MT32: Update the MT32 emulator to a newer munt commit

Previous munt commit was f969d20 (Nov 15, 2012)
Current munt commit is 84b2819 (Dec 22, 2012)

We are still missing the changes from commit 788f7b1 onwards (Dec 22,
2012). There are bigger ROM access-related changes from that point,
which we'll have to integrate as well.

1 files changed, 395 insertions, 0 deletions

diff --git a/audio/softsynth/mt32/BReverbModel.cpp b/audio/softsynth/mt32/BReverbModel.cpp
new file mode 100644
index 0000000000..b5f4467c20
--- /dev/null
+++ b/audio/softsynth/mt32/BReverbModel.cpp
@@ -0,0 +1,395 @@
+/* Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009 Dean Beeler, Jerome Fisher
+ * Copyright (C) 2011, 2012 Dean Beeler, Jerome Fisher, Sergey V. Mikayev
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published by
+ *  the Free Software Foundation, either version 2.1 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 Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "mt32emu.h"
+
+#if MT32EMU_USE_REVERBMODEL == 2
+
+#include "BReverbModel.h"
+
+// Analysing of state of reverb RAM address lines gives exact sizes of the buffers of filters used. This also indicates that
+// the reverb model implemented in the real devices consists of three series allpass filters preceded by a non-feedback comb (or a delay with a LPF)
+// and followed by three parallel comb filters
+
+namespace MT32Emu {
+
+// Because LA-32 chip makes it's output available to process by the Boss chip with a significant delay,
+// the Boss chip puts to the buffer the LA32 dry output when it is ready and performs processing of the _previously_ latched data.
+// Of course, the right way would be to use a dedicated variable for this, but our reverb model is way higher level,
+// so we can simply increase the input buffer size.
+static const Bit32u PROCESS_DELAY = 1;
+
+static const Bit32u MODE_3_ADDITIONAL_DELAY = 1;
+static const Bit32u MODE_3_FEEDBACK_DELAY = 1;
+
+// Default reverb settings for modes 0-2. These correspond to CM-32L / LAPC-I "new" reverb settings. MT-32 reverb is a bit different.
+// Found by tracing reverb RAM data lines (thanks go to Lord_Nightmare & balrog).
+
+static const Bit32u MODE_0_NUMBER_OF_ALLPASSES = 3;
+static const Bit32u MODE_0_ALLPASSES[] = {994, 729, 78};
+static const Bit32u MODE_0_NUMBER_OF_COMBS = 4; // Well, actually there are 3 comb filters, but the entrance LPF + delay can be processed via a hacked comb.
+static const Bit32u MODE_0_COMBS[] = {705 + PROCESS_DELAY, 2349, 2839, 3632};
+static const Bit32u MODE_0_OUTL[] = {2349, 141, 1960};
+static const Bit32u MODE_0_OUTR[] = {1174, 1570, 145};
+static const Bit32u MODE_0_COMB_FACTOR[] = {0xA0, 0x60, 0x60, 0x60};
+static const Bit32u MODE_0_COMB_FEEDBACK[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                                              0x28, 0x48, 0x60, 0x78, 0x80, 0x88, 0x90, 0x98,
+                                              0x28, 0x48, 0x60, 0x78, 0x80, 0x88, 0x90, 0x98,
+                                              0x28, 0x48, 0x60, 0x78, 0x80, 0x88, 0x90, 0x98};
+static const Bit32u MODE_0_DRY_AMP[] = {0xA0, 0xA0, 0xA0, 0xA0, 0xB0, 0xB0, 0xB0, 0xD0};
+static const Bit32u MODE_0_WET_AMP[] = {0x10, 0x30, 0x50, 0x70, 0x90, 0xC0, 0xF0, 0xF0};
