1 /***************************************************************************
\r
4 begin : Wed May 15 2002
\r
5 copyright : (C) 2002 by Pete Bernert
\r
6 email : BlackDove@addcom.de
\r
7 ***************************************************************************/
\r
8 /***************************************************************************
\r
10 * This program is free software; you can redistribute it and/or modify *
\r
11 * it under the terms of the GNU General Public License as published by *
\r
12 * the Free Software Foundation; either version 2 of the License, or *
\r
13 * (at your option) any later version. See also the license.txt file for *
\r
14 * additional informations. *
\r
16 ***************************************************************************/
\r
22 // will be included from spu.c
\r
25 ////////////////////////////////////////////////////////////////////////
\r
27 ////////////////////////////////////////////////////////////////////////
\r
29 unsigned long RateTable[160];
\r
31 void InitADSR(void) // INIT ADSR
\r
33 unsigned long r,rs,rd;int i;
\r
35 memset(RateTable,0,sizeof(unsigned long)*160); // build the rate table according to Neill's rules (see at bottom of file)
\r
39 for(i=32;i<160;i++) // we start at pos 32 with the real values... everything before is 0
\r
44 rd++;if(rd==5) {rd=1;rs*=2;}
\r
46 if(r>0x3FFFFFFF) r=0x3FFFFFFF;
\r
52 ////////////////////////////////////////////////////////////////////////
\r
54 INLINE void StartADSR(int ch) // MIX ADSR
\r
56 s_chan[ch].ADSRX.lVolume=1; // and init some adsr vars
\r
57 s_chan[ch].ADSRX.State=0;
\r
58 s_chan[ch].ADSRX.EnvelopeVol=0;
\r
61 ////////////////////////////////////////////////////////////////////////
\r
63 INLINE int MixADSR(int ch) // MIX ADSR
\r
65 if(s_chan[ch].bStop) // should be stopped:
\r
67 if(s_chan[ch].ADSRX.ReleaseModeExp)
\r
69 switch((s_chan[ch].ADSRX.EnvelopeVol>>28)&0x7)
\r
71 case 0: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x18 +0 + 32]; break;
\r
72 case 1: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x18 +4 + 32]; break;
\r
73 case 2: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x18 +6 + 32]; break;
\r
74 case 3: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x18 +8 + 32]; break;
\r
75 case 4: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x18 +9 + 32]; break;
\r
76 case 5: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x18 +10+ 32]; break;
\r
77 case 6: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x18 +11+ 32]; break;
\r
78 case 7: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x18 +12+ 32]; break;
\r
83 s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.ReleaseRate^0x1F))-0x0C + 32];
\r
86 if(s_chan[ch].ADSRX.EnvelopeVol<0)
\r
88 s_chan[ch].ADSRX.EnvelopeVol=0;
\r
89 // don't stop if this chan can still cause irqs
\r
90 if(!(spuCtrl&0x40) || (s_chan[ch].pCurr > pSpuIrq && s_chan[ch].pLoop > pSpuIrq))
\r
92 s_chan[ch].pCurr=(unsigned char *)-1;
\r
93 //s_chan[ch].bReverb=0;
\r
94 //s_chan[ch].bNoise=0;
\r
97 s_chan[ch].ADSRX.lVolume=s_chan[ch].ADSRX.EnvelopeVol>>21;
\r
98 return s_chan[ch].ADSRX.lVolume;
\r
100 else // not stopped yet?
