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spu: fix some skip accuracy issues
[pcsx_rearmed.git] / plugins / dfsound / adsr.c
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1/***************************************************************************\r
2 adsr.c - description\r
3 -------------------\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
9 * *\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
15 * *\r
16 ***************************************************************************/\r
17\r
18#include "stdafx.h"\r
19\r
20#define _IN_ADSR\r
21\r
22// will be included from spu.c\r
23#ifdef _IN_SPU\r
24\r
25////////////////////////////////////////////////////////////////////////\r
26// ADSR func\r
27////////////////////////////////////////////////////////////////////////\r
28\r
29static int RateTableAdd[128];\r
30static int RateTableSub[128];\r
31\r
32void InitADSR(void) // INIT ADSR\r
33{\r
34 int lcv, denom;\r
35\r
36 // Optimize table - Dr. Hell ADSR math\r
37 for (lcv = 0; lcv < 48; lcv++)\r
38 {\r
39 RateTableAdd[lcv] = (7 - (lcv&3)) << (11 + 16 - (lcv >> 2));\r
40 RateTableSub[lcv] = (-8 + (lcv&3)) << (11 + 16 - (lcv >> 2));\r
41 }\r
42\r
43 for (; lcv < 128; lcv++)\r
44 {\r
45 denom = 1 << ((lcv>>2) - 11);\r
46\r
47 RateTableAdd[lcv] = ((7 - (lcv&3)) << 16) / denom;\r
48 RateTableSub[lcv] = ((-8 + (lcv&3)) << 16) / denom;\r
49\r
50 // XXX: this is wrong, we need more bits..\r
51 if (RateTableAdd[lcv] == 0)\r
52 RateTableAdd[lcv] = 1;\r
53 }\r
54}\r
55\r
56////////////////////////////////////////////////////////////////////////\r
57\r
58INLINE void StartADSR(int ch) // MIX ADSR\r
59{\r
60 spu.s_chan[ch].ADSRX.State = ADSR_ATTACK; // and init some adsr vars\r
61 spu.s_chan[ch].ADSRX.EnvelopeVol = 0;\r
62}\r
63\r
64////////////////////////////////////////////////////////////////////////\r
65\r
66static int MixADSR(ADSRInfoEx *adsr, int ns_to)\r
67{\r
68 int EnvelopeVol = adsr->EnvelopeVol;\r
69 int ns = 0, val, rto, level;\r
70\r
71 if (adsr->State == ADSR_RELEASE)\r
72 {\r
73 val = RateTableSub[adsr->ReleaseRate * 4];\r
74\r
75 if (adsr->ReleaseModeExp)\r
76 {\r
77 for (; ns < ns_to; ns++)\r
78 {\r
79 EnvelopeVol += ((long long)val * EnvelopeVol) >> (15+16);\r
80 if (EnvelopeVol <= 0)\r
81 break;\r
82\r
83 ChanBuf[ns] *= EnvelopeVol >> 21;\r
84 ChanBuf[ns] >>= 10;\r
85 }\r
86 }\r
87 else\r
88 {\r
89 for (; ns < ns_to; ns++)\r
90 {\r
91 EnvelopeVol += val;\r
92 if (EnvelopeVol <= 0)\r
93 break;\r
94\r
95 ChanBuf[ns] *= EnvelopeVol >> 21;\r
96 ChanBuf[ns] >>= 10;\r
97 }\r
98 }\r
99\r
100 goto done;\r
101 }\r
102\r
103 switch (adsr->State)\r
104 {\r
105 case ADSR_ATTACK: // -> attack\r
106 rto = 0;\r
107 if (adsr->AttackModeExp && EnvelopeVol >= 0x60000000)\r
108 rto = 8;\r
109 val = RateTableAdd[adsr->AttackRate + rto];\r
110\r
111 for (; ns < ns_to; ns++)\r
112 {\r
113 EnvelopeVol += val;\r
114 if (EnvelopeVol < 0)\r
115 break;\r
116\r
117 ChanBuf[ns] *= EnvelopeVol >> 21;\r
118 ChanBuf[ns] >>= 10;\r
119 }\r
120\r
121 if (EnvelopeVol < 0) // overflow\r
122 {\r
123 EnvelopeVol = 0x7fffffff;\r
124 adsr->State = ADSR_DECAY;\r
125 ns++; // sample is good already\r
126 goto decay;\r
127 }\r
128 break;\r
129\r
130 //--------------------------------------------------//\r
