allegro_s.cpp

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00001 /* $Id: allegro_s.cpp 20286 2010-08-01 19:44:49Z frosch $ */
00002 
00003 /*
00004  * This file is part of OpenTTD.
00005  * 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.
00006  * 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.
00007  * 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/>.
00008  */
00009 
00012 #ifdef WITH_ALLEGRO
00013 
00014 #include "../stdafx.h"
00015 
00016 #include "../mixer.h"
00017 #include "../debug.h"
00018 #include "allegro_s.h"
00019 #include <allegro.h>
00020 
00021 static FSoundDriver_Allegro iFSoundDriver_Allegro;
00023 static AUDIOSTREAM *_stream = NULL;
00025 static int _buffer_size;
00026 
00027 void SoundDriver_Allegro::MainLoop()
00028 {
00029   /* We haven't opened a stream yet */
00030   if (_stream == NULL) return;
00031 
00032   void *data = get_audio_stream_buffer(_stream);
00033   /* We don't have to fill the stream yet */
00034   if (data == NULL) return;
00035 
00036   /* Mix the samples */
00037   MxMixSamples(data, _buffer_size);
00038 
00039   /* Allegro sound is always unsigned, so we need to correct that */
00040   uint16 *snd = (uint16*)data;
00041   for (int i = 0; i < _buffer_size * 2; i++) snd[i] ^= 0x8000;
00042 
00043   /* Tell we've filled the stream */
00044   free_audio_stream_buffer(_stream);
00045 }
00046 
00051 extern int _allegro_instance_count;
00052 
00053 const char *SoundDriver_Allegro::Start(const char * const *parm)
00054 {
00055   if (_allegro_instance_count == 0 && install_allegro(SYSTEM_AUTODETECT, &errno, NULL)) {
00056     DEBUG(driver, 0, "allegro: install_allegro failed '%s'", allegro_error);
00057     return "Failed to set up Allegro";
00058   }
00059   _allegro_instance_count++;
00060 
00061   /* Initialise the sound */
00062   if (install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, NULL) != 0) {
00063     DEBUG(driver, 0, "allegro: install_sound failed '%s'", allegro_error);
00064     return "Failed to set up Allegro sound";
00065   }
00066 
00067   /* Okay, there's no soundcard */
00068   if (digi_card == DIGI_NONE) {
00069     DEBUG(driver, 0, "allegro: no sound card found");
00070     return "No sound card found";
00071   }
00072 
00073   int hz = GetDriverParamInt(parm, "hz", 44100);
00074   _buffer_size = GetDriverParamInt(parm, "samples", 1024) * hz / 11025;
00075   _stream = play_audio_stream(_buffer_size, 16, true, hz, 255, 128);
00076   MxInitialize(hz);
00077   return NULL;
00078 }
00079 
00080 void SoundDriver_Allegro::Stop()
00081 {
00082   if (_stream != NULL) {
00083     stop_audio_stream(_stream);
00084     _stream = NULL;
00085   }
00086   remove_sound();
00087 
00088   if (--_allegro_instance_count == 0) allegro_exit();
00089 }
00090 
00091 #endif /* WITH_ALLEGRO */

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