\r
102 if(s_chan[ch].ADSRX.State==0) // -> attack
\r
104 if(s_chan[ch].ADSRX.AttackModeExp)
\r
106 if(s_chan[ch].ADSRX.EnvelopeVol<0x60000000)
\r
107 s_chan[ch].ADSRX.EnvelopeVol+=RateTable[(s_chan[ch].ADSRX.AttackRate^0x7F)-0x10 + 32];
\r
109 s_chan[ch].ADSRX.EnvelopeVol+=RateTable[(s_chan[ch].ADSRX.AttackRate^0x7F)-0x18 + 32];
\r
113 s_chan[ch].ADSRX.EnvelopeVol+=RateTable[(s_chan[ch].ADSRX.AttackRate^0x7F)-0x10 + 32];
\r
116 if(s_chan[ch].ADSRX.EnvelopeVol<0)
\r
118 s_chan[ch].ADSRX.EnvelopeVol=0x7FFFFFFF;
\r
119 s_chan[ch].ADSRX.State=1;
\r
122 s_chan[ch].ADSRX.lVolume=s_chan[ch].ADSRX.EnvelopeVol>>21;
\r
123 return s_chan[ch].ADSRX.lVolume;
\r
125 //--------------------------------------------------//
\r
126 if(s_chan[ch].ADSRX.State==1) // -> decay
\r
128 switch((s_chan[ch].ADSRX.EnvelopeVol>>28)&0x7)
\r
130 case 0: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.DecayRate^0x1F))-0x18+0 + 32]; break;
\r
131 case 1: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.DecayRate^0x1F))-0x18+4 + 32]; break;
\r
132 case 2: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.DecayRate^0x1F))-0x18+6 + 32]; break;
\r
133 case 3: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.DecayRate^0x1F))-0x18+8 + 32]; break;
\r
134 case 4: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.DecayRate^0x1F))-0x18+9 + 32]; break;
\r
135 case 5: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.DecayRate^0x1F))-0x18+10+ 32]; break;
\r
136 case 6: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.DecayRate^0x1F))-0x18+11+ 32]; break;
\r
137 case 7: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[(4*(s_chan[ch].ADSRX.DecayRate^0x1F))-0x18+12+ 32]; break;
\r
140 if(s_chan[ch].ADSRX.EnvelopeVol<0) s_chan[ch].ADSRX.EnvelopeVol=0;
\r
141 if(((s_chan[ch].ADSRX.EnvelopeVol>>27)&0xF) <= s_chan[ch].ADSRX.SustainLevel)
\r
143 s_chan[ch].ADSRX.State=2;
\r
146 s_chan[ch].ADSRX.lVolume=s_chan[ch].ADSRX.EnvelopeVol>>21;
\r
147 return s_chan[ch].ADSRX.lVolume;
\r
149 //--------------------------------------------------//
\r
150 if(s_chan[ch].ADSRX.State==2) // -> sustain
\r
152 if(s_chan[ch].ADSRX.SustainIncrease)
\r
154 if(s_chan[ch].ADSRX.SustainModeExp)
\r
156 if(s_chan[ch].ADSRX.EnvelopeVol<0x60000000)
\r
157 s_chan[ch].ADSRX.EnvelopeVol+=RateTable[(s_chan[ch].ADSRX.SustainRate^0x7F)-0x10 + 32];
\r
159 s_chan[ch].ADSRX.EnvelopeVol+=RateTable[(s_chan[ch].ADSRX.SustainRate^0x7F)-0x18 + 32];
\r
163 s_chan[ch].ADSRX.EnvelopeVol+=RateTable[(s_chan[ch].ADSRX.SustainRate^0x7F)-0x10 + 32];
\r
166 if(s_chan[ch].ADSRX.EnvelopeVol<0)
\r
168 s_chan[ch].ADSRX.EnvelopeVol=0x7FFFFFFF;
\r
173 if(s_chan[ch].ADSRX.SustainModeExp)
\r
175 switch((s_chan[ch].ADSRX.EnvelopeVol>>28)&0x7)
\r
177 case 0: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x1B +0 + 32];break;
\r
178 case 1: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x1B +4 + 32];break;
\r
179 case 2: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x1B +6 + 32];break;
\r
180 case 3: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x1B +8 + 32];break;
\r
181 case 4: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x1B +9 + 32];break;
\r
182 case 5: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x1B +10+ 32];break;
\r
183 case 6: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x1B +11+ 32];break;
\r
184 case 7: s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x1B +12+ 32];break;
\r
189 s_chan[ch].ADSRX.EnvelopeVol-=RateTable[((s_chan[ch].ADSRX.SustainRate^0x7F))-0x0F + 32];
\r
192 if(s_chan[ch].ADSRX.EnvelopeVol<0)
\r
194 s_chan[ch].ADSRX.EnvelopeVol=0;
\r
197 s_chan[ch].ADSRX.lVolume=s_chan[ch].ADSRX.EnvelopeVol>>21;
\r
198 return s_chan[ch].ADSRX.lVolume;
\r
207 James Higgs ADSR investigations:
\r
209 PSX SPU Envelope Timings
\r
210 ~~~~~~~~~~~~~~~~~~~~~~~~
\r
212 First, here is an extract from doomed's SPU doc, which explains the basics
\r
213 of the SPU "volume envelope":
\r
215 *** doomed doc extract start ***
\r
217 --------------------------------------------------------------------------
\r
219 --------------------------------------------------------------------------
\r
220 The SPU has 24 hardware voices. These voices can be used to reproduce sample
\r
221 data, noise or can be used as frequency modulator on the next voice.