+static const Bit32u MODE_0_LPF_AMP = 0x60;
+
+static const Bit32u MODE_1_NUMBER_OF_ALLPASSES = 3;
+static const Bit32u MODE_1_ALLPASSES[] = {1324, 809, 176};
+static const Bit32u MODE_1_NUMBER_OF_COMBS = 4; // Same as for mode 0 above
+static const Bit32u MODE_1_COMBS[] = {961 + PROCESS_DELAY, 2619, 3545, 4519};
+static const Bit32u MODE_1_OUTL[] = {2618, 1760, 4518};
+static const Bit32u MODE_1_OUTR[] = {1300, 3532, 2274};
+static const Bit32u MODE_1_COMB_FACTOR[] = {0x80, 0x60, 0x60, 0x60};
+static const Bit32u MODE_1_COMB_FEEDBACK[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+											  0x28, 0x48, 0x60, 0x70, 0x78, 0x80, 0x90, 0x98,
+											  0x28, 0x48, 0x60, 0x78, 0x80, 0x88, 0x90, 0x98,
+											  0x28, 0x48, 0x60, 0x78, 0x80, 0x88, 0x90, 0x98};
+static const Bit32u MODE_1_DRY_AMP[] = {0xA0, 0xA0, 0xB0, 0xB0, 0xB0, 0xB0, 0xB0, 0xE0};
+static const Bit32u MODE_1_WET_AMP[] = {0x10, 0x30, 0x50, 0x70, 0x90, 0xC0, 0xF0, 0xF0};
+static const Bit32u MODE_1_LPF_AMP = 0x60;
+
+static const Bit32u MODE_2_NUMBER_OF_ALLPASSES = 3;
+static const Bit32u MODE_2_ALLPASSES[] = {969, 644, 157};
+static const Bit32u MODE_2_NUMBER_OF_COMBS = 4; // Same as for mode 0 above
+static const Bit32u MODE_2_COMBS[] = {116 + PROCESS_DELAY, 2259, 2839, 3539};
+static const Bit32u MODE_2_OUTL[] = {2259, 718, 1769};
+static const Bit32u MODE_2_OUTR[] = {1136, 2128, 1};
+static const Bit32u MODE_2_COMB_FACTOR[] = {0, 0x20, 0x20, 0x20};
+static const Bit32u MODE_2_COMB_FEEDBACK[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                                              0x30, 0x58, 0x78, 0x88, 0xA0, 0xB8, 0xC0, 0xD0,
+                                              0x30, 0x58, 0x78, 0x88, 0xA0, 0xB8, 0xC0, 0xD0,
+                                              0x30, 0x58, 0x78, 0x88, 0xA0, 0xB8, 0xC0, 0xD0};
+static const Bit32u MODE_2_DRY_AMP[] = {0xA0, 0xA0, 0xB0, 0xB0, 0xB0, 0xB0, 0xC0, 0xE0};
+static const Bit32u MODE_2_WET_AMP[] = {0x10, 0x30, 0x50, 0x70, 0x90, 0xC0, 0xF0, 0xF0};
+static const Bit32u MODE_2_LPF_AMP = 0x80;
+
+static const Bit32u MODE_3_NUMBER_OF_ALLPASSES = 0;
+static const Bit32u MODE_3_NUMBER_OF_COMBS = 1;
+static const Bit32u MODE_3_DELAY[] = {16000 + MODE_3_FEEDBACK_DELAY + PROCESS_DELAY + MODE_3_ADDITIONAL_DELAY};
+static const Bit32u MODE_3_OUTL[] = {400, 624, 960, 1488, 2256, 3472, 5280, 8000};
+static const Bit32u MODE_3_OUTR[] = {800, 1248, 1920, 2976, 4512, 6944, 10560, 16000};
+static const Bit32u MODE_3_COMB_FACTOR[] = {0x68};
+static const Bit32u MODE_3_COMB_FEEDBACK[] = {0x68, 0x60};
+static const Bit32u MODE_3_DRY_AMP[] = {0x20, 0x50, 0x50, 0x50, 0x50, 0x50, 0x50, 0x50};
+static const Bit32u MODE_3_WET_AMP[] = {0x18, 0x18, 0x28, 0x40, 0x60, 0x80, 0xA8, 0xF8};
+
+static const BReverbSettings REVERB_MODE_0_SETTINGS = {MODE_0_NUMBER_OF_ALLPASSES, MODE_0_ALLPASSES, MODE_0_NUMBER_OF_COMBS, MODE_0_COMBS, MODE_0_OUTL, MODE_0_OUTR, MODE_0_COMB_FACTOR, MODE_0_COMB_FEEDBACK, MODE_0_DRY_AMP, MODE_0_WET_AMP, MODE_0_LPF_AMP};
+static const BReverbSettings REVERB_MODE_1_SETTINGS = {MODE_1_NUMBER_OF_ALLPASSES, MODE_1_ALLPASSES, MODE_1_NUMBER_OF_COMBS, MODE_1_COMBS, MODE_1_OUTL, MODE_1_OUTR, MODE_1_COMB_FACTOR, MODE_1_COMB_FEEDBACK, MODE_1_DRY_AMP, MODE_1_WET_AMP, MODE_1_LPF_AMP};
