134c43f08b441672ef83d6656765a084ff6a22b1
[libav.git] / libavcodec / eval.c
1 /*
2 * simple arithmetic expression evaluator
3 *
4 * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
5 * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 /**
25 * @file libavcodec/eval.c
26 * simple arithmetic expression evaluator.
27 *
28 * see http://joe.hotchkiss.com/programming/eval/eval.html
29 */
30
31 #include <stdio.h>
32 #include <stdlib.h>
33 #include <string.h>
34 #include <math.h>
35
36 #include "libavutil/mathematics.h"
37 #include "avcodec.h"
38 #include "eval.h"
39
40 typedef struct Parser{
41 int stack_index;
42 char *s;
43 const double *const_value;
44 const char * const *const_name; // NULL terminated
45 double (**func1)(void *, double a); // NULL terminated
46 const char **func1_name; // NULL terminated
47 double (**func2)(void *, double a, double b); // NULL terminated
48 const char **func2_name; // NULL terminated
49 void *opaque;
50 const char **error;
51 #define VARS 10
52 double var[VARS];
53 } Parser;
54
55 static const int8_t si_prefixes['z' - 'E' + 1]={
56 ['y'-'E']= -24,
57 ['z'-'E']= -21,
58 ['a'-'E']= -18,
59 ['f'-'E']= -15,
60 ['p'-'E']= -12,
61 ['n'-'E']= - 9,
62 ['u'-'E']= - 6,
63 ['m'-'E']= - 3,
64 ['c'-'E']= - 2,
65 ['d'-'E']= - 1,
66 ['h'-'E']= 2,
67 ['k'-'E']= 3,
68 ['K'-'E']= 3,
69 ['M'-'E']= 6,
70 ['G'-'E']= 9,
71 ['T'-'E']= 12,
72 ['P'-'E']= 15,
73 ['E'-'E']= 18,
74 ['Z'-'E']= 21,
75 ['Y'-'E']= 24,
76 };
77
78 double av_strtod(const char *numstr, char **tail) {
79 double d;
80 char *next;
81 d = strtod(numstr, &next);
82 /* if parsing succeeded, check for and interpret postfixes */
83 if (next!=numstr) {
84
85 if(*next >= 'E' && *next <= 'z'){
86 int e= si_prefixes[*next - 'E'];
87 if(e){
88 if(next[1] == 'i'){
89 d*= pow( 2, e/0.3);
90 next+=2;
91 }else{
92 d*= pow(10, e);
93 next++;
94 }
95 }
96 }
97
98 if(*next=='B') {
99 d*=8;
100 next++;
101 }
102 }
103 /* if requested, fill in tail with the position after the last parsed
104 character */
105 if (tail)
106 *tail = next;
107 return d;
108 }
109
110 static int strmatch(const char *s, const char *prefix){
111 int i;
112 for(i=0; prefix[i]; i++){
113 if(prefix[i] != s[i]) return 0;
114 }
115 return 1;
116 }
117
118 struct ff_expr_s {
119 enum {
120 e_value, e_const, e_func0, e_func1, e_func2,
121 e_squish, e_gauss, e_ld,
122 e_mod, e_max, e_min, e_eq, e_gt, e_gte,
123 e_pow, e_mul, e_div, e_add,
124 e_last, e_st, e_while,
125 } type;
126 double value; // is sign in other types
127 union {
128 int const_index;
129 double (*func0)(double);
130 double (*func1)(void *, double);
131 double (*func2)(void *, double, double);
132 } a;
133 AVEvalExpr * param[2];
134 };
135
136 static double eval_expr(Parser * p, AVEvalExpr * e) {
137 switch (e->type) {
138 case e_value: return e->value;
139 case e_const: return e->value * p->const_value[e->a.const_index];
140 case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
141 case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
142 case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
143 case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
144 case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
145 case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
146 case e_while: {
147 double d = NAN;
148 while(eval_expr(p, e->param[0]))
149 d=eval_expr(p, e->param[1]);
150 return d;
151 }
152 default: {
153 double d = eval_expr(p, e->param[0]);
154 double d2 = eval_expr(p, e->param[1]);
155 switch (e->type) {
156 case e_mod: return e->value * (d - floor(d/d2)*d2);
157 case e_max: return e->value * (d > d2 ? d : d2);
158 case e_min: return e->value * (d < d2 ? d : d2);
159 case e_eq: return e->value * (d == d2 ? 1.0 : 0.0);
160 case e_gt: return e->value * (d > d2 ? 1.0 : 0.0);
161 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
162 case e_pow: return e->value * pow(d, d2);