\r
222 Each voice has it's own programmable ADSR envelope filter. The main volume
\r
223 can be programmed independently for left and right output.
\r
225 The ADSR envelope filter works as follows:
\r
226 Ar = Attack rate, which specifies the speed at which the volume increases
\r
227 from zero to it's maximum value, as soon as the note on is given. The
\r
228 slope can be set to lineair or exponential.
\r
229 Dr = Decay rate specifies the speed at which the volume decreases to the
\r
230 sustain level. Decay is always decreasing exponentially.
\r
231 Sl = Sustain level, base level from which sustain starts.
\r
232 Sr = Sustain rate is the rate at which the volume of the sustained note
\r
233 increases or decreases. This can be either lineair or exponential.
\r
234 Rr = Release rate is the rate at which the volume of the note decreases
\r
235 as soon as the note off is given.
\r
239 Sl _| _ / _ \__--- \
\r
243 |/___________________\________
\r
246 The overal volume can also be set to sweep up or down lineairly or
\r
247 exponentially from it's current value. This can be done seperately
\r
248 for left and right.
\r
250 Relevant SPU registers:
\r
251 -------------------------------------------------------------
\r
252 $1f801xx8 Attack/Decay/Sustain level
\r
253 bit |0f|0e 0d 0c 0b 0a 09 08|07 06 05 04|03 02 01 00|
\r
254 desc.|Am| Ar |Dr |Sl |
\r
256 Am 0 Attack mode Linear
\r
259 Ar 0-7f attack rate
\r
261 Sl 0-f sustain level
\r
262 -------------------------------------------------------------
\r
263 $1f801xxa Sustain rate, Release Rate.
\r
264 bit |0f|0e|0d|0c 0b 0a 09 08 07 06|05|04 03 02 01 00|
\r
265 desc.|Sm|Sd| 0| Sr |Rm|Rr |
\r
267 Sm 0 sustain rate mode linear
\r
269 Sd 0 sustain rate mode increase
\r
271 Sr 0-7f Sustain Rate
\r
272 Rm 0 Linear decrease
\r
273 1 Exponential decrease
\r
274 Rr 0-1f Release Rate
\r
276 Note: decay mode is always Expontial decrease, and thus cannot
\r
278 -------------------------------------------------------------
\r
279 $1f801xxc Current ADSR volume
\r
280 bit |0f 0e 0d 0c 0b 0a 09 08 07 06 05 04 03 02 01 00|
\r
283 ADSRvol Returns the current envelope volume when
\r
285 -- James' Note: return range: 0 -> 32767
\r
287 *** doomed doc extract end ***
\r
289 By using a small PSX proggie to visualise the envelope as it was played,
\r
290 the following results for envelope timing were obtained:
\r
292 1. Attack rate value (linear mode)
\r
294 Attack value range: 0 -> 127
\r
296 Value | 48 | 52 | 56 | 60 | 64 | 68 | 72 | | 80 |
\r
297 -----------------------------------------------------------------
\r
298 Frames | 11 | 21 | 42 | 84 | 169| 338| 676| |2890|
\r
300 Note: frames is no. of PAL frames to reach full volume (100%
\r
303 Hmm, noticing that the time taken to reach full volume doubles
\r
304 every time we add 4 to our attack value, we know the equation is
\r
306 frames = k * 2 ^ (value / 4)
\r
308 (You may ponder about envelope generator hardware at this point,
\r
311 By substituting some stuff and running some checks, we get:
\r
313 k = 0.00257 (close enuf)
\r
316 frames = 0.00257 * 2 ^ (value / 4)
\r
317 If you just happen to be writing an emulator, then you can probably
\r
318 use an equation like:
\r
320 %volume_increase_per_tick = 1 / frames
\r
323 ------------------------------------
\r
325 ms=((1<<(value>>2))*514)/10000
\r
326 ------------------------------------
\r
328 2. Decay rate value (only has log mode)