+static const BReverbSettings REVERB_MODE_2_SETTINGS = {MODE_2_NUMBER_OF_ALLPASSES, MODE_2_ALLPASSES, MODE_2_NUMBER_OF_COMBS, MODE_2_COMBS, MODE_2_OUTL, MODE_2_OUTR, MODE_2_COMB_FACTOR, MODE_2_COMB_FEEDBACK, MODE_2_DRY_AMP, MODE_2_WET_AMP, MODE_2_LPF_AMP};
+static const BReverbSettings REVERB_MODE_3_SETTINGS = {MODE_3_NUMBER_OF_ALLPASSES, NULL, MODE_3_NUMBER_OF_COMBS, MODE_3_DELAY, MODE_3_OUTL, MODE_3_OUTR, MODE_3_COMB_FACTOR, MODE_3_COMB_FEEDBACK, MODE_3_DRY_AMP, MODE_3_WET_AMP, 0};
+
+static const BReverbSettings * const REVERB_SETTINGS[] = {&REVERB_MODE_0_SETTINGS, &REVERB_MODE_1_SETTINGS, &REVERB_MODE_2_SETTINGS, &REVERB_MODE_3_SETTINGS};
+
+// This algorithm tries to emulate exactly Boss multiplication operation (at least this is what we see on reverb RAM data lines).
+// Also LA32 is suspected to use the similar one to perform PCM interpolation and ring modulation.
+static Bit32s weirdMul(Bit32s a, Bit8u addMask, Bit8u carryMask) {
+	Bit8u mask = 0x80;
+	Bit32s res = 0;
+	for (int i = 0; i < 8; i++) {
+		Bit32s carry = (a < 0) && (mask & carryMask) > 0 ? a & 1 : 0;
+		a >>= 1;
+		res += (mask & addMask) > 0 ? a + carry : 0;
+		mask >>= 1;
+	}
+	return res;
+}
+
+RingBuffer::RingBuffer(Bit32u newsize) : size(newsize), index(0) {
+	buffer = new Bit16s[size];
+}
+
+RingBuffer::~RingBuffer() {
+	delete[] buffer;
+	buffer = NULL;
+}
+
+Bit32s RingBuffer::next() {
+	if (++index >= size) {
+		index = 0;
+	}
+	return buffer[index];
+}
+
+bool RingBuffer::isEmpty() const {
+	if (buffer == NULL) return true;
+
+	Bit16s *buf = buffer;
+	for (Bit32u i = 0; i < size; i++) {
+		if (*buf < -8 || *buf > 8) return false;
+		buf++;
+	}
+	return true;
+}
+
+void RingBuffer::mute() {
+	Bit16s *buf = buffer;
+	for (Bit32u i = 0; i < size; i++) {
+		*buf++ = 0;
+	}
+}
+
+AllpassFilter::AllpassFilter(const Bit32u useSize) : RingBuffer(useSize) {}
+
+Bit32s AllpassFilter::process(const Bit32s in) {
+	// This model corresponds to the allpass filter implementation of the real CM-32L device
+	// found from sample analysis
+
+	Bit16s bufferOut = next();
+
+	// store input - feedback / 2
+	buffer[index] = in - (bufferOut >> 1);
+
+	// return buffer output + feedforward / 2
+	return bufferOut + (buffer[index] >> 1);
+}
+
+CombFilter::CombFilter(const Bit32u useSize, const Bit32u useFilterFactor) : RingBuffer(useSize), filterFactor(useFilterFactor) {}
+
+void CombFilter::process(const Bit32s in) {
+	// This model corresponds to the comb filter implementation of the real CM-32L device
+
+	// the previously stored value
+	Bit32s last = buffer[index];
+
+	// prepare input + feedback
+	Bit32s filterIn = in + weirdMul(next(), feedbackFactor, 0xF0 /* Maybe 0x80 ? */);
+
+	// store input + feedback processed by a low-pass filter
+	buffer[index] = weirdMul(last, filterFactor, 0x40) - filterIn;
+}
+
+Bit32s CombFilter::getOutputAt(const Bit32u outIndex) const {
+	return buffer[(size + index - outIndex) % size];
+}
+
+void CombFilter::setFeedbackFactor(const Bit32u useFeedbackFactor) {
+	feedbackFactor = useFeedbackFactor;
+}
+
+DelayWithLowPassFilter::DelayWithLowPassFilter(const Bit32u useSize, const Bit32u useFilterFactor, const Bit32u useAmp)
+	: CombFilter(useSize, useFilterFactor), amp(useAmp) {}
+
+void DelayWithLowPassFilter::process(const Bit32s in) {
+	// the previously stored value