163 case e_mul: return e->value * (d * d2);
164 case e_div: return e->value * (d / d2);
165 case e_add: return e->value * (d + d2);
166 case e_last:return e->value * d2;
167 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
168 }
169 }
170 }
171 return NAN;
172 }
173
174 static AVEvalExpr * parse_expr(Parser *p);
175
176 void ff_eval_free(AVEvalExpr * e) {
177 if (!e) return;
178 ff_eval_free(e->param[0]);
179 ff_eval_free(e->param[1]);
180 av_freep(&e);
181 }
182
183 static AVEvalExpr * parse_primary(Parser *p) {
184 AVEvalExpr * d = av_mallocz(sizeof(AVEvalExpr));
185 char *next= p->s;
186 int i;
187
188 if (!d)
189 return NULL;
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 return d;
197 }
198 d->value = 1;
199
200 /* named constants */
201 for(i=0; p->const_name && p->const_name[i]; i++){
202 if(strmatch(p->s, p->const_name[i])){
203 p->s+= strlen(p->const_name[i]);
204 d->type = e_const;
205 d->a.const_index = i;
206 return d;
207 }
208 }
209
210 p->s= strchr(p->s, '(');
211 if(p->s==NULL){
212 *p->error = "undefined constant or missing (";
213 p->s= next;
214 ff_eval_free(d);
215 return NULL;
216 }
217 p->s++; // "("
218 if (*next == '(') { // special case do-nothing
219 av_freep(&d);
220 d = parse_expr(p);
221 if(p->s[0] != ')'){
222 *p->error = "missing )";
223 ff_eval_free(d);
224 return NULL;
225 }
226 p->s++; // ")"
227 return d;
228 }
229 d->param[0] = parse_expr(p);
230 if(p->s[0]== ','){
231 p->s++; // ","
232 d->param[1] = parse_expr(p);
233 }
234 if(p->s[0] != ')'){
235 *p->error = "missing )";
236 ff_eval_free(d);
237 return NULL;
238 }
239 p->s++; // ")"
240
241 d->type = e_func0;
242 if( strmatch(next, "sinh" ) ) d->a.func0 = sinh;
243 else if( strmatch(next, "cosh" ) ) d->a.func0 = cosh;
244 else if( strmatch(next, "tanh" ) ) d->a.func0 = tanh;
245 else if( strmatch(next, "sin" ) ) d->a.func0 = sin;
246 else if( strmatch(next, "cos" ) ) d->a.func0 = cos;
247 else if( strmatch(next, "tan" ) ) d->a.func0 = tan;
248 else if( strmatch(next, "atan" ) ) d->a.func0 = atan;
249 else if( strmatch(next, "asin" ) ) d->a.func0 = asin;
250 else if( strmatch(next, "acos" ) ) d->a.func0 = acos;
251 else if( strmatch(next, "exp" ) ) d->a.func0 = exp;
252 else if( strmatch(next, "log" ) ) d->a.func0 = log;
253 else if( strmatch(next, "abs" ) ) d->a.func0 = fabs;
254 else if( strmatch(next, "squish") ) d->type = e_squish;
255 else if( strmatch(next, "gauss" ) ) d->type = e_gauss;
256 else if( strmatch(next, "mod" ) ) d->type = e_mod;
257 else if( strmatch(next, "max" ) ) d->type = e_max;
258 else if( strmatch(next, "min" ) ) d->type = e_min;
259 else if( strmatch(next, "eq" ) ) d->type = e_eq;
260 else if( strmatch(next, "gte" ) ) d->type = e_gte;
261 else if( strmatch(next, "gt" ) ) d->type = e_gt;
262 else if( strmatch(next, "lte" ) ) { AVEvalExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
263 else if( strmatch(next, "lt" ) ) { AVEvalExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
264 else if( strmatch(next, "ld" ) ) d->type = e_ld;
265 else if( strmatch(next, "st" ) ) d->type = e_st;
266 else if( strmatch(next, "while" ) ) d->type = e_while;
267 else {
268 for(i=0; p->func1_name && p->func1_name[i]; i++){
269 if(strmatch(next, p->func1_name[i])){
270 d->a.func1 = p->func1[i];
271 d->type = e_func1;
272 return d;
273 }
274 }
275
276 for(i=0; p->func2_name && p->func2_name[i]; i++){
277 if(strmatch(next, p->func2_name[i])){
278 d->a.func2 = p->func2[i];
279 d->type = e_func2;
280 return d;
281 }
282 }
283
284 *p->error = "unknown function";
285 ff_eval_free(d);
286 return NULL;
287 }
288
289 return d;
290 }
291
292 static AVEvalExpr * new_eval_expr(int type, int value, AVEvalExpr *p0, AVEvalExpr *p1){
293 AVEvalExpr * e = av_mallocz(sizeof(AVEvalExpr));
294 if (!e)
295 return NULL;
296 e->type =type ;
297 e->value =value ;
298 e->param[0] =p0 ;
299 e->param[1] =p1 ;
300 return e;
301 }
302
