Merge branch 'OOP'
[Faustine.git] / interpretor / faust-0.9.47mr3 / compiler / signals / sigraterules.cpp
1 /************************************************************************
2 ************************************************************************
3 FAUST compiler
4 Copyright (C) 2003-2004 GRAME, Centre National de Creation Musicale
5 ---------------------------------------------------------------------
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 ************************************************************************
20 ************************************************************************/
21
22
23
24 #include <stdio.h>
25 #include <assert.h>
26 #include <fstream>
27 #include <time.h>
28
29
30 #include "sigtype.hh"
31 #include "sigprint.hh"
32 #include "ppsig.hh"
33 //#include "prim.hh"
34 #include "prim2.hh"
35 #include "xtended.hh"
36 #include "recursivness.hh"
37
38 #include "sigtyperules.hh"
39 #include "sigraterules.hh"
40
41
42
43 //--------------------------------------------------------------------------
44 // Uncomment to activate type inference tracing
45
46 //#define TRACE(x) x
47 #define TRACE(x) 0;
48
49
50
51
52
53 /**
54
55 ========================================== RATE INFERENCE =========================================
56 [Public functions]
57
58
59 */
60
61 /**************************************************************************************************
62
63 Internal prototypes
64
65 **************************************************************************************************/
66
67 static Tree inferreMultiRates(Tree lsig1, bool& success);
68 static ostream& printRateEnvironment(ostream& fout, Tree E);
69 static ostream& printRateEnvironmentList(ostream& fout, Tree LE);
70 static void doInferreRate(Tree sig, int* rate, Tree& renv);
71 static void inferreRate(Tree sig, int* rate, Tree& E);
72 static Tree addToMultiRates(Tree E1, Tree LE, bool& success);
73 static Tree addRecursiveSignals(Tree lsig);
74 static Tree doAddRecursiveSignals(Tree sig, Tree accSig);
75 static Tree flatRateEnvironmentList(Tree lre);
76
77 static int computeRate(Tree sig, Tree renv, property<int>& rateProperty);
78
79
80
81 /**************************************************************************************************
82 **************************************************************************************************
83 **************************************************************************************************
84
85 Public Functions
86
87 **************************************************************************************************
88 **************************************************************************************************
89 **************************************************************************************************/
90
91 /**
92 * Inferre the rate of a list of signals.
93 */
94 Tree inferreMultiRates(Tree lsig1, bool& success)
95 {
96 vector<Tree> sigs;
97 vector<Tree> envs;
98 vector<int> rates;
99
100 Tree lsig2 = addRecursiveSignals(lsig1);
101 TRACE(cerr << "lsig2 = " << *lsig2 << endl);
102
103 while (isList(lsig2)) {
104 Tree s = hd(lsig2); lsig2 = tl(lsig2);
105 Tree E; int r; inferreRate(s, &r, E);
106 if (r==0) {
107 success = false;
108 cerr << "ERROR inferreMultiRates failed 1" << endl;
109 return nil;
110 }
111 sigs.push_back(s);
112 envs.push_back(E);
113 rates.push_back(r);
114 }
115
116 // combines all the rate environements
117 Tree LE = nil;
118 success = true;
119 for (unsigned int i=0; success && i<envs.size(); i++) {
120 LE = addToMultiRates(envs[i], LE, success);
121 }
122 TRACE(cerr << "***multirates :"; printRateEnvironmentList(cerr, LE); cerr << endl);
123 Tree RE = flatRateEnvironmentList(LE);
124 TRACE(cerr << "***flat rate :"; printRateEnvironment(cerr, RE); cerr << endl);
125
126 return RE;
127 }
128
129
130 /**
131 * Print a rate environment
132 */
133 ostream& printRateEnvironment(ostream& fout, Tree E)
134 {
135 string sep = "";
136 fout << "rates {";
137 while (isList(E)) {
138 fout << sep << ppsig(hd(hd(E))) << ":" << tree2int(tl(hd(E)));
139 sep=",";
140 E = tl(E);
141 }
142 fout << "}";
143 return fout;
144 }
145
146
147 /**
148 * Print a list of rate environments
149 */
150 ostream& printRateEnvironmentList(ostream& fout, Tree LE)
151 {
152 string sep = "";
