aboutsummaryrefslogtreecommitdiff
path: root/audio/softsynth/mt32/TVA.cpp
blob: 3f7064f9a4374d259ea6cdf72a5c7dffa2afef1d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
/* Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009 Dean Beeler, Jerome Fisher
 * Copyright (C) 2011-2017 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/>.
 */

/*
 * This class emulates the calculations performed by the 8095 microcontroller in order to configure the LA-32's amplitude ramp for a single partial at each stage of its TVA envelope.
 * Unless we introduced bugs, it should be pretty much 100% accurate according to Mok's specifications.
*/

#include "internals.h"

#include "TVA.h"
#include "Part.h"
#include "Partial.h"
#include "Poly.h"
#include "Synth.h"
#include "Tables.h"

namespace MT32Emu {

// CONFIRMED: Matches a table in ROM - haven't got around to coming up with a formula for it yet.
static Bit8u biasLevelToAmpSubtractionCoeff[13] = {255, 187, 137, 100, 74, 54, 40, 29, 21, 15, 10, 5, 0};

TVA::TVA(const Partial *usePartial, LA32Ramp *useAmpRamp) :
	partial(usePartial), ampRamp(useAmpRamp), system(&usePartial->getSynth()->mt32ram.system), phase(TVA_PHASE_DEAD) {
}

void TVA::startRamp(Bit8u newTarget, Bit8u newIncrement, int newPhase) {
	target = newTarget;
	phase = newPhase;
	ampRamp->startRamp(newTarget, newIncrement);
#if MT32EMU_MONITOR_TVA >= 1
	partial->getSynth()->printDebug("[+%lu] [Partial %d] TVA,ramp,%x,%s%x,%d", partial->debugGetSampleNum(), partial->debugGetPartialNum(), newTarget, (newIncrement & 0x80) ? "-" : "+", (newIncrement & 0x7F), newPhase);
#endif
}

void TVA::end(int newPhase) {
	phase = newPhase;
	playing = false;
#if MT32EMU_MONITOR_TVA >= 1
	partial->getSynth()->printDebug("[+%lu] [Partial %d] TVA,end,%d", partial->debugGetSampleNum(), partial->debugGetPartialNum(), newPhase);
#endif
}

static int multBias(Bit8u biasLevel, int bias) {
	return (bias * biasLevelToAmpSubtractionCoeff[biasLevel]) >> 5;
}

static int calcBiasAmpSubtraction(Bit8u biasPoint, Bit8u biasLevel, int key) {
	if ((biasPoint & 0x40) == 0) {
		int bias = biasPoint + 33 - key;
		if (bias > 0) {
			return multBias(biasLevel, bias);
		}
	} else {
		int bias = biasPoint - 31 - key;
		if (bias < 0) {
			bias = -bias;
			return multBias(biasLevel, bias);
		}
	}
	return 0;
}

static int calcBiasAmpSubtractions(const TimbreParam::PartialParam *partialParam, int key) {
	int biasAmpSubtraction1 = calcBiasAmpSubtraction(partialParam->tva.biasPoint1, partialParam->tva.biasLevel1, key);
	if (biasAmpSubtraction1 > 255) {
		return 255;
	}
	int biasAmpSubtraction2 = calcBiasAmpSubtraction(partialParam->tva.biasPoint2, partialParam->tva.biasLevel2, key);
	if (biasAmpSubtraction2 > 255) {
		return 255;
	}
	int biasAmpSubtraction = biasAmpSubtraction1 + biasAmpSubtraction2;
	if (biasAmpSubtraction > 255) {
		return 255;
	}
	return biasAmpSubtraction;
}

static int calcVeloAmpSubtraction(Bit8u veloSensitivity, unsigned int velocity) {
	// FIXME:KG: Better variable names
	int velocityMult = veloSensitivity - 50;
	int absVelocityMult = velocityMult < 0 ? -velocityMult : velocityMult;
	velocityMult = signed(unsigned(velocityMult * (signed(velocity) - 64)) << 2);
	return absVelocityMult - (velocityMult >> 8); // PORTABILITY NOTE: Assumes arithmetic shift
}

