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[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 int stack_index;
34 char *s;
35 const double *const_value;
36 const char * const *const_name; // NULL terminated
37 double (* const *func1)(void *, double a); // NULL terminated
38 const char * const *func1_name; // NULL terminated
39 double (* const *func2)(void *, double a, double b); // NULL terminated
40 const char * const *func2_name; // NULL terminated
41 void *opaque;
42 const char **error;
43 #define VARS 10
44 double var[VARS];
45 } Parser;
46
47 static const int8_t si_prefixes['z' - 'E' + 1]={
48 ['y'-'E']= -24,
49 ['z'-'E']= -21,
50 ['a'-'E']= -18,
51 ['f'-'E']= -15,
52 ['p'-'E']= -12,
53 ['n'-'E']= - 9,
54 ['u'-'E']= - 6,
55 ['m'-'E']= - 3,
56 ['c'-'E']= - 2,
57 ['d'-'E']= - 1,
58 ['h'-'E']= 2,
59 ['k'-'E']= 3,
60 ['K'-'E']= 3,
61 ['M'-'E']= 6,
62 ['G'-'E']= 9,
63 ['T'-'E']= 12,
64 ['P'-'E']= 15,
65 ['E'-'E']= 18,
66 ['Z'-'E']= 21,
67 ['Y'-'E']= 24,
68 };
69
70 double av_strtod(const char *numstr, char **tail) {
71 double d;
72 char *next;
73 d = strtod(numstr, &next);
74 /* if parsing succeeded, check for and interpret postfixes */
75 if (next!=numstr) {
76
77 if(*next >= 'E' && *next <= 'z'){
78 int e= si_prefixes[*next - 'E'];
79 if(e){
80 if(next[1] == 'i'){
81 d*= pow( 2, e/0.3);
82 next+=2;
83 }else{
84 d*= pow(10, e);
85 next++;
86 }
87 }
88 }
89
90 if(*next=='B') {
91 d*=8;
92 next++;
93 }
94 }
95 /* if requested, fill in tail with the position after the last parsed
96 character */
97 if (tail)
98 *tail = next;
99 return d;
100 }
101
102 static int strmatch(const char *s, const char *prefix){
103 int i;
104 for(i=0; prefix[i]; i++){
105 if(prefix[i] != s[i]) return 0;
106 }
107 return 1;
108 }
109
110 struct AVExpr {
111 enum {
112 e_value, e_const, e_func0, e_func1, e_func2,
113 e_squish, e_gauss, e_ld,
114 e_mod, e_max, e_min, e_eq, e_gt, e_gte,
115 e_pow, e_mul, e_div, e_add,
116 e_last, e_st, e_while,
117 } type;
118 double value; // is sign in other types
119 union {
120 int const_index;
121 double (*func0)(double);
122 double (*func1)(void *, double);
123 double (*func2)(void *, double, double);
124 } a;
125 struct AVExpr *param[2];
126 };
127
128 static double eval_expr(Parser * p, AVExpr * e) {
129 switch (e->type) {
130 case e_value: return e->value;
131 case e_const: return e->value * p->const_value[e->a.const_index];
132 case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
133 case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
134 case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
135 case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
136 case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
137 case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
138 case e_while: {
139 double d = NAN;
140 while(eval_expr(p, e->param[0]))
141 d=eval_expr(p, e->param[1]);
142 return d;
143 }
144 default: {
145 double d = eval_expr(p, e->param[0]);
146 double d2 = eval_expr(p, e->param[1]);
147 switch (e->type) {
148 case e_mod: return e->value * (d - floor(d/d2)*d2);
149 case e_max: return e->value * (d > d2 ? d : d2);
150 case e_min: return e->value * (d < d2 ? d : d2);
151 case e_eq: return e->value * (d == d2 ? 1.0 : 0.0);
152 case e_gt: return e->value * (d > d2 ? 1.0 : 0.0);
153 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
154 case e_pow: return e->value * pow(d, d2);
155 case e_mul: return e->value * (d * d2);
156 case e_div: return e->value * (d / d2);
157 case e_add: return e->value * (d + d2);
158 case e_last:return e->value * d2;
159 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
160 }
161 }
162 }
163 return NAN;
164 }
165
166 static AVExpr * parse_expr(Parser *p);
167
168 void ff_free_expr(AVExpr * e) {
169 if (!e) return;