131 decay:\r
132 case ADSR_DECAY: // -> decay\r
133 val = RateTableSub[adsr->DecayRate * 4];\r
134 level = adsr->SustainLevel;\r
135\r
136 for (; ns < ns_to; )\r
137 {\r
138 EnvelopeVol += ((long long)val * EnvelopeVol) >> (15+16);\r
139 if (EnvelopeVol < 0)\r
140 EnvelopeVol = 0;\r
141\r
142 ChanBuf[ns] *= EnvelopeVol >> 21;\r
143 ChanBuf[ns] >>= 10;\r
144 ns++;\r
145\r
146 if (((EnvelopeVol >> 27) & 0xf) <= level)\r
147 {\r
148 adsr->State = ADSR_SUSTAIN;\r
149 goto sustain;\r
150 }\r
151 }\r
152 break;\r
153\r
154 //--------------------------------------------------//\r
155 sustain:\r
156 case ADSR_SUSTAIN: // -> sustain\r
157 if (adsr->SustainIncrease)\r
158 {\r
159 if (EnvelopeVol >= 0x7fff0000)\r
160 {\r
161 ns = ns_to;\r
162 break;\r
163 }\r
164\r
165 rto = 0;\r
166 if (adsr->SustainModeExp && EnvelopeVol >= 0x60000000)\r
167 rto = 8;\r
168 val = RateTableAdd[adsr->SustainRate + rto];\r
169\r
170 for (; ns < ns_to; ns++)\r
171 {\r
172 EnvelopeVol += val;\r
173 if ((unsigned int)EnvelopeVol >= 0x7fe00000)\r
174 {\r
175 EnvelopeVol = 0x7fffffff;\r
176 ns = ns_to;\r
177 break;\r
178 }\r
179\r
180 ChanBuf[ns] *= EnvelopeVol >> 21;\r
181 ChanBuf[ns] >>= 10;\r
182 }\r
183 }\r
184 else\r
185 {\r
186 val = RateTableSub[adsr->SustainRate];\r
187 if (adsr->SustainModeExp)\r
188 {\r
189 for (; ns < ns_to; ns++)\r
190 {\r
191 EnvelopeVol += ((long long)val * EnvelopeVol) >> (15+16);\r
192 if (EnvelopeVol < 0) \r
193 break;\r
194\r
195 ChanBuf[ns] *= EnvelopeVol >> 21;\r
196 ChanBuf[ns] >>= 10;\r
197 }\r
198 }\r
199 else\r
200 {\r
201 for (; ns < ns_to; ns++)\r
202 {\r
203 EnvelopeVol += val;\r
204 if (EnvelopeVol < 0) \r
205 break;\r
206\r
207 ChanBuf[ns] *= EnvelopeVol >> 21;\r
208 ChanBuf[ns] >>= 10;\r
209 }\r
210 }\r
211 }\r
212 break;\r
213 }\r
214\r
215done:\r
216 adsr->EnvelopeVol = EnvelopeVol;\r
217 return ns;\r
218}\r
219\r
220static int SkipADSR(ADSRInfoEx *adsr, int ns_to)\r
221{\r
222 int EnvelopeVol = adsr->EnvelopeVol;\r
223 int ns = 0, val, rto, level;\r
224 int64_t v64;\r
225\r
226 if (adsr->State == ADSR_RELEASE)\r
227 {\r
228 val = RateTableSub[adsr->ReleaseRate * 4];\r
229 if (adsr->ReleaseModeExp)\r
230 {\r
231 for (; ns < ns_to; ns++)\r
232 {\r
233 EnvelopeVol += ((long long)val * EnvelopeVol) >> (15+16);\r
234 if (EnvelopeVol <= 0)\r
235 break;\r
236 }\r
237 }\r
238 else\r
239 {\r
240 v64 = EnvelopeVol;\r
241 v64 += (int64_t)val * ns_to;\r
242 EnvelopeVol = (int)v64;\r
243 if (v64 > 0)\r
244 ns = ns_to;\r
245 }\r
246 goto done;\r
247 }\r
248\r
249 switch (adsr->State)\r
250 {\r
251 case ADSR_ATTACK: // -> attack\r
252 rto = 0;\r
253 if (adsr->AttackModeExp && EnvelopeVol >= 0x60000000)\r
254 rto = 8;\r
255 val = RateTableAdd[adsr->AttackRate + rto];\r
256\r
257 for (; ns < ns_to; ns++)\r
258 {\r
259 EnvelopeVol += val;\r
260 if (EnvelopeVol < 0)\r
261 break;\r
262 }\r
263 if (EnvelopeVol < 0) // overflow\r
264 {\r
265 EnvelopeVol = 0x7fffffff;\r
266 adsr->State = ADSR_DECAY;\r
267 ns++;\r
268 goto decay;\r
269 }\r
270 break;\r
271\r
272 //--------------------------------------------------//\r
273 decay:\r
274 case ADSR_DECAY: // -> decay\r
275 val = RateTableSub[adsr->DecayRate * 4];\r
276 level = adsr->SustainLevel;\r