\r
330 Decay value range: 0 -> 15
\r
332 Value | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
\r
333 ------------------------------------------------
\r
334 frames | | | | | 6 | 12 | 24 | 47 |
\r
336 Note: frames here is no. of PAL frames to decay to 50% volume.
\r
338 formula: frames = k * 2 ^ (value)
\r
340 Substituting, we get: k = 0.00146
\r
342 Further info on logarithmic nature:
\r
343 frames to decay to sustain level 3 = 3 * frames to decay to
\r
346 Also no. of frames to 25% volume = roughly 1.85 * no. of frames to
\r
349 Frag it - just use linear approx.
\r
351 ------------------------------------
\r
353 ms=((1<<value)*292)/10000
\r
354 ------------------------------------
\r
357 3. Sustain rate value (linear mode)
\r
359 Sustain rate range: 0 -> 127
\r
361 Value | 48 | 52 | 56 | 60 | 64 | 68 | 72 |
\r
362 -------------------------------------------
\r
363 frames | 9 | 19 | 37 | 74 | 147| 293| 587|
\r
365 Here, frames = no. of PAL frames for volume amplitude to go from 100%
\r
366 to 0% (or vice-versa).
\r
368 Same formula as for attack value, just a different value for k:
\r
372 ie: frames = 0.00225 * 2 ^ (value / 4)
\r
374 For emulation purposes:
\r
376 %volume_increase_or_decrease_per_tick = 1 / frames
\r
378 ------------------------------------
\r
380 ms=((1<<(value>>2))*450)/10000
\r
381 ------------------------------------
\r
384 4. Release rate (linear mode)
\r
386 Release rate range: 0 -> 31
\r
388 Value | 13 | 14 | 15 | 16 | 17 |
\r
389 ---------------------------------------------------------------
\r
390 frames | 18 | 36 | 73 | 146| 292|
\r
392 Here, frames = no. of PAL frames to decay from 100% vol to 0% vol
\r
393 after "note-off" is triggered.
\r
395 Formula: frames = k * 2 ^ (value)
\r
397 And so: k = 0.00223
\r
399 ------------------------------------
\r
401 ms=((1<<value)*446)/10000
\r
402 ------------------------------------
\r
407 Log stuff not figured out. You may get some clues from the "Decay rate"
\r
408 stuff above. For emu purposes it may not be important - use linear
\r
411 To get timings in millisecs, multiply frames by 20.
\r
415 - James Higgs 17/6/2000
\r
416 james7780@yahoo.com
\r
418 //---------------------------------------------------------------
\r
420 OLD adsr mixing according to james' rules... has to be called
\r
421 every one millisecond
\r
424 long v,v2,lT,l1,l2,l3;
\r
426 if(s_chan[ch].bStop) // psx wants to stop? -> release phase
\r
428 if(s_chan[ch].ADSR.ReleaseVal!=0) // -> release not 0: do release (if 0: stop right now)
\r
430 if(!s_chan[ch].ADSR.ReleaseVol) // --> release just started? set up the release stuff
\r
432 s_chan[ch].ADSR.ReleaseStartTime=s_chan[ch].ADSR.lTime;
\r
433 s_chan[ch].ADSR.ReleaseVol=s_chan[ch].ADSR.lVolume;
\r
434 s_chan[ch].ADSR.ReleaseTime = // --> calc how long does it take to reach the wanted sus level
\r
435 (s_chan[ch].ADSR.ReleaseTime*
\r
436 s_chan[ch].ADSR.ReleaseVol)/1024;
\r
438 // -> NO release exp mode used (yet)
\r
439 v=s_chan[ch].ADSR.ReleaseVol; // -> get last volume
\r
440 lT=s_chan[ch].ADSR.lTime- // -> how much time is past?
