(svn r14631) -Add: support for Allegro as sound backend.

src/sound/allegro_s.cpp

@@ -0,0 +1,74 @@
+/* $Id$ */
+
+/** @file allegro_s.cpp Playing sound via Allegro. */
+
+#ifdef WITH_ALLEGRO
+
+#include "../stdafx.h"
+
+#include "../driver.h"
+#include "../mixer.h"
+#include "../sdl.h"
+#include "allegro_s.h"
+#include <allegro.h>
+
+static FSoundDriver_Allegro iFSoundDriver_Allegro;
+/** The stream we are writing too */
+static AUDIOSTREAM *_stream = NULL;
+/** The number of samples in the buffer */
+static const int BUFFER_SIZE = 512;
+
+void SoundDriver_Allegro::MainLoop()
+{
+	/* We haven't opened a stream yet */
+	if (_stream == NULL) return;
+
+	void *data = get_audio_stream_buffer(_stream);
+	/* We don't have to fill the stream yet */
+	if (data == NULL) return;
+
+	/* Mix the samples */
+	MxMixSamples(data, BUFFER_SIZE);
+
+	/* Allegro sound is always unsigned, so we need to correct that */
+	uint16 *snd = (uint16*)data;
+	for (int i = 0; i < BUFFER_SIZE * 2; i++) snd[i] ^= 0x8000;
+
+	/* Tell we've filled the stream */
+	free_audio_stream_buffer(_stream);
+}
+
+/** There are multiple modules that might be using Allegro and
+ * Allegro can only be initiated once. */
+extern int _allegro_count;
+
+const char *SoundDriver_Allegro::Start(const char * const *parm)
+{
+	if (_allegro_count == 0 && install_allegro(SYSTEM_AUTODETECT, &errno, NULL)) return NULL;
+	_allegro_count++;
+
+	/* Initialise the sound */
+	if (install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, NULL) != 0) return NULL;
+
+	/* Okay, there's no soundcard */
+	if (digi_card == DIGI_NONE) {
+		DEBUG(driver, 0, "allegro: no sound card found");
+		return NULL;
+	}
+
+	_stream = play_audio_stream(BUFFER_SIZE, 16, true, 11025, 255, 128);
+	return NULL;
+}
+
+void SoundDriver_Allegro::Stop()
+{
+	if (_stream != NULL) {
+		stop_audio_stream(_stream);
+		_stream = NULL;
+	}
+	remove_sound();
+
+	if (--_allegro_count == 0) allegro_exit();
+}
+
+#endif /* WITH_ALLEGRO */