277\r
278 for (; ns < ns_to; )\r
279 {\r
280 EnvelopeVol += ((long long)val * EnvelopeVol) >> (15+16);\r
281 if (EnvelopeVol < 0)\r
282 EnvelopeVol = 0;\r
283\r
284 ns++;\r
285\r
286 if (((EnvelopeVol >> 27) & 0xf) <= level)\r
287 {\r
288 adsr->State = ADSR_SUSTAIN;\r
289 goto sustain;\r
290 }\r
291 }\r
292 break;\r
293\r
294 //--------------------------------------------------//\r
295 sustain:\r
296 case ADSR_SUSTAIN: // -> sustain\r
297 if (adsr->SustainIncrease)\r
298 {\r
299 ns = ns_to;\r
300\r
301 if (EnvelopeVol >= 0x7fff0000)\r
302 break;\r
303\r
304 rto = 0;\r
305 if (adsr->SustainModeExp && EnvelopeVol >= 0x60000000)\r
306 rto = 8;\r
307 val = RateTableAdd[adsr->SustainRate + rto];\r
308\r
309 v64 = EnvelopeVol;\r
310 v64 += (int64_t)val * (ns_to - ns);\r
311 EnvelopeVol = (int)v64;\r
312 if (v64 >= 0x7fe00000ll)\r
313 EnvelopeVol = 0x7fffffff;\r
314 }\r
315 else\r
316 {\r
317 val = RateTableSub[adsr->SustainRate];\r
318 if (adsr->SustainModeExp)\r
319 {\r
320 for (; ns < ns_to; ns++)\r
321 {\r
322 EnvelopeVol += ((long long)val * EnvelopeVol) >> (15+16);\r
323 if (EnvelopeVol < 0)\r
324 break;\r
325 }\r
326 }\r
327 else\r
328 {\r
329 v64 = EnvelopeVol;\r
330 v64 += (int64_t)val * (ns_to - ns);\r
331 EnvelopeVol = (int)v64;\r
332 if (v64 > 0)\r
333 {\r
334 ns = ns_to;\r
335 break;\r
336 }\r
337 }\r
338 }\r
339 break;\r
340 }\r
341\r
342done:\r
343 adsr->EnvelopeVol = EnvelopeVol;\r
344 return ns;\r
345}\r
346\r
347#endif\r
348\r
349/*\r
350James Higgs ADSR investigations:\r
351\r
352PSX SPU Envelope Timings\r
353~~~~~~~~~~~~~~~~~~~~~~~~\r
354\r
355First, here is an extract from doomed's SPU doc, which explains the basics\r
356of the SPU "volume envelope": \r
357\r
358*** doomed doc extract start ***\r
359\r
360--------------------------------------------------------------------------\r
361Voices.\r
362--------------------------------------------------------------------------\r
363The SPU has 24 hardware voices. These voices can be used to reproduce sample\r
364data, noise or can be used as frequency modulator on the next voice.\r
365Each voice has it's own programmable ADSR envelope filter. The main volume\r
366can be programmed independently for left and right output.\r
367\r
368The ADSR envelope filter works as follows:\r
369Ar = Attack rate, which specifies the speed at which the volume increases\r
370 from zero to it's maximum value, as soon as the note on is given. The\r
371 slope can be set to lineair or exponential.\r
372Dr = Decay rate specifies the speed at which the volume decreases to the\r
373 sustain level. Decay is always decreasing exponentially.\r
374Sl = Sustain level, base level from which sustain starts.\r
375Sr = Sustain rate is the rate at which the volume of the sustained note\r
376 increases or decreases. This can be either lineair or exponential.\r
377Rr = Release rate is the rate at which the volume of the note decreases\r
378 as soon as the note off is given.\r
379\r
380 lvl |\r
381 ^ | /\Dr __\r
382 Sl _| _ / _ \__--- \\r
383 | / ---__ \ Rr\r
384 | /Ar Sr \ \\r
385 | / \\\r
386 |/___________________\________\r
387 ->time\r
388\r
389The overal volume can also be set to sweep up or down lineairly or\r