static int calcBasicAmp(const Tables *tables, const Partial *partial, const MemParams::System *system, const TimbreParam::PartialParam *partialParam, const MemParams::PatchTemp *patchTemp, const MemParams::RhythmTemp *rhythmTemp, int biasAmpSubtraction, int veloAmpSubtraction, Bit8u expression, bool hasRingModQuirk) {
	int amp = 155;

	if (!(hasRingModQuirk ? partial->isRingModulatingNoMix() : partial->isRingModulatingSlave())) {
		amp -= tables->masterVolToAmpSubtraction[system->masterVol];
		if (amp < 0) {
			return 0;
		}
		amp -= tables->levelToAmpSubtraction[patchTemp->outputLevel];
		if (amp < 0) {
			return 0;
		}
		amp -= tables->levelToAmpSubtraction[expression];
		if (amp < 0) {
			return 0;
		}
		if (rhythmTemp != NULL) {
			amp -= tables->levelToAmpSubtraction[rhythmTemp->outputLevel];
			if (amp < 0) {
				return 0;
			}
		}
	}
	amp -= biasAmpSubtraction;
	if (amp < 0) {
		return 0;
	}
	amp -= tables->levelToAmpSubtraction[partialParam->tva.level];
	if (amp < 0) {
		return 0;
	}
	amp -= veloAmpSubtraction;
	if (amp < 0) {
		return 0;
	}
	if (amp > 155) {
		amp = 155;
	}
	amp -= partialParam->tvf.resonance >> 1;
	if (amp < 0) {
		return 0;
	}
	return amp;
}

static int calcKeyTimeSubtraction(Bit8u envTimeKeyfollow, int key) {
	if (envTimeKeyfollow == 0) {
		return 0;
	}
	return (key - 60) >> (5 - envTimeKeyfollow); // PORTABILITY NOTE: Assumes arithmetic shift
}

void TVA::reset(const Part *newPart, const TimbreParam::PartialParam *newPartialParam, const MemParams::RhythmTemp *newRhythmTemp) {
	part = newPart;
	partialParam = newPartialParam;
	patchTemp = newPart->getPatchTemp();
	rhythmTemp = newRhythmTemp;

	playing = true;

	const Tables *tables = &Tables::getInstance();

	int key = partial->getPoly()->getKey();
	int velocity = partial->getPoly()->getVelocity();

	keyTimeSubtraction = calcKeyTimeSubtraction(partialParam->tva.envTimeKeyfollow, key);

	biasAmpSubtraction = calcBiasAmpSubtractions(partialParam, key);
	veloAmpSubtraction = calcVeloAmpSubtraction(partialParam->tva.veloSensitivity, velocity);

	int newTarget = calcBasicAmp(tables, partial, system, partialParam, patchTemp, newRhythmTemp, biasAmpSubtraction, veloAmpSubtraction, part->getExpression(), partial->getSynth()->controlROMFeatures->quirkRingModulationNoMix);
	int newPhase;
	if (partialParam->tva.envTime[0] == 0) {
		// Initially go to the TVA_PHASE_ATTACK target amp, and spend the next phase going from there to the TVA_PHASE_2 target amp
		// Note that this means that velocity never affects time for this partial.
		newTarget += partialParam->tva.envLevel[0];
		newPhase = TVA_PHASE_ATTACK; // The first target used in nextPhase() will be TVA_PHASE_2
	} else {
		// Initially go to the base amp determined by TVA level, part volume, etc., and spend the next phase going from there to the full TVA_PHASE_ATTACK target amp.
		newPhase = TVA_PHASE_BASIC; // The first target used in nextPhase() will be TVA_PHASE_ATTACK
	}

	ampRamp->reset();//currentAmp = 0;

