1 files changed, 107 insertions, 0 deletions
diff --git a/sound/softsynth/emumidi.h b/sound/softsynth/emumidi.h
new file mode 100644
index 0000000000..34cd4b0983
--- /dev/null
+++ b/sound/softsynth/emumidi.h
@@ -0,0 +1,107 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2001-2004 The ScummVM project
+ *
+ * This program 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; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * $Header$
+ */
+
+#include "stdafx.h"
+#include "sound/audiostream.h"
+#include "sound/mididrv.h"
+#include "sound/mixer.h"
+
+#define FIXP_SHIFT 16
+
+class MidiDriver_Emulated : public AudioStream, public MidiDriver {
+protected:
+	bool _isOpen;
+	SoundMixer *_mixer;
+
+private:
+	Timer::TimerProc _timerProc;
+	void *_timerParam;
+
+	int _nextTick;
+	int _samplesPerTick;
+
+protected:
+	virtual void generateSamples(int16 *buf, int len) = 0;
+	virtual void onTimer() {}
+
+	int _baseFreq;
+
+public:
+	MidiDriver_Emulated(SoundMixer *mixer) : _mixer(mixer) {
+		_isOpen = false;
+	
+		_timerProc = 0;
+		_timerParam = 0;
+	
+		_nextTick = 0;
+		_samplesPerTick = 0;
+
+		_baseFreq = 250;
+	}
+
+	int open() {
+		_isOpen = true;
+
+		int d = getRate() / _baseFreq;
+		int r = getRate() % _baseFreq;
+
+		// This is equivalent to (getRate() << FIXP_SHIFT) / BASE_FREQ
+		// but less prone to arithmetic overflow.
+
+		_samplesPerTick = (d << FIXP_SHIFT) + (r << FIXP_SHIFT) / _baseFreq;
+		return 0;
+	}
+
+	void setTimerCallback(void *timer_param, Timer::TimerProc timer_proc) {
+		_timerProc = timer_proc;
+		_timerParam = timer_param;
+	}
+
+	uint32 getBaseTempo() { return 1000000 / _baseFreq; }
+
+
+	// AudioStream API
+	int readBuffer(int16 *data, const int numSamples) {
+		const int stereoFactor = isStereo() ? 2 : 1;
+		int len = numSamples / stereoFactor;
+		int step;
+
+		do {
+			step = len;
+			if (step > (_nextTick >> FIXP_SHIFT))
+				step = (_nextTick >> FIXP_SHIFT);
+
+			generateSamples(data, step);
+	
+			_nextTick -= step << FIXP_SHIFT;
+			if (!(_nextTick >> FIXP_SHIFT)) {
+				if (_timerProc)
+					(*_timerProc)(_timerParam);
+				onTimer();
+				_nextTick += _samplesPerTick;
+			}
+			data += step * stereoFactor;
+			len -= step;
+		} while (len);
+
+		return numSamples;
+	}
+	bool endOfData() const { return false; }
+};