src/sound/allegro_s.cpp

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /** @file allegro_s.cpp Playing sound via Allegro. */
  11
  12 #ifdef WITH_ALLEGRO
  13
  14 #include "../stdafx.h"
  15
  16 #include "../mixer.h"
  17 #include "../debug.h"
  18 #include "allegro_s.h"
  19 #include <allegro.h>
  20
  21 #include "../safeguards.h"
  22
  23 static FSoundDriver_Allegro iFSoundDriver_Allegro;
  24 /** The stream we are writing too */
  25 static AUDIOSTREAM *_stream = nullptr;
  26 /** The number of samples in the buffer */
  27 static int _buffer_size;
  28
  29 void SoundDriver_Allegro::MainLoop()
  30 {
  31         /* We haven't opened a stream yet */
  32         if (_stream == nullptr) return;
  33
  34         void *data = get_audio_stream_buffer(_stream);
  35         /* We don't have to fill the stream yet */
  36         if (data == nullptr) return;
  37
  38         /* Mix the samples */
  39         MxMixSamples(data, _buffer_size);
  40
  41         /* Allegro sound is always unsigned, so we need to correct that */
  42         uint16 *snd = (uint16*)data;
  43         for (int i = 0; i < _buffer_size * 2; i++) snd[i] ^= 0x8000;
  44
  45         /* Tell we've filled the stream */
  46         free_audio_stream_buffer(_stream);
  47 }
  48
  49 /**
  50  * There are multiple modules that might be using Allegro and
  51  * Allegro can only be initiated once.
  52  */
  53 extern int _allegro_instance_count;
  54
  55 const char *SoundDriver_Allegro::Start(const char * const *parm)
  56 {
  57         if (_allegro_instance_count == 0 && install_allegro(SYSTEM_AUTODETECT, &errno, nullptr)) {
  58                 DEBUG(driver, 0, "allegro: install_allegro failed '%s'", allegro_error);
  59                 return "Failed to set up Allegro";
  60         }
  61         _allegro_instance_count++;
  62
  63         /* Initialise the sound */
  64         if (install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, nullptr) != 0) {
  65                 DEBUG(driver, 0, "allegro: install_sound failed '%s'", allegro_error);
  66                 return "Failed to set up Allegro sound";
  67         }
  68
  69         /* Okay, there's no soundcard */
  70         if (digi_card == DIGI_NONE) {
  71                 DEBUG(driver, 0, "allegro: no sound card found");
  72                 return "No sound card found";
  73         }
  74
  75         int hz = GetDriverParamInt(parm, "hz", 44100);
  76         _buffer_size = GetDriverParamInt(parm, "samples", 1024) * hz / 11025;
  77         _stream = play_audio_stream(_buffer_size, 16, true, hz, 255, 128);
  78         MxInitialize(hz);
  79         return nullptr;
  80 }
  81
  82 void SoundDriver_Allegro::Stop()
  83 {
  84         if (_stream != nullptr) {
  85                 stop_audio_stream(_stream);
  86                 _stream = nullptr;
  87         }
  88         remove_sound();
  89
  90         if (--_allegro_instance_count == 0) allegro_exit();
  91 }
  92
  93 #endif /* WITH_ALLEGRO */