	// "Go downward as quickly as possible".
	// Since the current value is 0, the LA32Ramp will notice that we're already at or below the target and trying to go downward,
	// and therefore jump to the target immediately and raise an interrupt.
	startRamp(Bit8u(newTarget), 0x80 | 127, newPhase);
}

void TVA::startAbort() {
	startRamp(64, 0x80 | 127, TVA_PHASE_RELEASE);
}

void TVA::startDecay() {
	if (phase >= TVA_PHASE_RELEASE) {
		return;
	}
	Bit8u newIncrement;
	if (partialParam->tva.envTime[4] == 0) {
		newIncrement = 1;
	} else {
		newIncrement = -partialParam->tva.envTime[4];
	}
	// The next time nextPhase() is called, it will think TVA_PHASE_RELEASE has finished and the partial will be aborted
	startRamp(0, newIncrement, TVA_PHASE_RELEASE);
}

void TVA::handleInterrupt() {
	nextPhase();
}

void TVA::recalcSustain() {
	// We get pinged periodically by the pitch code to recalculate our values when in sustain.
	// This is done so that the TVA will respond to things like MIDI expression and volume changes while it's sustaining, which it otherwise wouldn't do.

	// The check for envLevel[3] == 0 strikes me as slightly dumb. FIXME: Explain why
	if (phase != TVA_PHASE_SUSTAIN || partialParam->tva.envLevel[3] == 0) {
		return;
	}
	// We're sustaining. Recalculate all the values
	const Tables *tables = &Tables::getInstance();
	int newTarget = calcBasicAmp(tables, partial, system, partialParam, patchTemp, rhythmTemp, biasAmpSubtraction, veloAmpSubtraction, part->getExpression(), partial->getSynth()->controlROMFeatures->quirkRingModulationNoMix);
	newTarget += partialParam->tva.envLevel[3];

	// Although we're in TVA_PHASE_SUSTAIN at this point, we cannot be sure that there is no active ramp at the moment.
	// In case the channel volume or the expression changes frequently, the previously started ramp may still be in progress.
	// Real hardware units ignore this possibility and rely on the assumption that the target is the current amp.
	// This is OK in most situations but when the ramp that is currently in progress needs to change direction
	// due to a volume/expression update, this leads to a jump in the amp that is audible as an unpleasant click.
	// To avoid that, we compare the newTarget with the the actual current ramp value and correct the direction if necessary.
	int targetDelta = newTarget - target;

	// Calculate an increment to get to the new amp value in a short, more or less consistent amount of time
	Bit8u newIncrement;
	bool descending = targetDelta < 0;
	if (!descending) {
		newIncrement = tables->envLogarithmicTime[Bit8u(targetDelta)] - 2;
	} else {
		newIncrement = (tables->envLogarithmicTime[Bit8u(-targetDelta)] - 2) | 0x80;
	}
	if (part->getSynth()->isNiceAmpRampEnabled() && (descending != ampRamp->isBelowCurrent(newTarget))) {
		newIncrement ^= 0x80;
	}

	// Configure so that once the transition's complete and nextPhase() is called, we'll just re-enter sustain phase (or decay phase, depending on parameters at the time).
	startRamp(newTarget, newIncrement, TVA_PHASE_SUSTAIN - 1);
}

bool TVA::isPlaying() const {
	return playing;
}

int TVA::getPhase() const {
	return phase;
}

void TVA::nextPhase() {
	const Tables *tables = &Tables::getInstance();

	if (phase >= TVA_PHASE_DEAD || !playing) {
		partial->getSynth()->printDebug("TVA::nextPhase(): Shouldn't have got here with phase %d, playing=%s", phase, playing ? "true" : "false");
		return;
	}
	int newPhase = phase + 1;

	if (newPhase == TVA_PHASE_DEAD) {
		end(newPhase);
		return;
	}

	bool allLevelsZeroFromNowOn = false;
	if (!partial->getSynth()->controlROMFeatures->quirkTVAZeroEnvLevels && partialParam->tva.envLevel[3] == 0) {
		if (newPhase == TVA_PHASE_4) {
			allLevelsZeroFromNowOn = true;
		} else if (partialParam->tva.envLevel[2] == 0) {
			if (newPhase == TVA_PHASE_3) {
				allLevelsZeroFromNowOn = true;
			} else if (partialParam->tva.envLevel[1] == 0) {
				if (newPhase == TVA_PHASE_2) {
					allLevelsZeroFromNowOn = true;
				} else if (partialParam->tva.envLevel[0] == 0) {
					if (newPhase == TVA_PHASE_ATTACK)  { // this line added, missing in ROM - FIXME: Add description of repercussions
						allLevelsZeroFromNowOn = true;
					}
				}
			}
		}
	}