170 ff_free_expr(e->param[0]);
171 ff_free_expr(e->param[1]);
172 av_freep(&e);
173 }
174
175 static AVExpr * parse_primary(Parser *p) {
176 AVExpr * d = av_mallocz(sizeof(AVExpr));
177 char *next= p->s;
178 int i;
179
180 if (!d)
181 return NULL;
182
183 /* number */
184 d->value = av_strtod(p->s, &next);
185 if(next != p->s){
186 d->type = e_value;
187 p->s= next;
188 return d;
189 }
190 d->value = 1;
191
192 /* named constants */
193 for(i=0; p->const_name && p->const_name[i]; i++){
194 if(strmatch(p->s, p->const_name[i])){
195 p->s+= strlen(p->const_name[i]);
196 d->type = e_const;
197 d->a.const_index = i;
198 return d;
199 }
200 }
201
202 p->s= strchr(p->s, '(');
203 if(p->s==NULL){
204 *p->error = "undefined constant or missing (";
205 p->s= next;
206 ff_free_expr(d);
207 return NULL;
208 }
209 p->s++; // "("
210 if (*next == '(') { // special case do-nothing
211 av_freep(&d);
212 d = parse_expr(p);
213 if(p->s[0] != ')'){
214 *p->error = "missing )";
215 ff_free_expr(d);
216 return NULL;
217 }
218 p->s++; // ")"
219 return d;
220 }
221 d->param[0] = parse_expr(p);
222 if(p->s[0]== ','){
223 p->s++; // ","
224 d->param[1] = parse_expr(p);
225 }
226 if(p->s[0] != ')'){
227 *p->error = "missing )";
228 ff_free_expr(d);
229 return NULL;
230 }
231 p->s++; // ")"
232
233 d->type = e_func0;
234 if( strmatch(next, "sinh" ) ) d->a.func0 = sinh;
235 else if( strmatch(next, "cosh" ) ) d->a.func0 = cosh;
236 else if( strmatch(next, "tanh" ) ) d->a.func0 = tanh;
237 else if( strmatch(next, "sin" ) ) d->a.func0 = sin;
238 else if( strmatch(next, "cos" ) ) d->a.func0 = cos;
239 else if( strmatch(next, "tan" ) ) d->a.func0 = tan;
240 else if( strmatch(next, "atan" ) ) d->a.func0 = atan;
241 else if( strmatch(next, "asin" ) ) d->a.func0 = asin;
242 else if( strmatch(next, "acos" ) ) d->a.func0 = acos;
243 else if( strmatch(next, "exp" ) ) d->a.func0 = exp;
244 else if( strmatch(next, "log" ) ) d->a.func0 = log;
245 else if( strmatch(next, "abs" ) ) d->a.func0 = fabs;
246 else if( strmatch(next, "squish") ) d->type = e_squish;
247 else if( strmatch(next, "gauss" ) ) d->type = e_gauss;
248 else if( strmatch(next, "mod" ) ) d->type = e_mod;
249 else if( strmatch(next, "max" ) ) d->type = e_max;
250 else if( strmatch(next, "min" ) ) d->type = e_min;
251 else if( strmatch(next, "eq" ) ) d->type = e_eq;
252 else if( strmatch(next, "gte" ) ) d->type = e_gte;
253 else if( strmatch(next, "gt" ) ) d->type = e_gt;
254 else if( strmatch(next, "lte" ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
255 else if( strmatch(next, "lt" ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
256 else if( strmatch(next, "ld" ) ) d->type = e_ld;
257 else if( strmatch(next, "st" ) ) d->type = e_st;
258 else if( strmatch(next, "while" ) ) d->type = e_while;
259 else {
260 for(i=0; p->func1_name && p->func1_name[i]; i++){
261 if(strmatch(next, p->func1_name[i])){
262 d->a.func1 = p->func1[i];
263 d->type = e_func1;
264 return d;
265 }
266 }
267
268 for(i=0; p->func2_name && p->func2_name[i]; i++){
269 if(strmatch(next, p->func2_name[i])){
270 d->a.func2 = p->func2[i];
271 d->type = e_func2;
272 return d;
273 }
274 }
275
276 *p->error = "unknown function";
277 ff_free_expr(d);
278 return NULL;
279 }
280
281 return d;
282 }
283
284 static AVExpr * new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1){
285 AVExpr * e = av_mallocz(sizeof(AVExpr));
286 if (!e)
287 return NULL;
288 e->type =type ;
289 e->value =value ;
290 e->param[0] =p0 ;
291 e->param[1] =p1 ;
292 return e;
293 }
294
295 static AVExpr * parse_pow(Parser *p, int *sign){
296 *sign= (*p->s == '+') - (*p->s == '-');
297 p->s += *sign&1;
298 return parse_primary(p);
299 }
300
301 static AVExpr * parse_factor(Parser *p){
302 int sign, sign2;