+	Bit32s last = buffer[index];
+
+	// move to the next index
+	next();
+
+	// low-pass filter process
+	Bit32s lpfOut = weirdMul(last, filterFactor, 0xFF) + in;
+
+	// store lpfOut multiplied by LPF amp factor
+	buffer[index] = weirdMul(lpfOut, amp, 0xFF);
+}
+
+TapDelayCombFilter::TapDelayCombFilter(const Bit32u useSize, const Bit32u useFilterFactor) : CombFilter(useSize, useFilterFactor) {}
+
+void TapDelayCombFilter::process(const Bit32s in) {
+	// the previously stored value
+	Bit32s last = buffer[index];
+
+	// move to the next index
+	next();
+
+	// prepare input + feedback
+	// Actually, the size of the filter varies with the TIME parameter, the feedback sample is taken from the position just below the right output
+	Bit32s filterIn = in + weirdMul(getOutputAt(outR + MODE_3_FEEDBACK_DELAY), feedbackFactor, 0xF0);
+
+	// store input + feedback processed by a low-pass filter
+	buffer[index] = weirdMul(last, filterFactor, 0xF0) - filterIn;
+}
+
+Bit32s TapDelayCombFilter::getLeftOutput() const {
+	return getOutputAt(outL + PROCESS_DELAY + MODE_3_ADDITIONAL_DELAY);
+}
+
+Bit32s TapDelayCombFilter::getRightOutput() const {
+	return getOutputAt(outR + PROCESS_DELAY + MODE_3_ADDITIONAL_DELAY);
+}
+
+void TapDelayCombFilter::setOutputPositions(const Bit32u useOutL, const Bit32u useOutR) {
+	outL = useOutL;
+	outR = useOutR;
+}
+
+BReverbModel::BReverbModel(const ReverbMode mode)
+	: allpasses(NULL), combs(NULL), currentSettings(*REVERB_SETTINGS[mode]), tapDelayMode(mode == REVERB_MODE_TAP_DELAY) {}
+
+BReverbModel::~BReverbModel() {
+	close();
+}
+
+void BReverbModel::open(unsigned int /*sampleRate*/) {
+	// FIXME: filter sizes must be multiplied by sample rate to 32000Hz ratio
+	// IIR filter values depend on sample rate as well
+	if (currentSettings.numberOfAllpasses > 0) {
+		allpasses = new AllpassFilter*[currentSettings.numberOfAllpasses];
+		for (Bit32u i = 0; i < currentSettings.numberOfAllpasses; i++) {
+			allpasses[i] = new AllpassFilter(currentSettings.allpassSizes[i]);
+		}
+	}
+	combs = new CombFilter*[currentSettings.numberOfCombs];
+	if (tapDelayMode) {
+		*combs = new TapDelayCombFilter(*currentSettings.combSizes, *currentSettings.filterFactors);
+	} else {
+		combs[0] = new DelayWithLowPassFilter(currentSettings.combSizes[0], currentSettings.filterFactors[0], currentSettings.lpfAmp);
+		for (Bit32u i = 1; i < currentSettings.numberOfCombs; i++) {
+			combs[i] = new CombFilter(currentSettings.combSizes[i], currentSettings.filterFactors[i]);
+		}
+	}
+	mute();
+}
+
+void BReverbModel::close() {
+	if (allpasses != NULL) {
+		for (Bit32u i = 0; i < currentSettings.numberOfAllpasses; i++) {
+			if (allpasses[i] != NULL) {
+				delete allpasses[i];
+				allpasses[i] = NULL;
+			}
+		}
+		delete[] allpasses;
+		allpasses = NULL;
+	}
+	if (combs != NULL) {
+		for (Bit32u i = 0; i < currentSettings.numberOfCombs; i++) {
+			if (combs[i] != NULL) {
+				delete combs[i];
+				combs[i] = NULL;
+			}
+		}
+		delete[] combs;
+		combs = NULL;
+	}
+}
+
+void BReverbModel::mute() {
+	if (allpasses != NULL) {
+		for (Bit32u i = 0; i < currentSettings.numberOfAllpasses; i++) {
+			allpasses[i]->mute();
+		}
+	}
+	if (combs != NULL) {
+		for (Bit32u i = 0; i < currentSettings.numberOfCombs; i++) {
+			combs[i]->mute();
+		}