153 fout << "multi{";
154 while (isList(LE)) {
155 fout << sep; printRateEnvironment(fout, hd(LE));
156 sep="++";
157 LE = tl(LE);
158 }
159 fout << "}";
160 return fout;
161 }
162
163
164
165 /**************************************************************************************************
166 **************************************************************************************************
167 **************************************************************************************************
168
169 IMPLEMENTATION
170
171 **************************************************************************************************
172 **************************************************************************************************
173 **************************************************************************************************/
174
175
176 /**
177 * Greatest common divisor
178 */
179 static int TRACED_gcd(int a, int b);
180
181 static int gcd(int a, int b)
182 {
183 int r = TRACED_gcd(a,b);
184 //cerr << TABBER << "gcd(" << a << ',' << b <<") = " << r << endl;
185 return r;
186 }
187
188
189 static int TRACED_gcd(int a, int b)
190 {
191 return (b==0) ? a : gcd (b, a%b);
192 }
193
194 /**
195 * Least common multiple
196 */
197 static int lcm(int a, int b)
198 {
199 int r = (a*b)/gcd(a,b);
200 //cerr << TABBER << "lcm(" << a << ',' << b <<") = " << r << endl;
201 return r;
202 }
203
204
205 /**
206 * Add to a list of existing signals lsig the list of recursive signals apprearing in lsig
207 */
208
209 static Tree addRecursiveSignals(Tree lsig)
210 {
211 CTree::startNewVisit();
212
213 Tree lsig2 = lsig;
214 while (isList(lsig)) {
215 lsig2 = doAddRecursiveSignals(hd(lsig), lsig2);
216 lsig = tl(lsig);
217 }
218 return lsig2;
219 }
220
221
222 static Tree doAddRecursiveSignals(Tree sig, Tree accSig)
223 {
224 TRACE(cerr << ++TABBER << "doAddRecursiveSignals(" << *sig << ',' << *accSig << ')' << endl);
225 if ( ! sig->isAlreadyVisited() ) {
226 int i;
227 Tree rsig, id, body;
228 sig->setVisited();
229 if (isProj(sig,&i,rsig) && isRec(rsig, id, body)) {
230 Tree p = nth(body,i);
231 accSig = doAddRecursiveSignals(p, cons(p,accSig));
232 } else {
233 assert(!isProj(sig,&i,rsig));
234
235 vector<Tree> subsigs;
236 getSubSignals(sig,subsigs,false);
237 for (unsigned int i=0; i<subsigs.size(); i++) {
238 accSig = doAddRecursiveSignals(subsigs[i], accSig);
239 }
240 }
241 }
242 TRACE(cerr << --TABBER << "doAddRecursiveSignals(" << *sig << ',' << *accSig << ") -> " << *accSig << endl);
243 return accSig;
244 }
245
246 /** *********************************** RATE ENVIRONMENTS ************************************************
247
248 A rate environement E = {(s1,r1), (s2,r2), ...} is a set of pairs associating a signal and a rate. The
249 signals are unique : if (s1,r1) and (s2,r2) are in E then s1=s2 => r1=r2.
250
251 The environment is kept ordered
252
253
254 **********************************************************************************************************/
255
256
257
258
259 /**
260 * Add a pair signal s1 x rate r1 to rate environment E
261 */
262 static Tree addRateEnv(Tree s1, int r1, Tree E)
263 {
264 if (isList(E)) {
265 Tree s2 = hd(hd(E));
266 if (s1 < s2) {
267 return cons(cons(s1,tree(r1)),E);
268 } else if (s1 == s2) {
269 return cons(cons(s1,tree(r1)),tl(E));
270 } else {
271 return cons(hd(E), addRateEnv(s1,r1,tl(E)));
272 }
273 } else {
274 return cons(cons(s1,tree(r1)),nil);
275 }
276 }
277
278
279 /**
280 * multiply by n all the rates of rate environment E
281 * E={(s1,r1),...} -> E'={(s1,n.r1),...}
282 */
283 static Tree TRACED_multRateEnv(int n, Tree E);
284
285 static Tree multRateEnv(int n, Tree E)
286 {
287 TRACE(cerr << ++TABBER << "multRateEnv(" << n << ", " << *E << ")" << endl);
288 Tree result = TRACED_multRateEnv(n, E);
289 TRACE(cerr << --TABBER << "multRateEnv(" << n << ", " << *E << ") -> " << *result << endl);
290 return result;
291
292 }
293
294
295 static Tree TRACED_multRateEnv(int n, Tree E)
296 {
297 if (isList(E)) {
298 Tree p = hd(E);
299 Tree k = hd(p);
300 int r = tree2int(tl(p));
301 Tree q = cons(k, tree(r*n));
302 return cons(q, multRateEnv(n, tl(E)));
303 } else {
304 return nil;
305 }
306 }
307
308
309 /**
310 * Get value associated to key k in "function" l
311 * returns true if a value was found.