	int newTarget;
	int newIncrement = 0; // Initialised to please compilers
	int envPointIndex = phase;

	if (!allLevelsZeroFromNowOn) {
		newTarget = calcBasicAmp(tables, partial, system, partialParam, patchTemp, rhythmTemp, biasAmpSubtraction, veloAmpSubtraction, part->getExpression(), partial->getSynth()->controlROMFeatures->quirkRingModulationNoMix);

		if (newPhase == TVA_PHASE_SUSTAIN || newPhase == TVA_PHASE_RELEASE) {
			if (partialParam->tva.envLevel[3] == 0) {
				end(newPhase);
				return;
			}
			if (!partial->getPoly()->canSustain()) {
				newPhase = TVA_PHASE_RELEASE;
				newTarget = 0;
				newIncrement = -partialParam->tva.envTime[4];
				if (newIncrement == 0) {
					// We can't let the increment be 0, or there would be no emulated interrupt.
					// So we do an "upward" increment, which should set the amp to 0 extremely quickly
					// and cause an "interrupt" to bring us back to nextPhase().
					newIncrement = 1;
				}
			} else {
				newTarget += partialParam->tva.envLevel[3];
				newIncrement = 0;
			}
		} else {
			newTarget += partialParam->tva.envLevel[envPointIndex];
		}
	} else {
		newTarget = 0;
	}

	if ((newPhase != TVA_PHASE_SUSTAIN && newPhase != TVA_PHASE_RELEASE) || allLevelsZeroFromNowOn) {
		int envTimeSetting = partialParam->tva.envTime[envPointIndex];

		if (newPhase == TVA_PHASE_ATTACK) {
			envTimeSetting -= (signed(partial->getPoly()->getVelocity()) - 64) >> (6 - partialParam->tva.envTimeVeloSensitivity); // PORTABILITY NOTE: Assumes arithmetic shift

			if (envTimeSetting <= 0 && partialParam->tva.envTime[envPointIndex] != 0) {
				envTimeSetting = 1;
			}
		} else {
			envTimeSetting -= keyTimeSubtraction;
		}
		if (envTimeSetting > 0) {
			int targetDelta = newTarget - target;
			if (targetDelta <= 0) {
				if (targetDelta == 0) {
					// target and newTarget are the same.
					// We can't have an increment of 0 or we wouldn't get an emulated interrupt.
					// So instead make the target one less than it really should be and set targetDelta accordingly.
					targetDelta = -1;
					newTarget--;
					if (newTarget < 0) {
						// Oops, newTarget is less than zero now, so let's do it the other way:
						// Make newTarget one more than it really should've been and set targetDelta accordingly.
						// FIXME (apparent bug in real firmware):
						// This means targetDelta will be positive just below here where it's inverted, and we'll end up using envLogarithmicTime[-1], and we'll be setting newIncrement to be descending later on, etc..
						targetDelta = 1;
						newTarget = -newTarget;
					}
				}
				targetDelta = -targetDelta;
				newIncrement = tables->envLogarithmicTime[Bit8u(targetDelta)] - envTimeSetting;
				if (newIncrement <= 0) {
					newIncrement = 1;
				}
				newIncrement = newIncrement | 0x80;
			} else {
				// FIXME: The last 22 or so entries in this table are 128 - surely that fucks things up, since that ends up being -128 signed?
				newIncrement = tables->envLogarithmicTime[Bit8u(targetDelta)] - envTimeSetting;
				if (newIncrement <= 0) {
					newIncrement = 1;
				}
			}
		} else {
			newIncrement = newTarget >= target ? (0x80 | 127) : 127;
		}

		// FIXME: What's the point of this? It's checked or set to non-zero everywhere above
		if (newIncrement == 0) {
			newIncrement = 1;
		}
	}

	startRamp(Bit8u(newTarget), Bit8u(newIncrement), newPhase);
}

} // namespace MT32Emu