2a8fc442aa73849cb37b44db5958b40f255e1df5
[libav.git] / libavcodec / eval.c
1 /*
2 * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
3 * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * simple arithmetic expression evaluator.
25 *
26 * see http://joe.hotchkiss.com/programming/eval/eval.html
27 */
28
29 #include "libavutil/avutil.h"
30 #include "eval.h"
31
32 typedef struct Parser {
33 const AVClass *class;
34 int stack_index;
35 char *s;
36 const double *const_values;
37 const char * const *const_names; // NULL terminated
38 double (* const *funcs1)(void *, double a); // NULL terminated
39 const char * const *func1_names; // NULL terminated
40 double (* const *funcs2)(void *, double a, double b); // NULL terminated
41 const char * const *func2_names; // NULL terminated
42 void *opaque;
43 int log_offset;
44 void *log_ctx;
45 #define VARS 10
46 double var[VARS];
47 } Parser;
48
49 static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };
50
51 static const int8_t si_prefixes['z' - 'E' + 1] = {
52 ['y'-'E']= -24,
53 ['z'-'E']= -21,
54 ['a'-'E']= -18,
55 ['f'-'E']= -15,
56 ['p'-'E']= -12,
57 ['n'-'E']= - 9,
58 ['u'-'E']= - 6,
59 ['m'-'E']= - 3,
60 ['c'-'E']= - 2,
61 ['d'-'E']= - 1,
62 ['h'-'E']= 2,
63 ['k'-'E']= 3,
64 ['K'-'E']= 3,
65 ['M'-'E']= 6,
66 ['G'-'E']= 9,
67 ['T'-'E']= 12,
68 ['P'-'E']= 15,
69 ['E'-'E']= 18,
70 ['Z'-'E']= 21,
71 ['Y'-'E']= 24,
72 };
73
74 double av_strtod(const char *numstr, char **tail)
75 {
76 double d;
77 char *next;
78 d = strtod(numstr, &next);
79 /* if parsing succeeded, check for and interpret postfixes */
80 if (next!=numstr) {
81 if (*next >= 'E' && *next <= 'z') {
82 int e= si_prefixes[*next - 'E'];
83 if (e) {
84 if (next[1] == 'i') {
85 d*= pow( 2, e/0.3);
86 next+=2;
87 } else {
88 d*= pow(10, e);
89 next++;
90 }
91 }
92 }
93
94 if (*next=='B') {
95 d*=8;
96 next++;
97 }
98 }
99 /* if requested, fill in tail with the position after the last parsed
100 character */
101 if (tail)
102 *tail = next;
103 return d;
104 }
105
106 static int strmatch(const char *s, const char *prefix)
107 {
108 int i;
109 for (i=0; prefix[i]; i++) {
110 if (prefix[i] != s[i]) return 0;
111 }
112 return 1;
113 }
114
115 struct AVExpr {
116 enum {
117 e_value, e_const, e_func0, e_func1, e_func2,
118 e_squish, e_gauss, e_ld,
119 e_mod, e_max, e_min, e_eq, e_gt, e_gte,
120 e_pow, e_mul, e_div, e_add,
121 e_last, e_st, e_while,
122 } type;
123 double value; // is sign in other types
124 union {
125 int const_index;
126 double (*func0)(double);
127 double (*func1)(void *, double);
128 double (*func2)(void *, double, double);
129 } a;
130 struct AVExpr *param[2];
131 };
132
133 static double eval_expr(Parser *p, AVExpr *e)
134 {
135 switch (e->type) {
136 case e_value: return e->value;
137 case e_const: return e->value * p->const_values[e->a.const_index];
138 case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
139 case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
140 case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
141 case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
142 case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
143 case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
144 case e_while: {
145 double d = NAN;
146 while (eval_expr(p, e->param[0]))
147 d=eval_expr(p, e->param[1]);
148 return d;
149 }
150 default: {