390exponentially from it's current value. This can be done seperately\r
391for left and right.\r
392\r
393Relevant SPU registers:\r
394-------------------------------------------------------------\r
395$1f801xx8 Attack/Decay/Sustain level\r
396bit |0f|0e 0d 0c 0b 0a 09 08|07 06 05 04|03 02 01 00|\r
397desc.|Am| Ar |Dr |Sl |\r
398\r
399Am 0 Attack mode Linear\r
400 1 Exponential\r
401\r
402Ar 0-7f attack rate\r
403Dr 0-f decay rate\r
404Sl 0-f sustain level\r
405-------------------------------------------------------------\r
406$1f801xxa Sustain rate, Release Rate.\r
407bit |0f|0e|0d|0c 0b 0a 09 08 07 06|05|04 03 02 01 00|\r
408desc.|Sm|Sd| 0| Sr |Rm|Rr |\r
409\r
410Sm 0 sustain rate mode linear\r
411 1 exponential\r
412Sd 0 sustain rate mode increase\r
413 1 decrease\r
414Sr 0-7f Sustain Rate\r
415Rm 0 Linear decrease\r
416 1 Exponential decrease\r
417Rr 0-1f Release Rate\r
418\r
419Note: decay mode is always Expontial decrease, and thus cannot\r
420be set.\r
421-------------------------------------------------------------\r
422$1f801xxc Current ADSR volume\r
423bit |0f 0e 0d 0c 0b 0a 09 08 07 06 05 04 03 02 01 00|\r
424desc.|ADSRvol |\r
425\r
426ADSRvol Returns the current envelope volume when\r
427 read.\r
428-- James' Note: return range: 0 -> 32767\r
429\r
430*** doomed doc extract end *** \r
431\r
432By using a small PSX proggie to visualise the envelope as it was played,\r
433the following results for envelope timing were obtained:\r
434\r
4351. Attack rate value (linear mode)\r
436\r
437 Attack value range: 0 -> 127\r
438\r
439 Value | 48 | 52 | 56 | 60 | 64 | 68 | 72 | | 80 |\r
440 -----------------------------------------------------------------\r
441 Frames | 11 | 21 | 42 | 84 | 169| 338| 676| |2890|\r
442\r
443 Note: frames is no. of PAL frames to reach full volume (100%\r
444 amplitude)\r
445\r
446 Hmm, noticing that the time taken to reach full volume doubles\r
447 every time we add 4 to our attack value, we know the equation is\r
448 of form:\r
449 frames = k * 2 ^ (value / 4)\r
450\r
451 (You may ponder about envelope generator hardware at this point,\r
452 or maybe not... :)\r
453\r
454 By substituting some stuff and running some checks, we get:\r
455\r
456 k = 0.00257 (close enuf)\r
457\r
458 therefore,\r
459 frames = 0.00257 * 2 ^ (value / 4)\r
460 If you just happen to be writing an emulator, then you can probably\r
461 use an equation like:\r
462\r
463 %volume_increase_per_tick = 1 / frames\r
464\r
465\r
466 ------------------------------------\r
467 Pete:\r
468 ms=((1<<(value>>2))*514)/10000\r
469 ------------------------------------\r
470\r
4712. Decay rate value (only has log mode)\r
472\r
473 Decay value range: 0 -> 15\r
474\r
475 Value | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |\r
476 ------------------------------------------------\r
477 frames | | | | | 6 | 12 | 24 | 47 |\r
478\r
479 Note: frames here is no. of PAL frames to decay to 50% volume.\r
480\r
481 formula: frames = k * 2 ^ (value)\r
482\r
483 Substituting, we get: k = 0.00146\r
484\r
485 Further info on logarithmic nature:\r
486 frames to decay to sustain level 3 = 3 * frames to decay to \r
487 sustain level 9\r
488\r
489 Also no. of frames to 25% volume = roughly 1.85 * no. of frames to\r