\r
441 s_chan[ch].ADSR.ReleaseStartTime;
\r
442 l1=s_chan[ch].ADSR.ReleaseTime;
\r
444 if(lT<l1) // -> we still have to release
\r
446 v=v-((v*lT)/l1); // --> calc new volume
\r
448 else // -> release is over: now really stop that sample
\r
449 {v=0;s_chan[ch].bOn=0;s_chan[ch].ADSR.ReleaseVol=0;s_chan[ch].bNoise=0;}
\r
451 else // -> release IS 0: release at once
\r
453 v=0;s_chan[ch].bOn=0;s_chan[ch].ADSR.ReleaseVol=0;s_chan[ch].bNoise=0;
\r
457 {//--------------------------------------------------// not in release phase:
\r
459 lT=s_chan[ch].ADSR.lTime;
\r
460 l1=s_chan[ch].ADSR.AttackTime;
\r
462 if(lT<l1) // attack
\r
463 { // no exp mode used (yet)
\r
464 // if(s_chan[ch].ADSR.AttackModeExp)
\r
475 { // should be exp, but who cares? ;)
\r
476 l2=s_chan[ch].ADSR.DecayTime;
\r
477 v2=s_chan[ch].ADSR.SustainLevel;
\r
482 v-=(((v-v2)*lT)/l2);
\r
485 { // no exp mode used (yet)
\r
486 l3=s_chan[ch].ADSR.SustainTime;
\r
488 if(s_chan[ch].ADSR.SustainModeDec>0)
\r
490 if(l3!=0) v2+=((v-v2)*lT)/l3;
\r
495 if(l3!=0) v2-=(v2*lT)/l3;
\r
500 if(v2<=0) {v2=0;s_chan[ch].bOn=0;s_chan[ch].ADSR.ReleaseVol=0;s_chan[ch].bNoise=0;}
\r
507 //----------------------------------------------------//
\r
508 // ok, done for this channel, so increase time
\r
510 s_chan[ch].ADSR.lTime+=1; // 1 = 1.020408f ms;
\r
512 if(v>1024) v=1024; // adjust volume
\r
514 s_chan[ch].ADSR.lVolume=v; // store act volume
\r
516 return v; // return the volume factor
\r
520 //-----------------------------------------------------------------------------
\r
521 //-----------------------------------------------------------------------------
\r
522 //-----------------------------------------------------------------------------
\r
526 -----------------------------------------------------------------------------
\r
528 Playstation SPU envelope timing notes
\r
529 -----------------------------------------------------------------------------
\r
531 This is preliminary. This may be wrong. But the model described herein fits
\r
532 all of my experimental data, and it's just simple enough to sound right.
\r
534 ADSR envelope level ranges from 0x00000000 to 0x7FFFFFFF internally.
\r
535 The value returned by channel reg 0xC is (envelope_level>>16).
\r
537 Each sample, an increment or decrement value will be added to or
\r
538 subtracted from this envelope level.
\r
540 Create the rate log table. The values double every 4 entries.
\r
547 entry #40 = 4096...
\r
548 entry #44 = 8192...
\r
549 entry #48 = 16384...
\r
550 entry #52 = 32768...
\r
551 entry #56 = 65536...
\r
553 increments and decrements are in terms of ratelogtable[n]
\r
554 n may exceed the table bounds (plan on n being between -32 and 127).
\r
555 table values are all clipped between 0x00000000 and 0x3FFFFFFF
\r
557 when you "voice on", the envelope is always fully reset.
\r
558 (yes, it may click. the real thing does this too.)
\r
560 envelope level begins at zero.