312 */
313
314 static bool getRateEnv(Tree k, int* i, Tree l)
315 {
316 if (isNil(l)) {
317 return false;
318 } else {
319 assert (isList(l));
320 Tree r = hd(hd(l));
321 if (k < r) {
322 return false; // not found
323 } else if (k == r) {
324 *i = tree2int(tl(hd(l)));
325 return true;
326 } else {
327 return getRateEnv(k,i,tl(l));
328 }
329 }
330 }
331
332
333
334 /**
335 * two rate environments are compatible if common rates
336 * are linked by the same ratio
337 */
338
339 static bool checkRatesCompatible(Tree R1, Tree R2, int n1, int n2)
340 {
341 if (isNil(R1) || isNil(R2)) {
342 return true;
343 } else {
344 Tree p1 = hd (R1);
345 Tree p2 = hd (R2);
346
347 Tree k1 = hd (p1);
348 Tree k2 = hd (p2);
349
350 if (k1 < k2) {
351 return checkRatesCompatible(tl(R1), R2, n1, n2);
352 } else if (k1 > k2) {
353 return checkRatesCompatible(R1, tl(R2), n1, n2);
354 } else {
355 Tree v1 = tl (p1);
356 Tree v2 = tl (p2);
357
358 if (tree2int(v1)*n1 == tree2int(v2)*n2) {
359 return checkRatesCompatible(tl(R1), tl(R2), n1, n2);
360 } else {
361 return false;
362 }
363 }
364 }
365 }
366
367
368
369 /**
370 * Two rate environments are independent if they don't have any
371 * signals in common
372 */
373
374 static bool areRatesIndependent(Tree R1, Tree R2)
375 {
376 if (isNil(R1) || isNil(R2)) {
377 return true;
378 } else {
379 Tree p1 = hd (R1);
380 Tree p2 = hd (R2);
381
382 Tree s1 = hd (p1);
383 Tree s2 = hd (p2);
384
385 if (s1 < s2) {
386 return areRatesIndependent(tl(R1), R2);
387 } else if (s2 < s1) {
388 return areRatesIndependent(R1, tl(R2));
389 } else {
390 return false; // s1 and s2 are in common
391 }
392 }
393 }
394
395
396
397
398 /**
399 * Two rate environments are compatible if common rates
400 * are linked by the same ratio
401 */
402
403 static bool areRatesCompatible(Tree R1, Tree R2, int& n1, int& n2)
404 {
405 if (isNil(R1) || isNil(R2)) {
406
407 n1 = 1; n2 = 1;
408 return true;
409
410 } else {
411
412 Tree p1 = hd (R1);
413 Tree p2 = hd (R2);
414
415 Tree k1 = hd (p1);
416 Tree k2 = hd (p2);
417
418 if (k1 < k2) {
419
420 return areRatesCompatible(tl(R1), R2, n1, n2);
421
422 } else if (k1 > k2) {
423
424 return areRatesCompatible(R1, tl(R2), n1, n2);
425
426 } else {
427
428 // we have a common expression
429 Tree v1 = tl (p1);
430 Tree v2 = tl (p2);
431
432 int r1 = tree2int(v1);
433 int r2 = tree2int(v2);
434
435 int m = lcm(r1, r2);
436
437 // we update the n1 and n2 coefficients
438 n1 = m/r1;
439 n2 = m/r2;
440
441 // and we check that the rest of the environments are compatible
442 return checkRatesCompatible(tl(R1), tl(R2), n1, n2);
443 }
444 }
445 }
446
447
448 /**
449 * Merge two compatible rate environments. Rate environments are
450 * compatible if common expressions have same rate.
