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scummvm/audio/softsynth/mt32/BReverbModel.cpp
Hubert Maier 5b98653ec3
AUDIO: Correct spelling mistake 
loose -> lose
2022-10-27 15:56:03 +02:00

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/* Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009 Dean Beeler, Jerome Fisher
* Copyright (C) 2011-2022 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 <cstddef>
#include "internals.h"
#include "BReverbModel.h"
#include "Synth.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;
// Avoid denormals degrading performance, using biased input
static const FloatSample BIAS = 1e-20f;
struct BReverbSettings {
const Bit32u numberOfAllpasses;
const Bit32u * const allpassSizes;
const Bit32u numberOfCombs;
const Bit32u * const combSizes;
const Bit32u * const outLPositions;
const Bit32u * const outRPositions;
const Bit8u * const filterFactors;
const Bit8u * const feedbackFactors;
const Bit8u * const dryAmps;
const Bit8u * const wetLevels;
const Bit8u lpfAmp;
};
// Default reverb settings for "new" reverb model implemented in CM-32L / LAPC-I.
// Found by tracing reverb RAM data lines (thanks go to Lord_Nightmare & balrog).
static const BReverbSettings &getCM32L_LAPCSettings(const ReverbMode mode) {
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 Bit8u MODE_0_COMB_FACTOR[] = {0xA0, 0x60, 0x60, 0x60};
static const Bit8u 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 Bit8u MODE_0_DRY_AMP[] = {0xA0, 0xA0, 0xA0, 0xA0, 0xB0, 0xB0, 0xB0, 0xD0};
static const Bit8u MODE_0_WET_AMP[] = {0x10, 0x30, 0x50, 0x70, 0x90, 0xC0, 0xF0, 0xF0};
static const Bit8u 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 Bit8u MODE_1_COMB_FACTOR[] = {0x80, 0x60, 0x60, 0x60};
static const Bit8u 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 Bit8u MODE_1_DRY_AMP[] = {0xA0, 0xA0, 0xB0, 0xB0, 0xB0, 0xB0, 0xB0, 0xE0};
static const Bit8u MODE_1_WET_AMP[] = {0x10, 0x30, 0x50, 0x70, 0x90, 0xC0, 0xF0, 0xF0};
static const Bit8u 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 Bit8u MODE_2_COMB_FACTOR[] = {0, 0x20, 0x20, 0x20};
static const Bit8u 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 Bit8u MODE_2_DRY_AMP[] = {0xA0, 0xA0, 0xB0, 0xB0, 0xB0, 0xB0, 0xC0, 0xE0};
static const Bit8u MODE_2_WET_AMP[] = {0x10, 0x30, 0x50, 0x70, 0x90, 0xC0, 0xF0, 0xF0};
static const Bit8u 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 Bit8u MODE_3_COMB_FACTOR[] = {0x68};
static const Bit8u MODE_3_COMB_FEEDBACK[] = {0x68, 0x60};
static const Bit8u MODE_3_DRY_AMP[] = {0x20, 0x50, 0x50, 0x50, 0x50, 0x50, 0x50, 0x50,
0x20, 0x50, 0x50, 0x50, 0x50, 0x50, 0x50, 0x50};
static const Bit8u 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};
return *REVERB_SETTINGS[mode];
}
// Default reverb settings for "old" reverb model implemented in MT-32.
// Found by tracing reverb RAM data lines (thanks go to Lord_Nightmare & balrog).