151 double d = eval_expr(p, e->param[0]);
152 double d2 = eval_expr(p, e->param[1]);
153 switch (e->type) {
154 case e_mod: return e->value * (d - floor(d/d2)*d2);
155 case e_max: return e->value * (d > d2 ? d : d2);
156 case e_min: return e->value * (d < d2 ? d : d2);
157 case e_eq: return e->value * (d == d2 ? 1.0 : 0.0);
158 case e_gt: return e->value * (d > d2 ? 1.0 : 0.0);
159 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
160 case e_pow: return e->value * pow(d, d2);
161 case e_mul: return e->value * (d * d2);
162 case e_div: return e->value * (d / d2);
163 case e_add: return e->value * (d + d2);
164 case e_last:return e->value * d2;
165 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
166 }
167 }
168 }
169 return NAN;
170 }
171
172 static int parse_expr(AVExpr **e, Parser *p);
173
174 void ff_free_expr(AVExpr *e)
175 {
176 if (!e) return;
177 ff_free_expr(e->param[0]);
178 ff_free_expr(e->param[1]);
179 av_freep(&e);
180 }
181
182 static int parse_primary(AVExpr **e, Parser *p)
183 {
184 AVExpr *d = av_mallocz(sizeof(AVExpr));
185 char *next= p->s;
186 int ret, i;
187
188 if (!d)
189 return AVERROR(ENOMEM);
190
191 /* number */
192 d->value = av_strtod(p->s, &next);
193 if (next != p->s) {
194 d->type = e_value;
195 p->s= next;
196 *e = d;
197 return 0;
198 }
199 d->value = 1;
200
201 /* named constants */
202 for (i=0; p->const_names && p->const_names[i]; i++) {
203 if (strmatch(p->s, p->const_names[i])) {
204 p->s+= strlen(p->const_names[i]);
205 d->type = e_const;
206 d->a.const_index = i;
207 *e = d;
208 return 0;
209 }
210 }
211
212 p->s= strchr(p->s, '(');
213 if (p->s==NULL) {
214 av_log(p, AV_LOG_ERROR, "undefined constant or missing (\n");
215 p->s= next;
216 ff_free_expr(d);
217 return AVERROR(EINVAL);
218 }
219 p->s++; // "("
220 if (*next == '(') { // special case do-nothing
221 av_freep(&d);
222 if ((ret = parse_expr(&d, p)) < 0)
223 return ret;
224 if (p->s[0] != ')') {
225 av_log(p, AV_LOG_ERROR, "missing )\n");
226 ff_free_expr(d);
227 return AVERROR(EINVAL);
228 }
229 p->s++; // ")"
230 *e = d;
231 return 0;
232 }
233 if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
234 ff_free_expr(d);
235 return ret;
236 }
237 if (p->s[0]== ',') {
238 p->s++; // ","
239 parse_expr(&d->param[1], p);
240 }
241 if (p->s[0] != ')') {
242 av_log(p, AV_LOG_ERROR, "missing )\n");
243 ff_free_expr(d);
244 return AVERROR(EINVAL);
245 }
246 p->s++; // ")"
247
248 d->type = e_func0;
249 if (strmatch(next, "sinh" )) d->a.func0 = sinh;
250 else if (strmatch(next, "cosh" )) d->a.func0 = cosh;
251 else if (strmatch(next, "tanh" )) d->a.func0 = tanh;
252 else if (strmatch(next, "sin" )) d->a.func0 = sin;
253 else if (strmatch(next, "cos" )) d->a.func0 = cos;
254 else if (strmatch(next, "tan" )) d->a.func0 = tan;
255 else if (strmatch(next, "atan" )) d->a.func0 = atan;
256 else if (strmatch(next, "asin" )) d->a.func0 = asin;
257 else if (strmatch(next, "acos" )) d->a.func0 = acos;
258 else if (strmatch(next, "exp" )) d->a.func0 = exp;
259 else if (strmatch(next, "log" )) d->a.func0 = log;
260 else if (strmatch(next, "abs" )) d->a.func0 = fabs;
261 else if (strmatch(next, "squish")) d->type = e_squish;
262 else if (strmatch(next, "gauss" )) d->type = e_gauss;
263 else if (strmatch(next, "mod" )) d->type = e_mod;
264 else if (strmatch(next, "max" )) d->type = e_max;
