Split off the actual mixing part of SoundBlaster

svn-id: r31938

1 files changed, 205 insertions, 0 deletions

diff --git a/engines/gob/sound/soundmixer.cpp b/engines/gob/sound/soundmixer.cpp
new file mode 100644
index 0000000000..f85073ad61
--- /dev/null
+++ b/engines/gob/sound/soundmixer.cpp
@@ -0,0 +1,205 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#include "gob/sound/soundmixer.h"
+
+namespace Gob {
+
+SoundMixer::SoundMixer(Audio::Mixer &mixer) : _mixer(&mixer) {
+	_playingSound = 0;
+
+	_rate = _mixer->getOutputRate();
+	_end = true;
+	_data = 0;
+	_length = 0;
+	_freq = 0;
+	_repCount = 0;
+
+	_offset = 0;
+	_offsetFrac = 0;
+	_offsetInc = 0;
+
+	_cur = 0;
+	_last = 0;
+
+	_fade = false;
+	_fadeVol = 65536;
+	_fadeVolStep = 0;
+	_fadeSamples = 0;
+	_curFadeSamples = 0;
+
+	_mixer->playInputStream(Audio::Mixer::kSFXSoundType, &_handle,
+			this, -1, 255, 0, false, true);
+}
+
+SoundMixer::~SoundMixer() {
+	_mixer->stopHandle(_handle);
+}
+
+bool SoundMixer::isPlaying() const {
+	return !_end;
+}
+
+char SoundMixer::getPlayingSound() const {
+	return _playingSound;
+}
+
+void SoundMixer::stop(int16 fadeLength) {
+	Common::StackLock slock(_mutex);
+
+	if (fadeLength <= 0) {
+		_data = 0;
+		_end = true;
+		_playingSound = 0;
+		return;
+	}
+
+	_fade = true;
+	_fadeVol = 65536;
+	_fadeSamples = (int) (fadeLength * (((double) _rate) / 10.0));
+	_fadeVolStep = MAX((int32) 1, (int32) (65536 / _fadeSamples));
+	_curFadeSamples = 0;
+}
+
+void SoundMixer::setRepeating(int32 repCount) {
+	Common::StackLock slock(_mutex);
+
+	_repCount = repCount;
+}
+
+void SoundMixer::setSample(SoundDesc &sndDesc, int16 repCount, int16 frequency,
+		int16 fadeLength) {
+
+	if (frequency <= 0)
+		frequency = sndDesc._frequency;
+
+	sndDesc._repCount = repCount - 1;
+	sndDesc._frequency = frequency;
+
+	_data = (int8 *) sndDesc.getData();
+	_length = sndDesc.size();
+	_freq = frequency;
+
+	_repCount = repCount;
+	_end = false;
+	_playingSound = 1;
+
+	_offset = 0;
+	_offsetFrac = 0;
+	_offsetInc = (_freq << FRAC_BITS) / _rate;
+
+	_last = _cur;
+	_cur = _data[0];
+
+	_curFadeSamples = 0;
+	if (fadeLength == 0) {
+		_fade = false;
+		_fadeVol = 65536;
+		_fadeSamples = 0;
+		_fadeVolStep = 0;
+	} else {
+		_fade = true;
+		_fadeVol = 0;
+		_fadeSamples = (int) (fadeLength * (((double) _rate) / 10.0));
+		_fadeVolStep = - MAX((int32) 1, (int32) (65536 / _fadeSamples));
+	}
+}
+
+void SoundMixer::play(SoundDesc &sndDesc, int16 repCount, int16 frequency,
+		int16 fadeLength) {
+	Common::StackLock slock(_mutex);
+
+	if (!_end)
+		return;
+
+	setSample(sndDesc, repCount, frequency, fadeLength);
+}
+
+void SoundMixer::checkEndSample() {
+	if ((_repCount == -1) || (--_repCount > 0)) {
+		_offset = 0;
+		_offsetFrac = 0;
+		_end = false;
+		_playingSound = 1;
+	} else {
+		_end = true;
+		_playingSound = 0;
+	}
+}
+
+int SoundMixer::readBuffer(int16 *buffer, const int numSamples) {
+	Common::StackLock slock(_mutex);
+
+	for (int i = 0; i < numSamples; i++) {
+		if (!_data)
+			return i;
+		if (_end || (_offset >= _length))
+			checkEndSample();
+		if (_end)
+			return i;
+
+		// Linear interpolation. See sound/rate.cpp
+
+		int16 val = (_last + (((_cur - _last) * _offsetFrac +
+					FRAC_HALF) >> FRAC_BITS)) << 8;
+		*buffer++ = (val * _fadeVol) >> 16;
+
+		_offsetFrac += _offsetInc;
+
+		// Was there an integral change?
+		if (fracToInt(_offsetFrac) > 0) {
+			_last = _cur;
+			_cur = _data[_offset];
+			_offset += fracToInt(_offsetFrac);
+			_offsetFrac &= FRAC_LO_MASK;
+		}
+
+		if (_fade) {
+
+			if (++_curFadeSamples >= _fadeSamples)
+				endFade();
+			else
+				_fadeVol -= _fadeVolStep;
+
+			if (_fadeVol < 0)
+				_fadeVol = 0;
+
+		}
+	}
+	return numSamples;
+}
+
+void SoundMixer::endFade() {
+	if (_fadeVolStep > 0) {
+		_data = 0;
+		_end = true;
+		_playingSound = 0;
+	} else {
+		_fadeVol = 65536;
+		_fade = false;
+	}
+}
+
+} // End of namespace Gob