490 50% volume.\r
491\r
492 Frag it - just use linear approx.\r
493\r
494 ------------------------------------\r
495 Pete:\r
496 ms=((1<<value)*292)/10000\r
497 ------------------------------------\r
498\r
499\r
5003. Sustain rate value (linear mode)\r
501\r
502 Sustain rate range: 0 -> 127\r
503\r
504 Value | 48 | 52 | 56 | 60 | 64 | 68 | 72 |\r
505 -------------------------------------------\r
506 frames | 9 | 19 | 37 | 74 | 147| 293| 587|\r
507\r
508 Here, frames = no. of PAL frames for volume amplitude to go from 100%\r
509 to 0% (or vice-versa).\r
510\r
511 Same formula as for attack value, just a different value for k:\r
512\r
513 k = 0.00225\r
514\r
515 ie: frames = 0.00225 * 2 ^ (value / 4)\r
516\r
517 For emulation purposes:\r
518\r
519 %volume_increase_or_decrease_per_tick = 1 / frames\r
520\r
521 ------------------------------------\r
522 Pete:\r
523 ms=((1<<(value>>2))*450)/10000\r
524 ------------------------------------\r
525\r
526\r
5274. Release rate (linear mode)\r
528\r
529 Release rate range: 0 -> 31\r
530\r
531 Value | 13 | 14 | 15 | 16 | 17 |\r
532 ---------------------------------------------------------------\r
533 frames | 18 | 36 | 73 | 146| 292|\r
534\r
535 Here, frames = no. of PAL frames to decay from 100% vol to 0% vol\r
536 after "note-off" is triggered.\r
537\r
538 Formula: frames = k * 2 ^ (value)\r
539\r
540 And so: k = 0.00223\r
541\r
542 ------------------------------------\r
543 Pete:\r
544 ms=((1<<value)*446)/10000\r
545 ------------------------------------\r
546\r
547\r
548Other notes: \r
549\r
550Log stuff not figured out. You may get some clues from the "Decay rate"\r
551stuff above. For emu purposes it may not be important - use linear\r
552approx.\r
553\r
554To get timings in millisecs, multiply frames by 20.\r
555\r
556\r
557\r
558- James Higgs 17/6/2000\r
559james7780@yahoo.com\r
560\r
561//---------------------------------------------------------------\r
562\r
563OLD adsr mixing according to james' rules... has to be called\r
564every one millisecond\r
565\r
566\r
567 long v,v2,lT,l1,l2,l3;\r
568\r
569 if(s_chan[ch].bStop) // psx wants to stop? -> release phase\r
570 {\r
571 if(s_chan[ch].ADSR.ReleaseVal!=0) // -> release not 0: do release (if 0: stop right now)\r
572 {\r
573 if(!s_chan[ch].ADSR.ReleaseVol) // --> release just started? set up the release stuff\r
574 {\r
575 s_chan[ch].ADSR.ReleaseStartTime=s_chan[ch].ADSR.lTime;\r
576 s_chan[ch].ADSR.ReleaseVol=s_chan[ch].ADSR.lVolume;\r
577 s_chan[ch].ADSR.ReleaseTime = // --> calc how long does it take to reach the wanted sus level\r
578 (s_chan[ch].ADSR.ReleaseTime*\r
579 s_chan[ch].ADSR.ReleaseVol)/1024;\r
580 }\r
581 // -> NO release exp mode used (yet)\r
582 v=s_chan[ch].ADSR.ReleaseVol; // -> get last volume\r
583 lT=s_chan[ch].ADSR.lTime- // -> how much time is past?\r
584 s_chan[ch].ADSR.ReleaseStartTime;\r
585 l1=s_chan[ch].ADSR.ReleaseTime;\r
586 \r
587 if(lT<l1) // -> we still have to release\r
588 {\r
589 v=v-((v*lT)/l1); // --> calc new volume\r
590 }\r
591 else // -> release is over: now really stop that sample\r
592 {v=0;s_chan[ch].bOn=0;s_chan[ch].ADSR.ReleaseVol=0;s_chan[ch].bNoise=0;}\r
593 }\r
594 else // -> release IS 0: release at once\r
595 {\r