303 static AVEvalExpr * parse_pow(Parser *p, int *sign){
304 *sign= (*p->s == '+') - (*p->s == '-');
305 p->s += *sign&1;
306 return parse_primary(p);
307 }
308
309 static AVEvalExpr * parse_factor(Parser *p){
310 int sign, sign2;
311 AVEvalExpr * e = parse_pow(p, &sign);
312 while(p->s[0]=='^'){
313 p->s++;
314 e= new_eval_expr(e_pow, 1, e, parse_pow(p, &sign2));
315 if (!e)
316 return NULL;
317 if (e->param[1]) e->param[1]->value *= (sign2|1);
318 }
319 if (e) e->value *= (sign|1);
320 return e;
321 }
322
323 static AVEvalExpr * parse_term(Parser *p){
324 AVEvalExpr * e = parse_factor(p);
325 while(p->s[0]=='*' || p->s[0]=='/'){
326 int c= *p->s++;
327 e= new_eval_expr(c == '*' ? e_mul : e_div, 1, e, parse_factor(p));
328 if (!e)
329 return NULL;
330 }
331 return e;
332 }
333
334 static AVEvalExpr * parse_subexpr(Parser *p) {
335 AVEvalExpr * e = parse_term(p);
336 while(*p->s == '+' || *p->s == '-') {
337 e= new_eval_expr(e_add, 1, e, parse_term(p));
338 if (!e)
339 return NULL;
340 };
341
342 return e;
343 }
344
345 static AVEvalExpr * parse_expr(Parser *p) {
346 AVEvalExpr * e;
347
348 if(p->stack_index <= 0) //protect against stack overflows
349 return NULL;
350 p->stack_index--;
351
352 e = parse_subexpr(p);
353
354 while(*p->s == ';') {
355 p->s++;
356 e= new_eval_expr(e_last, 1, e, parse_subexpr(p));
357 if (!e)
358 return NULL;
359 };
360
361 p->stack_index++;
362
363 return e;
364 }
365
366 static int verify_expr(AVEvalExpr * e) {
367 if (!e) return 0;
368 switch (e->type) {
369 case e_value:
370 case e_const: return 1;
371 case e_func0:
372 case e_func1:
373 case e_squish:
374 case e_ld:
375 case e_gauss: return verify_expr(e->param[0]);
376 default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
377 }
378 }
379
380 AVEvalExpr * ff_parse(const char *s, const char * const *const_name,
381 double (**func1)(void *, double), const char **func1_name,
382 double (**func2)(void *, double, double), const char **func2_name,
383 const char **error){
384 Parser p;
385 AVEvalExpr *e = NULL;
386 char *w = av_malloc(strlen(s) + 1);
387 char *wp = w;
388
389 if (!w)
390 goto end;
391
392 while (*s)
393 if (!isspace(*s++)) *wp++ = s[-1];
394 *wp++ = 0;
395
396 p.stack_index=100;
397 p.s= w;
398 p.const_name = const_name;
399 p.func1 = func1;
400 p.func1_name = func1_name;
401 p.func2 = func2;
402 p.func2_name = func2_name;
403 p.error= error;
404
405 e = parse_expr(&p);
406 if (!verify_expr(e)) {
407 ff_eval_free(e);
408 e = NULL;
409 }
410 end:
411 av_free(w);
412 return e;
413 }
414
415 double ff_parse_eval(AVEvalExpr * e, const double *const_value, void *opaque) {
416 Parser p;
417
418 p.const_value= const_value;
419 p.opaque = opaque;
420 return eval_expr(&p, e);
421 }
422
423 double ff_eval2(const char *s, const double *const_value, const char * const *const_name,
424 double (**func1)(void *, double), const char **func1_name,
425 double (**func2)(void *, double, double), const char **func2_name,
426 void *opaque, const char **error){
427 AVEvalExpr * e = ff_parse(s, const_name, func1, func1_name, func2, func2_name, error);
428 double d;
429 if (!e) return NAN;
430 d = ff_parse_eval(e, const_value, opaque);
431 ff_eval_free(e);
432 return d;
433 }
434
435 #ifdef TEST
436 #undef printf
437 static double const_values[]={
438 M_PI,
439 M_E,
440 0
441 };
442 static const char *const_names[]={
443 "PI",
444 "E",
445 0
446 };
447 int main(void){
448 int i;
449 printf("%f == 12.7\n", ff_eval2("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_values, const_names, NULL, NULL, NULL, NULL, NULL, NULL));
450 printf("%f == 0.931322575\n", ff_eval2("80G/80Gi", const_values, const_names, NULL, NULL, NULL, NULL, NULL, NULL));
451
452 for(i=0; i<1050; i++){
453 START_TIMER
454 ff_eval2("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_values, const_names, NULL, NULL, NULL, NULL, NULL, NULL);
455 STOP_TIMER("ff_eval2")
456 }
457 return 0;
458 }
459 #endif