451 * Returns the merge environment and success flag
452 */
453 static Tree TRACED_mergeRateEnvironment(Tree R1, Tree R2, bool& success);
454
455 static Tree mergeRateEnvironment(Tree R1, Tree R2, bool& success)
456 {
457 TRACE(cerr << ++TABBER << "mergeRateEnvironment(" << *R1 << ", " << *R2 << ")" << endl);
458 Tree result = TRACED_mergeRateEnvironment(R1, R2, success);
459 if (success) {
460 TRACE(cerr << --TABBER << "mergeRateEnvironment(" << *R1 << ", " << *R2 << ") -> " << *result << endl);
461 } else {
462 TRACE(cerr << --TABBER << "mergeRateEnvironment(" << *R1 << ", " << *R2 << ") -> FAILED" << endl);
463 }
464 return result;
465 }
466
467
468
469
470 static Tree TRACED_mergeRateEnvironment(Tree R1, Tree R2, bool& success)
471 {
472 if (isNil(R1)) {
473
474 success = true;
475 return R2;
476
477 } else if (isNil(R2)) {
478
479 success = true;
480 return R1;
481
482 } else {
483
484 Tree p1 = hd (R1);
485 Tree p2 = hd (R2);
486
487 Tree k1 = hd (p1);
488 Tree k2 = hd (p2);
489
490 if (k1 < k2) {
491
492 return cons(p1, mergeRateEnvironment(tl(R1), R2, success));
493
494 } else if (k2 < k1) {
495
496 return cons(p2, mergeRateEnvironment(R1, tl(R2), success));
497
498 } else {
499
500 // we have a common expression
501 Tree r1 = tl (p1);
502 Tree r2 = tl (p2);
503
504 if (r1 == r2) {
505 // fine, same rate
506 return cons(p2, mergeRateEnvironment(tl(R1), tl(R2), success));
507 } else {
508 success = false;
509 return nil;
510 }
511 }
512 }
513 }
514
515 /**
516 * Merge a list of independent rate environments into a single rate environment
517 */
518 static Tree flatRateEnvironmentList(Tree lre)
519 {
520 Tree e = nil;
521 bool success = true;
522 while (isList(lre)) {
523 e = mergeRateEnvironment(hd(lre),e, success);
524 assert(success); // can't failed if environments are independant
525 lre = tl(lre);
526 }
527 return e;
528 }
529
530 /**
531
532 ========================================== RATE INFERENCE =========================================
533
534
535 */
536
537
538 property<Tree> gInferreRateProperty;
539
540 static void setInferreRateProperty(Tree sig, int rate, Tree renv)
541 {
542 gInferreRateProperty.set(sig, cons(tree(rate),renv));
543 }
544
545 static bool getInferreRateProperty(Tree sig, int* rate, Tree& renv)
546 {
547 Tree p;
548 if (gInferreRateProperty.get(sig, p)) {
549 *rate = tree2int(hd(p));
550 renv = tl(p);
551 return true;
552 } else {
553 return false;
554 }
555 }
556
557
558 /**
559 * Inferre rate (and rate environment) of a single signal.
560 * Use a property to cache previous results
561 */
562 static void inferreRate(Tree sig, int* rate, Tree& E)
563 {
564 TRACE(cerr << ++TABBER << "inferreRate(" << ppsig(sig) << ")" << endl);
565 if (! getInferreRateProperty(sig, rate, E)) {
566 doInferreRate(sig, rate, E);
567 setInferreRateProperty(sig, *rate, E);
568 }
569 TRACE(cerr << --TABBER << "inferreRate(" << ppsig(sig) << ") = " << *rate << " with " << *E << endl);
570 }
571
572
573 /**
574 * Checks that w denotes a positive constant integer signal n
575 * returns n or exit
576 */
577 static int checkSignalDenotesSize(Tree w, Tree sig)
578 {
579 // checks that w denotes a positive constant integer signal n
580 SimpleType* st = isSimpleType(getCertifiedSigType(w));
581
582 if (st && st->nature()==kInt) {
583 interval i = st->getInterval();
584 if (i.valid && i.lo >= 0 && i.lo == i.hi) {
585 return int(i.lo);
586 }
587 }
588 cerr << "ERROR in expression : " << ppsig(sig) << endl;
589 cerr << *w << " is not a positive constant integer" << endl;
590 exit(1);
591 }
592
593 /**
594 * Inferre the rate (and the rate environment) of a signal.