static const BReverbSettings &getMT32Settings(const ReverbMode mode) {
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; // Same as above in the new model implementation
static const Bit32u MODE_0_COMBS[] = {575 + PROCESS_DELAY, 2040, 2752, 3629};
static const Bit32u MODE_0_OUTL[] = {2040, 687, 1814};
static const Bit32u MODE_0_OUTR[] = {1019, 2072, 1};
static const Bit8u MODE_0_COMB_FACTOR[] = {0xB0, 0x60, 0x60, 0x60};
static const Bit8u MODE_0_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 Bit8u MODE_0_DRY_AMP[] = {0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80};
static const Bit8u MODE_0_WET_AMP[] = {0x10, 0x20, 0x30, 0x40, 0x50, 0x70, 0xA0, 0xE0};
static const Bit8u MODE_0_LPF_AMP = 0x80;
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 above in the new model implementation
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 Bit8u MODE_1_COMB_FACTOR[] = {0x90, 0x60, 0x60, 0x60};
static const Bit8u 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 Bit8u MODE_1_DRY_AMP[] = {0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80};
static const Bit8u MODE_1_WET_AMP[] = {0x10, 0x20, 0x30, 0x40, 0x50, 0x70, 0xA0, 0xE0};
static const Bit8u MODE_1_LPF_AMP = 0x80;
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 above in the new model implementation
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 Bit8u MODE_2_COMB_FACTOR[] = {0, 0x60, 0x60, 0x60};
static const Bit8u MODE_2_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 Bit8u MODE_2_DRY_AMP[] = {0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80};
static const Bit8u MODE_2_WET_AMP[] = {0x10, 0x20, 0x30, 0x40, 0x50, 0x70, 0xA0, 0xE0};
static const Bit8u 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 Bit8u MODE_3_COMB_FACTOR[] = {0x68};
static const Bit8u MODE_3_COMB_FEEDBACK[] = {0x68, 0x60};
static const Bit8u MODE_3_DRY_AMP[] = {0x10, 0x10, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
0x10, 0x20, 0x20, 0x10, 0x20, 0x10, 0x20, 0x10};
static const Bit8u MODE_3_WET_AMP[] = {0x08, 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};
return *REVERB_SETTINGS[mode];
}
static inline IntSample weirdMul(IntSample sample, Bit8u addMask, Bit8u carryMask) {
#if MT32EMU_BOSS_REVERB_PRECISE_MODE
// This algorithm tries to emulate exactly Boss multiplication operation (at least this is what we see on reverb RAM data lines).
Bit8u mask = 0x80;
IntSampleEx res = 0;
for (int i = 0; i < 8; i++) {
IntSampleEx carry = (sample < 0) && (mask & carryMask) > 0 ? sample & 1 : 0;
sample >>= 1;
res += (mask & addMask) > 0 ? sample + carry : 0;
mask >>= 1;
}
return IntSample(res);
#else
(void)carryMask;
return IntSample((IntSampleEx(sample) * addMask) >> 8);
#endif
}
static inline FloatSample weirdMul(FloatSample sample, Bit8u addMask, Bit8u carryMask) {
(void)carryMask;
return sample * addMask / 256.0f;
}
static inline IntSample halveSample(IntSample sample) {
return sample >> 1;
}
static inline FloatSample halveSample(FloatSample sample) {
return 0.5f * sample;
}
static inline IntSample quarterSample(IntSample sample) {
#if MT32EMU_BOSS_REVERB_PRECISE_MODE
return (sample >> 1) / 2;
#else
return sample >> 2;
#endif
}
static inline FloatSample quarterSample(FloatSample sample) {
return 0.25f * sample;
}
static inline IntSample addDCBias(IntSample sample) {
return sample;
}
static inline FloatSample addDCBias(FloatSample sample) {
return sample + BIAS;
}
static inline IntSample addAllpassNoise(IntSample sample) {
#if MT32EMU_BOSS_REVERB_PRECISE_MODE
// This introduces reverb noise which actually makes output from the real Boss chip nondeterministic
return sample - 1;
#else
return sample;
#endif
}
static inline FloatSample addAllpassNoise(FloatSample sample) {
return sample;
}
/* NOTE:
* Thanks to Mok for discovering, the adder in BOSS reverb chip is found to perform addition with saturation to avoid integer overflow.
* Analysing of the algorithm suggests that the overflow is most probable when the combs output is added below.
* So, despite this isn't actually accurate, we only add the check here for performance reasons.