265 else if (strmatch(next, "min" )) d->type = e_min;
266 else if (strmatch(next, "eq" )) d->type = e_eq;
267 else if (strmatch(next, "gte" )) d->type = e_gte;
268 else if (strmatch(next, "gt" )) d->type = e_gt;
269 else if (strmatch(next, "lte" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
270 else if (strmatch(next, "lt" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
271 else if (strmatch(next, "ld" )) d->type = e_ld;
272 else if (strmatch(next, "st" )) d->type = e_st;
273 else if (strmatch(next, "while" )) d->type = e_while;
274 else {
275 for (i=0; p->func1_names && p->func1_names[i]; i++) {
276 if (strmatch(next, p->func1_names[i])) {
277 d->a.func1 = p->funcs1[i];
278 d->type = e_func1;
279 *e = d;
280 return 0;
281 }
282 }
283
284 for (i=0; p->func2_names && p->func2_names[i]; i++) {
285 if (strmatch(next, p->func2_names[i])) {
286 d->a.func2 = p->funcs2[i];
287 d->type = e_func2;
288 *e = d;
289 return 0;
290 }
291 }
292
293 av_log(p, AV_LOG_ERROR, "unknown function\n");
294 ff_free_expr(d);
295 return AVERROR(EINVAL);
296 }
297
298 *e = d;
299 return 0;
300 }
301
302 static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
303 {
304 AVExpr *e = av_mallocz(sizeof(AVExpr));
305 if (!e)
306 return NULL;
307 e->type =type ;
308 e->value =value ;
309 e->param[0] =p0 ;
310 e->param[1] =p1 ;
311 return e;
312 }
313
314 static int parse_pow(AVExpr **e, Parser *p, int *sign)
315 {
316 *sign= (*p->s == '+') - (*p->s == '-');
317 p->s += *sign&1;
318 return parse_primary(e, p);
319 }
320
321 static int parse_factor(AVExpr **e, Parser *p)
322 {
323 int sign, sign2, ret;
324 AVExpr *e0, *e1, *e2;
325 if ((ret = parse_pow(&e0, p, &sign)) < 0)
326 return ret;
327 while(p->s[0]=='^'){
328 e1 = e0;
329 p->s++;
330 if ((ret = parse_pow(&e2, p, &sign2)) < 0) {
331 ff_free_expr(e1);
332 return ret;
333 }
334 e0 = new_eval_expr(e_pow, 1, e1, e2);
335 if (!e0) {
336 ff_free_expr(e1);
337 ff_free_expr(e2);
338 return AVERROR(ENOMEM);
339 }
340 if (e0->param[1]) e0->param[1]->value *= (sign2|1);
341 }
342 if (e0) e0->value *= (sign|1);
343
344 *e = e0;
345 return 0;
346 }
347
348 static int parse_term(AVExpr **e, Parser *p)
349 {
350 int ret;
351 AVExpr *e0, *e1, *e2;
352 if ((ret = parse_factor(&e0, p)) < 0)
353 return ret;
354 while (p->s[0]=='*' || p->s[0]=='/') {
355 int c= *p->s++;
356 e1 = e0;
357 if ((ret = parse_factor(&e2, p)) < 0) {
358 ff_free_expr(e1);
359 return ret;
360 }
361 e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
362 if (!e0) {
363 ff_free_expr(e1);
364 ff_free_expr(e2);
365 return AVERROR(ENOMEM);
366 }
367 }
368 *e = e0;
369 return 0;
370 }
371
372 static int parse_subexpr(AVExpr **e, Parser *p)
373 {
374 int ret;
375 AVExpr *e0, *e1, *e2;
376 if ((ret = parse_term(&e0, p)) < 0)
377 return ret;
378 while (*p->s == '+' || *p->s == '-') {
379 e1 = e0;
380 if ((ret = parse_term(&e2, p)) < 0) {
381 ff_free_expr(e1);
382 return ret;
383 }
384 e0 = new_eval_expr(e_add, 1, e1, e2);
385 if (!e0) {
386 ff_free_expr(e1);
387 ff_free_expr(e2);
388 return AVERROR(ENOMEM);
389 }
390 };
391
392 *e = e0;
393 return 0;
394 }
395
396 static int parse_expr(AVExpr **e, Parser *p)
397 {
398 int ret;
399 AVExpr *e0, *e1, *e2;
400 if (p->stack_index <= 0) //protect against stack overflows
401 return AVERROR(EINVAL);
402 p->stack_index--;
403
404 if ((ret = parse_subexpr(&e0, p)) < 0)