595 * A zero rate indicates an impossibility
596 */
597 static void doInferreRate(Tree sig, int* rate, Tree& E)
598 {
599 Tree w, x, rsig, id, body;
600 int i, in;
601
602 if ( isSigVectorize(sig, w, x) ) {
603
604 // -- rate(vectorize(n,x)) = rate(x)/n
605
606 VectorType* vt = isVectorType(getCertifiedSigType(sig)); assert(vt);
607 int n = vt->size(); assert(n>0);
608
609 int r; inferreRate(x, &r, E);
610 if ((r%n) == 0) {
611 // fine, the rate of x can be divided by n
612 // (note: this is compatible with r==0 indicating that x has no rate)
613 *rate = r/n;
614 } else {
615 // we need to scale the rates involved in x
616 int m = lcm(n,r);
617 *rate = m/n;
618 E = multRateEnv(m/r, E);
619 }
620
621 } else if ( isSigDownSample(sig, w, x) ) {
622
623 // -- rate(down(n,x) = rate(x)/n
624
625 int n = checkSignalDenotesSize(w, sig);
626
627 int r; inferreRate(x, &r, E);
628
629 if ((r%n) == 0) {
630 // fine, the rate of x can be divided by n
631 // (note: this is compatible with r==0 indicating that x has no rate)
632 *rate = r/n;
633 } else {
634 // we need to scale the rates involved in x
635 int m = lcm(n,r);
636 *rate = m/n;
637 E = multRateEnv(m/r, E);
638 }
639
640 } else if ( isSigUpSample(sig, w, x) ) {
641
642 // -- rate(up(n,x) = rate(x)*n
643
644 int n = checkSignalDenotesSize(w, sig);
645 int r; inferreRate(x, &r, E);
646 *rate = r*n;
647
648 } else if ( isSigSerialize(sig, x)) {
649
650 // -- rate(serialize(x) = rate(x)*n [with Type(x) = vector(n,T)]
651
652 VectorType* vt = isVectorType(getCertifiedSigType(x)); assert(vt);
653
654 int r; inferreRate(x, &r, E);
655 *rate = vt->size() * r;
656
657 } else if ( isSigInput(sig, &in)) {
658
659 // -- rate(input(x)) = 1
660
661 *rate = 1;
662 E = addRateEnv(sig,1,nil);
663
664 } else if (isProj(sig,&i,rsig) && isRec(rsig, id, body)) {
665
666 // -- rate(proj(i, x=(E0,E1,...))) = 1
667
668 *rate = 1;
669 E = addRateEnv(sig,1,nil);
670
671 } else {
672
673 // -- rate(op()) = 1
674 // -- rate(op(s1, s2)) = lcm(rate(s1), rate(s2))
675
676 vector<Tree> subsigs;
677 unsigned int n = getSubSignals(sig, subsigs, false);
678
679 if (n == 0) {
680 // -- rate(op()) = 1
681 *rate = 1;
682 E = nil;
683
684 } else {
685 // -- rate(op(s1, s2)) = lcm(rate(s1), rate(s2))
686
687 vector<int> subrates(n);
688 vector<Tree> subenvs(n);
689
690 int lcmrate = 1;
691 for (unsigned int i=0; i<n; i++) {
692 inferreRate(subsigs[i], &subrates[i], subenvs[i]);
693 lcmrate = lcm(subrates[i], lcmrate);
694 }
695
696 // Try to merge all (scaled) rate environments
697 Tree M = nil;
698 bool success = false;
699
700 for (unsigned int i=0; i<n; i++) {
701 M = mergeRateEnvironment(M, multRateEnv(lcmrate/subrates[i], subenvs[i]), success);
702 if (! success) {
703 // merge failed
704 *rate = 0; E = nil;
705 return;
706 }
707 }
708 // merge successful
709 *rate = lcmrate; E = M;
710 }
711 }
712 }
713
714
715 /**
716 * Try to add a rate environment E1 to a list of independent rate environments LE
717 * Returns a list of independent rate environments
718 */
719 static Tree addToMultiRates(Tree E1, Tree LE, bool& success);
720 static Tree TRACED_addToMultiRates(Tree E1, Tree LE, bool& success);
721
722 static Tree addToMultiRates(Tree E1, Tree LE, bool& success)
723 {
724 TRACE(cerr << ++TABBER << "addToMultiRates(" << *E1 << ", " << *LE << ")" << endl);
725 Tree result = TRACED_addToMultiRates(E1, LE, success);
726 if (success) {