*/
static inline IntSample mixCombs(IntSample out1, IntSample out2, IntSample out3) {
#if MT32EMU_BOSS_REVERB_PRECISE_MODE
return Synth::clipSampleEx(Synth::clipSampleEx(Synth::clipSampleEx(Synth::clipSampleEx(IntSampleEx(out1) + (IntSampleEx(out1) >> 1)) + IntSampleEx(out2)) + (IntSampleEx(out2) >> 1)) + IntSampleEx(out3));
#else
return Synth::clipSampleEx(IntSampleEx(out1) + (IntSampleEx(out1) >> 1) + IntSampleEx(out2) + (IntSampleEx(out2) >> 1) + IntSampleEx(out3));
#endif
}
static inline FloatSample mixCombs(FloatSample out1, FloatSample out2, FloatSample out3) {
return 1.5f * (out1 + out2) + out3;
}
template <class Sample>
class RingBuffer {
static inline Sample sampleValueThreshold();
protected:
Sample *buffer;
const Bit32u size;
Bit32u index;
public:
RingBuffer(const Bit32u newsize) : size(newsize), index(0) {
buffer = new Sample[size];
}
virtual ~RingBuffer() {
delete[] buffer;
buffer = NULL;
}
Sample next() {
if (++index >= size) {
index = 0;
}
return buffer[index];
}
bool isEmpty() const {
if (buffer == NULL) return true;
Sample *buf = buffer;
for (Bit32u i = 0; i < size; i++) {
if (*buf < -sampleValueThreshold() || *buf > sampleValueThreshold()) return false;
buf++;
}
return true;
}
void mute() {
Synth::muteSampleBuffer(buffer, size);
}
};
template<>
IntSample RingBuffer<IntSample>::sampleValueThreshold() {
return 8;
}
template<>
FloatSample RingBuffer<FloatSample>::sampleValueThreshold() {
return 0.001f;
}
template <class Sample>
class AllpassFilter : public RingBuffer<Sample> {
public:
AllpassFilter(const Bit32u useSize) : RingBuffer<Sample>(useSize) {}
// This model corresponds to the allpass filter implementation of the real CM-32L device
// found from sample analysis
Sample process(const Sample in) {
const Sample bufferOut = this->next();
// store input - feedback / 2
this->buffer[this->index] = in - halveSample(bufferOut);
// return buffer output + feedforward / 2
return bufferOut + halveSample(this->buffer[this->index]);
}
};
template <class Sample>
class CombFilter : public RingBuffer<Sample> {
protected:
const Bit8u filterFactor;
Bit8u feedbackFactor;
public:
CombFilter(const Bit32u useSize, const Bit8u useFilterFactor) : RingBuffer<Sample>(useSize), filterFactor(useFilterFactor) {}
// This model corresponds to the comb filter implementation of the real CM-32L device
void process(const Sample in) {
// the previously stored value
const Sample last = this->buffer[this->index];
// prepare input + feedback
const Sample filterIn = in + weirdMul(this->next(), feedbackFactor, 0xF0);
// store input + feedback processed by a low-pass filter
this->buffer[this->index] = weirdMul(last, filterFactor, 0xC0) - filterIn;
}
Sample getOutputAt(const Bit32u outIndex) const {
return this->buffer[(this->size + this->index - outIndex) % this->size];
}
void setFeedbackFactor(const Bit8u useFeedbackFactor) {
feedbackFactor = useFeedbackFactor;
}
};
template <class Sample>
class DelayWithLowPassFilter : public CombFilter<Sample> {
Bit8u amp;
public:
DelayWithLowPassFilter(const Bit32u useSize, const Bit8u useFilterFactor, const Bit8u useAmp)
: CombFilter<Sample>(useSize, useFilterFactor), amp(useAmp) {}
void process(const Sample in) {
// the previously stored value
const Sample last = this->buffer[this->index];
// move to the next index
this->next();
// low-pass filter process
Sample lpfOut = weirdMul(last, this->filterFactor, 0xFF) + in;
// store lpfOut multiplied by LPF amp factor