596 v=0;s_chan[ch].bOn=0;s_chan[ch].ADSR.ReleaseVol=0;s_chan[ch].bNoise=0;\r
597 }\r
598 }\r
599 else \r
600 {//--------------------------------------------------// not in release phase:\r
601 v=1024;\r
602 lT=s_chan[ch].ADSR.lTime;\r
603 l1=s_chan[ch].ADSR.AttackTime;\r
604 \r
605 if(lT<l1) // attack\r
606 { // no exp mode used (yet)\r
607// if(s_chan[ch].ADSR.AttackModeExp)\r
608// {\r
609// v=(v*lT)/l1;\r
610// }\r
611// else\r
612 {\r
613 v=(v*lT)/l1;\r
614 }\r
615 if(v==0) v=1;\r
616 }\r
617 else // decay\r
618 { // should be exp, but who cares? ;)\r
619 l2=s_chan[ch].ADSR.DecayTime;\r
620 v2=s_chan[ch].ADSR.SustainLevel;\r
621\r
622 lT-=l1;\r
623 if(lT<l2)\r
624 {\r
625 v-=(((v-v2)*lT)/l2);\r
626 }\r
627 else // sustain\r
628 { // no exp mode used (yet)\r
629 l3=s_chan[ch].ADSR.SustainTime;\r
630 lT-=l2;\r
631 if(s_chan[ch].ADSR.SustainModeDec>0)\r
632 {\r
633 if(l3!=0) v2+=((v-v2)*lT)/l3;\r
634 else v2=v;\r
635 }\r
636 else\r
637 {\r
638 if(l3!=0) v2-=(v2*lT)/l3;\r
639 else v2=v;\r
640 }\r
641\r
642 if(v2>v) v2=v;\r
643 if(v2<=0) {v2=0;s_chan[ch].bOn=0;s_chan[ch].ADSR.ReleaseVol=0;s_chan[ch].bNoise=0;}\r
644\r
645 v=v2;\r
646 }\r
647 }\r
648 }\r
649\r
650 //----------------------------------------------------// \r
651 // ok, done for this channel, so increase time\r
652\r
653 s_chan[ch].ADSR.lTime+=1; // 1 = 1.020408f ms; \r
654\r
655 if(v>1024) v=1024; // adjust volume\r
656 if(v<0) v=0; \r
657 s_chan[ch].ADSR.lVolume=v; // store act volume\r
658\r
659 return v; // return the volume factor\r
660*/\r
661\r
662\r
663//-----------------------------------------------------------------------------\r
664//-----------------------------------------------------------------------------\r
665//-----------------------------------------------------------------------------\r
666\r
667\r
668/*\r
669-----------------------------------------------------------------------------\r
670Neill Corlett\r
671Playstation SPU envelope timing notes\r
672-----------------------------------------------------------------------------\r
673\r
674This is preliminary. This may be wrong. But the model described herein fits\r
675all of my experimental data, and it's just simple enough to sound right.\r
676\r
677ADSR envelope level ranges from 0x00000000 to 0x7FFFFFFF internally.\r
678The value returned by channel reg 0xC is (envelope_level>>16).\r
679\r
680Each sample, an increment or decrement value will be added to or\r
681subtracted from this envelope level.\r
682\r
683Create the rate log table. The values double every 4 entries.\r
684 entry #0 = 4\r
685\r
686 4, 5, 6, 7,\r
687 8,10,12,14,\r
688 16,20,24,28, ...\r
689\r
690 entry #40 = 4096...\r
691 entry #44 = 8192...\r
692 entry #48 = 16384...\r
693 entry #52 = 32768...\r
694 entry #56 = 65536...\r
695\r
696increments and decrements are in terms of ratelogtable[n]\r
697n may exceed the table bounds (plan on n being between -32 and 127).\r
698table values are all clipped between 0x00000000 and 0x3FFFFFFF\r
699\r
700when you "voice on", the envelope is always fully reset.\r
701(yes, it may click. the real thing does this too.)\r
702\r
703envelope level begins at zero.\r
704\r
705each state happens for at least 1 cycle\r
706(transitions are not instantaneous)\r
