**
  48  * There are multiple modules that might be using Allegro and
  49  * Allegro can only be initiated once.
  50  */
  51 extern int _allegro_instance_count;
  52
  53 std::optional<std::string_view> SoundDriver_Allegro::Start(const StringList &parm)
  54 {
  55         if (_allegro_instance_count == 0 && install_allegro(SYSTEM_AUTODETECT, &errno, nullptr)) {
  56                 Debug(driver, 0, "allegro: install_allegro failed '{}'", allegro_error);
  57                 return "Failed to set up Allegro";
  58         }
  59         _allegro_instance_count++;
  60
  61         /* Initialise the sound */
  62         if (install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, nullptr) != 0) {
  63                 Debug(driver, 0, "allegro: install_sound failed '{}'", allegro_error);
  64                 return "Failed to set up Allegro sound";
  65         }
  66
  67         /* Okay, there's no soundcard */
  68         if (digi_card == DIGI_NONE) {
  69                 Debug(driver, 0, "allegro: no sound card found");
  70                 return "No sound card found";
  71         }
  72
  73         int hz = GetDriverParamInt(parm, "hz", 44100);
  74         _buffer_size = GetDriverParamInt(parm, "samples", 1024) * hz / 11025;
  75         _stream = play_audio_stream(_buffer_size, 16, true, hz, 255, 128);
  76         MxInitialize(hz);
  77         return std::nullopt;
  78 }
  79
  80 void SoundDriver_Allegro::Stop()
  81 {
  82         if (_stream != nullptr) {
  83                 stop_audio_stream(_stream);
  84                 _stream = nullptr;
  85         }
  86         remove_sound();
  87
  88         if (--_allegro_instance_count == 0) allegro_exit();
  89 }
  90
  91 #endif /* WITH_ALLEGRO */