405 return ret;
406 while (*p->s == ';') {
407 e1 = e0;
408 if ((ret = parse_subexpr(&e2, p)) < 0) {
409 ff_free_expr(e1);
410 return ret;
411 }
412 p->s++;
413 e0 = new_eval_expr(e_last, 1, e1, e2);
414 if (!e0) {
415 ff_free_expr(e1);
416 ff_free_expr(e2);
417 return AVERROR(ENOMEM);
418 }
419 };
420
421 p->stack_index++;
422 *e = e0;
423 return 0;
424 }
425
426 static int verify_expr(AVExpr *e)
427 {
428 if (!e) return 0;
429 switch (e->type) {
430 case e_value:
431 case e_const: return 1;
432 case e_func0:
433 case e_func1:
434 case e_squish:
435 case e_ld:
436 case e_gauss: return verify_expr(e->param[0]);
437 default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
438 }
439 }
440
441 int ff_parse_expr(AVExpr **expr, const char *s,
442 const char * const *const_names,
443 const char * const *func1_names, double (* const *funcs1)(void *, double),
444 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
445 int log_offset, void *log_ctx)
446 {
447 Parser p;
448 AVExpr *e = NULL;
449 char *w = av_malloc(strlen(s) + 1);
450 char *wp = w;
451 int ret = 0;
452
453 if (!w)
454 return AVERROR(ENOMEM);
455
456 while (*s)
457 if (!isspace(*s++)) *wp++ = s[-1];
458 *wp++ = 0;
459
460 p.class = &class;
461 p.stack_index=100;
462 p.s= w;
463 p.const_names = const_names;
464 p.funcs1 = funcs1;
465 p.func1_names = func1_names;
466 p.funcs2 = funcs2;
467 p.func2_names = func2_names;
468 p.log_offset = log_offset;
469 p.log_ctx = log_ctx;
470
471 if ((ret = parse_expr(&e, &p)) < 0)
472 goto end;
473 if (!verify_expr(e)) {
474 ff_free_expr(e);
475 ret = AVERROR(EINVAL);
476 goto end;
477 }
478 *expr = e;
479 end:
480 av_free(w);
481 return ret;
482 }
483
484 double ff_eval_expr(AVExpr *e, const double *const_values, void *opaque)
485 {
486 Parser p;
487
488 p.const_values = const_values;
489 p.opaque = opaque;
490 return eval_expr(&p, e);
491 }
492
493 int ff_parse_and_eval_expr(double *d, const char *s,
494 const char * const *const_names, const double *const_values,
495 const char * const *func1_names, double (* const *funcs1)(void *, double),
496 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
497 void *opaque, int log_offset, void *log_ctx)
498 {
499 AVExpr *e = NULL;
500 int ret = ff_parse_expr(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
501
502 if (ret < 0) {
503 *d = NAN;
504 return ret;
505 }
506 *d = ff_eval_expr(e, const_values, opaque);
507 ff_free_expr(e);
508 return isnan(*d) ? AVERROR(EINVAL) : 0;
509 }
510
511 #ifdef TEST
512 #undef printf
513 static double const_values[] = {
514 M_PI,
515 M_E,
516 0
517 };
518
519 static const char *const_names[] = {
520 "PI",
521 "E",
522 0
523 };
524
525 int main(void)
526 {
527 int i;
528 double d;
529 ff_parse_and_eval_expr(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
530 const_names, const_values,
531 NULL, NULL, NULL, NULL, NULL, 0, NULL);
532 printf("%f == 12.7\n", d);
533 ff_parse_and_eval_expr(&d, "80G/80Gi",
534 const_names, const_values,
535 NULL, NULL, NULL, NULL, NULL, 0, NULL);
536 printf("%f == 0.931322575\n", d);
537
538 for (i=0; i<1050; i++) {
539 START_TIMER
540 ff_parse_and_eval_expr(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
541 const_names, const_values,
542 NULL, NULL, NULL, NULL, NULL, 0, NULL);
543 STOP_TIMER("ff_parse_and_eval_expr")
544 }
545 return 0;
546 }
547 #endif