this->buffer[this->index] = weirdMul(lpfOut, amp, 0xFF);
}
};
template <class Sample>
class TapDelayCombFilter : public CombFilter<Sample> {
Bit32u outL;
Bit32u outR;
public:
TapDelayCombFilter(const Bit32u useSize, const Bit8u useFilterFactor) : CombFilter<Sample>(useSize, useFilterFactor) {}
void process(const Sample in) {
// the previously stored value
const Sample last = this->buffer[this->index];
// move to the next index
this->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
const Sample filterIn = in + weirdMul(this->getOutputAt(outR + MODE_3_FEEDBACK_DELAY), this->feedbackFactor, 0xF0);
// store input + feedback processed by a low-pass filter
this->buffer[this->index] = weirdMul(last, this->filterFactor, 0xF0) - filterIn;
}
Sample getLeftOutput() const {
return this->getOutputAt(outL + PROCESS_DELAY + MODE_3_ADDITIONAL_DELAY);
}
Sample getRightOutput() const {
return this->getOutputAt(outR + PROCESS_DELAY + MODE_3_ADDITIONAL_DELAY);
}
void setOutputPositions(const Bit32u useOutL, const Bit32u useOutR) {
outL = useOutL;
outR = useOutR;
}
};
template <class Sample>
class BReverbModelImpl : public BReverbModel {
public:
AllpassFilter<Sample> **allpasses;
CombFilter<Sample> **combs;
const BReverbSettings &currentSettings;
const bool tapDelayMode;
Bit8u dryAmp;
Bit8u wetLevel;
BReverbModelImpl(const ReverbMode mode, const bool mt32CompatibleModel) :
allpasses(NULL), combs(NULL),
currentSettings(mt32CompatibleModel ? getMT32Settings(mode) : getCM32L_LAPCSettings(mode)),
tapDelayMode(mode == REVERB_MODE_TAP_DELAY)
{}
~BReverbModelImpl() {
close();
}
bool isOpen() const {
return combs != NULL;
}
void open() {
if (isOpen()) return;
if (currentSettings.numberOfAllpasses > 0) {
allpasses = new AllpassFilter<Sample>*[currentSettings.numberOfAllpasses];
for (Bit32u i = 0; i < currentSettings.numberOfAllpasses; i++) {
allpasses[i] = new AllpassFilter<Sample>(currentSettings.allpassSizes[i]);
}
}
combs = new CombFilter<Sample>*[currentSettings.numberOfCombs];
if (tapDelayMode) {
*combs = new TapDelayCombFilter<Sample>(*currentSettings.combSizes, *currentSettings.filterFactors);
} else {
combs[0] = new DelayWithLowPassFilter<Sample>(currentSettings.combSizes[0], currentSettings.filterFactors[0], currentSettings.lpfAmp);
for (Bit32u i = 1; i < currentSettings.numberOfCombs; i++) {
combs[i] = new CombFilter<Sample>(currentSettings.combSizes[i], currentSettings.filterFactors[i]);
}
}
mute();
}
void 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 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 setParameters(Bit8u time, Bit8u level) {
if (!isOpen()) return;
level &= 7;
time &= 7;
if (tapDelayMode) {
TapDelayCombFilter<Sample> *comb = static_cast<TapDelayCombFilter<Sample> *> (*combs);
comb->setOutputPositions(currentSettings.outLPositions[time], currentSettings.outRPositions[time & 7]);
comb->setFeedbackFactor(currentSettings.feedbackFactors[((level < 3) || (time < 6)) ? 0 : 1]);
} else {
for (Bit32u i = 1; i < currentSettings.numberOfCombs; i++) {
combs[i]->setFeedbackFactor(currentSettings.feedbackFactors[(i << 3) + time]);
}
}
if (time == 0 && level == 0) {
dryAmp = wetLevel = 0;
} else {
if (tapDelayMode && ((time == 0) || (time == 1 && level == 1))) {
// Looks like MT-32 implementation has some minor quirks in this mode:
// for odd level values, the output level changes sometimes depending on the time value which doesn't seem right.