727 TRACE(cerr << --TABBER << "addToMultiRates(" << *E1 << ", " << *LE << ") -> " << *result << endl);
728 } else {
729 TRACE(cerr << --TABBER << "addToMultiRates(" << *E1 << ", " << *LE << ") -> FAILED" << endl);
730 }
731 return result;
732 }
733
734
735 static Tree TRACED_addToMultiRates(Tree E1, Tree LE, bool& success)
736 {
737 if (isNil(LE)) {
738 success = true;
739 return cons(E1,nil);
740 } else {
741 Tree E2 = hd(LE);
742 if (areRatesIndependent(E1,E2)) {
743 return cons(E2, addToMultiRates(E1, tl(LE), success));
744 } else {
745 int n1, n2;
746 if (areRatesCompatible(E1, E2, n1, n2)) {
747 Tree M = mergeRateEnvironment(multRateEnv(n1,E1), multRateEnv(n2,E2), success);
748 if (success) {
749 return addToMultiRates(M, tl(LE), success);
750 } else {
751 return nil;
752 }
753 } else {
754 return nil;
755 }
756 }
757 }
758 }
759
760
761
762 RateInferrer::RateInferrer(Tree lsig)
763 {
764 TRACE(cerr << "ENTRE RateInferrer constructor of " << *lsig << endl);
765 if (! (isList(lsig) | isNil(lsig))) {
766 lsig = cons(lsig,nil);
767 }
768 fFullList = addRecursiveSignals(lsig);
769 fRateEnv = inferreMultiRates(lsig, fSuccess);
770 if (fSuccess) {
771 // nit the rate properties for the expressions in the environment
772 for (Tree L=fRateEnv; isList(L); L = tl(L)) {
773 Tree p = hd(L);
774 fRateProperty.set(hd(p),tree2int(tl(p)));
775 }
776 }
777 TRACE(cerr << "EXIT RateInferrer constructor" << *lsig << endl);
778 }
779
780 // returns the rate of sig assuming that sig is a subexpression of lsig
781 int RateInferrer::rate(Tree sig)
782 {
783 int r;
784
785 if (!fSuccess) {
786 return 0;
787 } else if (fRateProperty.get(sig, r)) {
788 return r;
789 } else {
790 r = computeRate(sig);
791 fRateProperty.set(sig, r);
792 return r;
793 }
794 }
795
796 int RateInferrer::computeRate(Tree sig)
797 {
798 Tree n, x, rsig, id, body;
799 int i;
800
801 if ( isSigInput(sig, &i)) {
802
803 TRACE(cerr << "ERROR: Input " << i << " should have a rate" << endl);
804 return 0;
805
806 } else if ( isProj(sig,&i,rsig) && isRec(rsig, id, body) ) {
807
808 TRACE(cerr << "ERROR: Recursive signal " << *sig << " should have a rate" << endl);
809 return 0;
810
811 } else if ( isSigVectorize(sig, n, x) ) {
812
813 VectorType* vt = isVectorType(getCertifiedSigType(sig));
814 assert(vt);
815 return rate(x) / vt->size();
816
817 } else if ( isSigSerialize(sig, x)) {
818
819 VectorType* vt = isVectorType(getCertifiedSigType(x));
820 assert(vt);
821 return vt->size() * rate(x);
822
823 } else if ( isSigUpSample(sig, n, x) ) {
824
825 int i = checkSignalDenotesSize(n,sig);
826 return rate(x) * i;
827
828 } else if ( isSigDownSample(sig, n, x) ) {
829
830 int i = checkSignalDenotesSize(n,sig);
831 int r = rate(x);
832 assert(r%i == 0);
833 return r/i;
834
835 } else {
836
837 vector<Tree> subsigs;
838 vector<int> subrates;
839 int n = getSubSignals(sig, subsigs, false);
840 if (n == 0) {
841 // we don't depend of any subsignals, then the rate is 1
842 return 1;
843 } else {
844 // we depend on subsignals, the rate is the highest one
845 // moreover the highest one is a multiple of all other
846 // rates
847 int maxrate = 1;
848 int lcmrate = 1;
849 for (unsigned int i=0; i<subsigs.size(); i++) {
850 int r = rate(subsigs[i]);
851 maxrate = max(r, maxrate);
852 lcmrate = lcm(r, lcmrate);
853 if (lcmrate != maxrate) {
854 return 0; // rates of arguments are incompatible
855 }
856 }
857 return maxrate;
858 }
859 }
860 }
861
862