707this may result in some oddness: if the decay rate is uberfast, it will cut\r
708the envelope from full down to half in one sample, potentially skipping over\r
709the sustain level\r
710\r
711ATTACK\r
712------\r
713- if the envelope level has overflowed past the max, clip to 0x7FFFFFFF and\r
714 proceed to DECAY.\r
715\r
716Linear attack mode:\r
717- line extends upward to 0x7FFFFFFF\r
718- increment per sample is ratelogtable[(Ar^0x7F)-0x10]\r
719\r
720Logarithmic attack mode:\r
721if envelope_level < 0x60000000:\r
722 - line extends upward to 0x60000000\r
723 - increment per sample is ratelogtable[(Ar^0x7F)-0x10]\r
724else:\r
725 - line extends upward to 0x7FFFFFFF\r
726 - increment per sample is ratelogtable[(Ar^0x7F)-0x18]\r
727\r
728DECAY\r
729-----\r
730- if ((envelope_level>>27)&0xF) <= Sl, proceed to SUSTAIN.\r
731 Do not clip to the sustain level.\r
732- current line ends at (envelope_level & 0x07FFFFFF)\r
733- decrement per sample depends on (envelope_level>>28)&0x7\r
734 0: ratelogtable[(4*(Dr^0x1F))-0x18+0]\r
735 1: ratelogtable[(4*(Dr^0x1F))-0x18+4]\r
736 2: ratelogtable[(4*(Dr^0x1F))-0x18+6]\r
737 3: ratelogtable[(4*(Dr^0x1F))-0x18+8]\r
738 4: ratelogtable[(4*(Dr^0x1F))-0x18+9]\r
739 5: ratelogtable[(4*(Dr^0x1F))-0x18+10]\r
740 6: ratelogtable[(4*(Dr^0x1F))-0x18+11]\r
741 7: ratelogtable[(4*(Dr^0x1F))-0x18+12]\r
742 (note that this is the same as the release rate formula, except that\r
743 decay rates 10-1F aren't possible... those would be slower in theory)\r
744\r
745SUSTAIN\r
746-------\r
747- no terminating condition except for voice off\r
748- Sd=0 (increase) behavior is identical to ATTACK for both log and linear.\r
749- Sd=1 (decrease) behavior:\r
750Linear sustain decrease:\r
751- line extends to 0x00000000\r
752- decrement per sample is ratelogtable[(Sr^0x7F)-0x0F]\r
753Logarithmic sustain decrease:\r
754- current line ends at (envelope_level & 0x07FFFFFF)\r
755- decrement per sample depends on (envelope_level>>28)&0x7\r
756 0: ratelogtable[(Sr^0x7F)-0x1B+0]\r
757 1: ratelogtable[(Sr^0x7F)-0x1B+4]\r
758 2: ratelogtable[(Sr^0x7F)-0x1B+6]\r
759 3: ratelogtable[(Sr^0x7F)-0x1B+8]\r
760 4: ratelogtable[(Sr^0x7F)-0x1B+9]\r
761 5: ratelogtable[(Sr^0x7F)-0x1B+10]\r
762 6: ratelogtable[(Sr^0x7F)-0x1B+11]\r
763 7: ratelogtable[(Sr^0x7F)-0x1B+12]\r
764\r
765RELEASE\r
766-------\r
767- if the envelope level has overflowed to negative, clip to 0 and QUIT.\r
768\r
769Linear release mode:\r
770- line extends to 0x00000000\r
771- decrement per sample is ratelogtable[(4*(Rr^0x1F))-0x0C]\r
772\r
773Logarithmic release mode:\r
774- line extends to (envelope_level & 0x0FFFFFFF)\r
775- decrement per sample depends on (envelope_level>>28)&0x7\r
776 0: ratelogtable[(4*(Rr^0x1F))-0x18+0]\r
777 1: ratelogtable[(4*(Rr^0x1F))-0x18+4]\r
778 2: ratelogtable[(4*(Rr^0x1F))-0x18+6]\r
779 3: ratelogtable[(4*(Rr^0x1F))-0x18+8]\r
780 4: ratelogtable[(4*(Rr^0x1F))-0x18+9]\r
781 5: ratelogtable[(4*(Rr^0x1F))-0x18+10]\r
782 6: ratelogtable[(4*(Rr^0x1F))-0x18+11]\r
783 7: ratelogtable[(4*(Rr^0x1F))-0x18+12]\r
784\r
785-----------------------------------------------------------------------------\r
786*/\r
787\r
788// vim:shiftwidth=1:expandtab\r
ARM optimized PCSX fork