dryAmp = currentSettings.dryAmps[level + 8];
} else {
dryAmp = currentSettings.dryAmps[level];
}
wetLevel = currentSettings.wetLevels[level];
}
}
bool isActive() const {
if (!isOpen()) return false;
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;
}
bool isMT32Compatible(const ReverbMode mode) const {
return &currentSettings == &getMT32Settings(mode);
}
template <class SampleEx>
void produceOutput(const Sample *inLeft, const Sample *inRight, Sample *outLeft, Sample *outRight, Bit32u numSamples) {
if (!isOpen()) {
Synth::muteSampleBuffer(outLeft, numSamples);
Synth::muteSampleBuffer(outRight, numSamples);
return;
}
while ((numSamples--) > 0) {
Sample dry;
if (tapDelayMode) {
dry = halveSample(*(inLeft++)) + halveSample(*(inRight++));
} else {
dry = quarterSample(*(inLeft++)) + quarterSample(*(inRight++));
}
// Looks like dryAmp doesn't change in MT-32 but it does in CM-32L / LAPC-I
dry = weirdMul(addDCBias(dry), dryAmp, 0xFF);
if (tapDelayMode) {
TapDelayCombFilter<Sample> *comb = static_cast<TapDelayCombFilter<Sample> *>(*combs);
comb->process(dry);
if (outLeft != NULL) {
*(outLeft++) = weirdMul(comb->getLeftOutput(), wetLevel, 0xFF);
}
if (outRight != NULL) {
*(outRight++) = weirdMul(comb->getRightOutput(), wetLevel, 0xFF);
}
} else {
DelayWithLowPassFilter<Sample> * const entranceDelay = static_cast<DelayWithLowPassFilter<Sample> *>(combs[0]);
// If the output position is equal to the comb size, get it now in order not to lose it
Sample link = entranceDelay->getOutputAt(currentSettings.combSizes[0] - 1);
// Entrance LPF. Note, comb.process() differs a bit here.
entranceDelay->process(dry);
link = allpasses[0]->process(addAllpassNoise(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 lose it
Sample outL1 = combs[1]->getOutputAt(currentSettings.outLPositions[0] - 1);
combs[1]->process(link);
combs[2]->process(link);
combs[3]->process(link);
if (outLeft != NULL) {
Sample outL2 = combs[2]->getOutputAt(currentSettings.outLPositions[1]);
Sample outL3 = combs[3]->getOutputAt(currentSettings.outLPositions[2]);
Sample outSample = mixCombs(outL1, outL2, outL3);
*(outLeft++) = weirdMul(outSample, wetLevel, 0xFF);
}
if (outRight != NULL) {
Sample outR1 = combs[1]->getOutputAt(currentSettings.outRPositions[0]);
Sample outR2 = combs[2]->getOutputAt(currentSettings.outRPositions[1]);
Sample outR3 = combs[3]->getOutputAt(currentSettings.outRPositions[2]);
Sample outSample = mixCombs(outR1, outR2, outR3);
*(outRight++) = weirdMul(outSample, wetLevel, 0xFF);
}
} // if (tapDelayMode)
} // while ((numSamples--) > 0)
} // produceOutput
bool process(const IntSample *inLeft, const IntSample *inRight, IntSample *outLeft, IntSample *outRight, Bit32u numSamples);
bool process(const FloatSample *inLeft, const FloatSample *inRight, FloatSample *outLeft, FloatSample *outRight, Bit32u numSamples);
};
BReverbModel *BReverbModel::createBReverbModel(const ReverbMode mode, const bool mt32CompatibleModel, const RendererType rendererType) {
switch (rendererType)
{
case RendererType_BIT16S:
return new BReverbModelImpl<IntSample>(mode, mt32CompatibleModel);
case RendererType_FLOAT:
return new BReverbModelImpl<FloatSample>(mode, mt32CompatibleModel);
default:
break;
}
return NULL;
}
template <>
bool BReverbModelImpl<IntSample>::process(const IntSample *inLeft, const IntSample *inRight, IntSample *outLeft, IntSample *outRight, Bit32u numSamples) {
produceOutput<IntSampleEx>(inLeft, inRight, outLeft, outRight, numSamples);
return true;
}
template <>
bool BReverbModelImpl<IntSample>::process(const FloatSample *, const FloatSample *, FloatSample *, FloatSample *, Bit32u) {
return false;
}
template <>
bool BReverbModelImpl<FloatSample>::process(const IntSample *, const IntSample *, IntSample *, IntSample *, Bit32u) {
return false;
}
template <>
bool BReverbModelImpl<FloatSample>::process(const FloatSample *inLeft, const FloatSample *inRight, FloatSample *outLeft, FloatSample *outRight, Bit32u numSamples) {
produceOutput<FloatSample>(inLeft, inRight, outLeft, outRight, numSamples);
return true;
}
} // namespace MT32Emu
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