303 AVExpr * e = parse_pow(p, &sign);
304 while(p->s[0]=='^'){
305 p->s++;
306 e= new_eval_expr(e_pow, 1, e, parse_pow(p, &sign2));
307 if (!e)
308 return NULL;
309 if (e->param[1]) e->param[1]->value *= (sign2|1);
310 }
311 if (e) e->value *= (sign|1);
312 return e;
313 }
314
315 static AVExpr * parse_term(Parser *p){
316 AVExpr * e = parse_factor(p);
317 while(p->s[0]=='*' || p->s[0]=='/'){
318 int c= *p->s++;
319 e= new_eval_expr(c == '*' ? e_mul : e_div, 1, e, parse_factor(p));
320 if (!e)
321 return NULL;
322 }
323 return e;
324 }
325
326 static AVExpr * parse_subexpr(Parser *p) {
327 AVExpr * e = parse_term(p);
328 while(*p->s == '+' || *p->s == '-') {
329 e= new_eval_expr(e_add, 1, e, parse_term(p));
330 if (!e)
331 return NULL;
332 };
333
334 return e;
335 }
336
337 static AVExpr * parse_expr(Parser *p) {
338 AVExpr * e;
339
340 if(p->stack_index <= 0) //protect against stack overflows
341 return NULL;
342 p->stack_index--;
343
344 e = parse_subexpr(p);
345
346 while(*p->s == ';') {
347 p->s++;
348 e= new_eval_expr(e_last, 1, e, parse_subexpr(p));
349 if (!e)
350 return NULL;
351 };
352
353 p->stack_index++;
354
355 return e;
356 }
357
358 static int verify_expr(AVExpr * e) {
359 if (!e) return 0;
360 switch (e->type) {
361 case e_value:
362 case e_const: return 1;
363 case e_func0:
364 case e_func1:
365 case e_squish:
366 case e_ld:
367 case e_gauss: return verify_expr(e->param[0]);
368 default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
369 }
370 }
371
372 AVExpr *ff_parse_expr(const char *s,
373 const char * const *const_name,
374 const char * const *func1_name, double (* const *func1)(void *, double),
375 const char * const *func2_name, double (* const *func2)(void *, double, double),
376 const char **error){
377 Parser p;
378 AVExpr *e = NULL;
379 char *w = av_malloc(strlen(s) + 1);
380 char *wp = w;
381
382 if (!w)
383 goto end;
384
385 while (*s)
386 if (!isspace(*s++)) *wp++ = s[-1];
387 *wp++ = 0;
388
389 p.stack_index=100;
390 p.s= w;
391 p.const_name = const_name;
392 p.func1 = func1;
393 p.func1_name = func1_name;
394 p.func2 = func2;
395 p.func2_name = func2_name;
396 p.error= error;
397
398 e = parse_expr(&p);
399 if (!verify_expr(e)) {
400 ff_free_expr(e);
401 e = NULL;
402 }
403 end:
404 av_free(w);
405 return e;
406 }
407
408 double ff_eval_expr(AVExpr * e, const double *const_value, void *opaque) {
409 Parser p;
410
411 p.const_value= const_value;
412 p.opaque = opaque;
413 return eval_expr(&p, e);
414 }
415
416 double ff_parse_and_eval_expr(const char *s,
417 const char * const *const_name, const double *const_value,
418 const char * const *func1_name, double (* const *func1)(void *, double),
419 const char * const *func2_name, double (* const *func2)(void *, double, double),
420 void *opaque, const char **error){
421 AVExpr *e = ff_parse_expr(s, const_name, func1_name, func1, func2_name, func2, error);
422 double d;
423 if (!e) return NAN;
424 d = ff_eval_expr(e, const_value, opaque);
425 ff_free_expr(e);
426 return d;
427 }
428
429 #ifdef TEST
430 #undef printf
431 static double const_values[]={
432 M_PI,
433 M_E,
434 0
435 };
436 static const char *const_names[]={
437 "PI",
438 "E",
439 0
440 };
441 int main(void){
442 int i;
443 printf("%f == 12.7\n", ff_parse_and_eval_expr("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_names, const_values, NULL, NULL, NULL, NULL, NULL, NULL));
444 printf("%f == 0.931322575\n", ff_parse_and_eval_expr("80G/80Gi", const_names, const_values, NULL, NULL, NULL, NULL, NULL, NULL));
445
446 for(i=0; i<1050; i++){
447 START_TIMER
448 ff_parse_and_eval_expr("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_names, const_values, NULL, NULL, NULL, NULL, NULL, NULL);
449 STOP_TIMER("ff_parse_and_eval_expr")
450 }
451 return 0;
452 }
453 #endif