\r
562 each state happens for at least 1 cycle
\r
563 (transitions are not instantaneous)
\r
564 this may result in some oddness: if the decay rate is uberfast, it will cut
\r
565 the envelope from full down to half in one sample, potentially skipping over
\r
570 - if the envelope level has overflowed past the max, clip to 0x7FFFFFFF and
\r
573 Linear attack mode:
\r
574 - line extends upward to 0x7FFFFFFF
\r
575 - increment per sample is ratelogtable[(Ar^0x7F)-0x10]
\r
577 Logarithmic attack mode:
\r
578 if envelope_level < 0x60000000:
\r
579 - line extends upward to 0x60000000
\r
580 - increment per sample is ratelogtable[(Ar^0x7F)-0x10]
\r
582 - line extends upward to 0x7FFFFFFF
\r
583 - increment per sample is ratelogtable[(Ar^0x7F)-0x18]
\r
587 - if ((envelope_level>>27)&0xF) <= Sl, proceed to SUSTAIN.
\r
588 Do not clip to the sustain level.
\r
589 - current line ends at (envelope_level & 0x07FFFFFF)
\r
590 - decrement per sample depends on (envelope_level>>28)&0x7
\r
591 0: ratelogtable[(4*(Dr^0x1F))-0x18+0]
\r
592 1: ratelogtable[(4*(Dr^0x1F))-0x18+4]
\r
593 2: ratelogtable[(4*(Dr^0x1F))-0x18+6]
\r
594 3: ratelogtable[(4*(Dr^0x1F))-0x18+8]
\r
595 4: ratelogtable[(4*(Dr^0x1F))-0x18+9]
\r
596 5: ratelogtable[(4*(Dr^0x1F))-0x18+10]
\r
597 6: ratelogtable[(4*(Dr^0x1F))-0x18+11]
\r
598 7: ratelogtable[(4*(Dr^0x1F))-0x18+12]
\r
599 (note that this is the same as the release rate formula, except that
\r
600 decay rates 10-1F aren't possible... those would be slower in theory)
\r
604 - no terminating condition except for voice off
\r
605 - Sd=0 (increase) behavior is identical to ATTACK for both log and linear.
\r
606 - Sd=1 (decrease) behavior:
\r
607 Linear sustain decrease:
\r
608 - line extends to 0x00000000
\r
609 - decrement per sample is ratelogtable[(Sr^0x7F)-0x0F]
\r
610 Logarithmic sustain decrease:
\r
611 - current line ends at (envelope_level & 0x07FFFFFF)
\r
612 - decrement per sample depends on (envelope_level>>28)&0x7
\r
613 0: ratelogtable[(Sr^0x7F)-0x1B+0]
\r
614 1: ratelogtable[(Sr^0x7F)-0x1B+4]
\r
615 2: ratelogtable[(Sr^0x7F)-0x1B+6]
\r
616 3: ratelogtable[(Sr^0x7F)-0x1B+8]
\r
617 4: ratelogtable[(Sr^0x7F)-0x1B+9]
\r
618 5: ratelogtable[(Sr^0x7F)-0x1B+10]
\r
619 6: ratelogtable[(Sr^0x7F)-0x1B+11]
\r
620 7: ratelogtable[(Sr^0x7F)-0x1B+12]
\r
624 - if the envelope level has overflowed to negative, clip to 0 and QUIT.
\r
626 Linear release mode:
\r
627 - line extends to 0x00000000
\r
628 - decrement per sample is ratelogtable[(4*(Rr^0x1F))-0x0C]
\r
630 Logarithmic release mode:
\r
631 - line extends to (envelope_level & 0x0FFFFFFF)
\r
632 - decrement per sample depends on (envelope_level>>28)&0x7
\r
633 0: ratelogtable[(4*(Rr^0x1F))-0x18+0]
\r
634 1: ratelogtable[(4*(Rr^0x1F))-0x18+4]
\r
635 2: ratelogtable[(4*(Rr^0x1F))-0x18+6]
\r
636 3: ratelogtable[(4*(Rr^0x1F))-0x18+8]
\r
637 4: ratelogtable[(4*(Rr^0x1F))-0x18+9]
\r
638 5: ratelogtable[(4*(Rr^0x1F))-0x18+10]
\r
639 6: ratelogtable[(4*(Rr^0x1F))-0x18+11]
\r
640 7: ratelogtable[(4*(Rr^0x1F))-0x18+12]
\r
642 -----------------------------------------------------------------------------
\r