+	}
+}
+
+void BReverbModel::setParameters(Bit8u time, Bit8u level) {
+	if (combs == NULL) return;
+	level &= 7;
+	time &= 7;
+	if (tapDelayMode) {
+		TapDelayCombFilter *comb = static_cast<TapDelayCombFilter *> (*combs);
+		comb->setOutputPositions(currentSettings.outLPositions[time], currentSettings.outRPositions[time & 7]);
+		comb->setFeedbackFactor(currentSettings.feedbackFactors[((level < 3) || (time < 6)) ? 0 : 1]);
+	} else {
+		for (Bit32u i = 0; i < currentSettings.numberOfCombs; i++) {
+			combs[i]->setFeedbackFactor(currentSettings.feedbackFactors[(i << 3) + time]);
+		}
+	}
+	if (time == 0 && level == 0) {
+		dryAmp = wetLevel = 0;
+	} else {
+		dryAmp = currentSettings.dryAmps[level];
+		wetLevel = currentSettings.wetLevels[level];
+	}
+}
+
+bool BReverbModel::isActive() const {
+	for (Bit32u i = 0; i < currentSettings.numberOfAllpasses; i++) {
+		if (!allpasses[i]->isEmpty()) return true;
+	}
+	for (Bit32u i = 0; i < currentSettings.numberOfCombs; i++) {
+		if (!combs[i]->isEmpty()) return true;
+	}
+	return false;
+}
+
+void BReverbModel::process(const float *inLeft, const float *inRight, float *outLeft, float *outRight, unsigned long numSamples) {
+	Bit32s dry, link, outL1, outR1;
+
+	for (unsigned long i = 0; i < numSamples; i++) {
+		if (tapDelayMode) {
+			dry = Bit32s(*inLeft * 8192.0f) + Bit32s(*inRight * 8192.0f);
+		} else {
+			dry = Bit32s(*inLeft * 8192.0f) / 2 + Bit32s(*inRight * 8192.0f) / 2;
+		}
+
+		// Looks like dryAmp doesn't change in MT-32 but it does in CM-32L / LAPC-I
+		dry = weirdMul(dry, dryAmp, 0xFF);
+
+		if (tapDelayMode) {
+			TapDelayCombFilter *comb = static_cast<TapDelayCombFilter *> (*combs);
+			comb->process(dry);
+			*outLeft = weirdMul(comb->getLeftOutput(), wetLevel, 0xFF) / 8192.0f;
+			*outRight = weirdMul(comb->getRightOutput(), wetLevel, 0xFF) / 8192.0f;
+		} else {
+			// Get the last stored sample before processing in order not to loose it
+			link = combs[0]->getOutputAt(currentSettings.combSizes[0] - 1);
+
+			// Entrance LPF. Note, comb.process() differs a bit here.
+			combs[0]->process(dry);
+
+			// This introduces reverb noise which actually makes output from the real Boss chip nondeterministic
+			link = link - 1;
+			link = allpasses[0]->process(link);
+			link = allpasses[1]->process(link);
+			link = allpasses[2]->process(link);
+
+			// If the output position is equal to the comb size, get it now in order not to loose it
+			outL1 = combs[1]->getOutputAt(currentSettings.outLPositions[0] - 1);
+			outL1 += outL1 >> 1;
+
+			combs[1]->process(link);
+			combs[2]->process(link);
+			combs[3]->process(link);
+
+			link = combs[2]->getOutputAt(currentSettings.outLPositions[1]);
+			link += link >> 1;
+			link += outL1;
+			link += combs[3]->getOutputAt(currentSettings.outLPositions[2]);
+			*outLeft = weirdMul(link, wetLevel, 0xFF) / 8192.0f;
+
+			outR1 = combs[1]->getOutputAt(currentSettings.outRPositions[0]);
+			outR1 += outR1 >> 1;
+			link = combs[2]->getOutputAt(currentSettings.outRPositions[1]);
+			link += link >> 1;
+			link += outR1;
+			link += combs[3]->getOutputAt(currentSettings.outRPositions[2]);
+			*outRight = weirdMul(link, wetLevel, 0xFF) / 8192.0f;
+		}
+
+		inLeft++;
+		inRight++;
+		outLeft++;
+		outRight++;
+	}
+}
+
+}
+
+#endif