c1bb42d6acdf7725d86d320a0d5d51e3a41bd4a2
[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_value;
37 const char * const *const_name; // NULL terminated
38 double (* const *func1)(void *, double a); // NULL terminated
39 const char * const *func1_name; // NULL terminated
40 double (* const *func2)(void *, double a, double b); // NULL terminated
41 const char * const *func2_name; // 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 double d;
76 char *next;
77 d = strtod(numstr, &next);
78 /* if parsing succeeded, check for and interpret postfixes */
79 if (next!=numstr) {
80
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 int i;
108 for(i=0; prefix[i]; i++){
109 if(prefix[i] != s[i]) return 0;
110 }
111 return 1;
112 }
113
114 struct AVExpr {
115 enum {
116 e_value, e_const, e_func0, e_func1, e_func2,
117 e_squish, e_gauss, e_ld,
118 e_mod, e_max, e_min, e_eq, e_gt, e_gte,
119 e_pow, e_mul, e_div, e_add,
120 e_last, e_st, e_while,
121 } type;
122 double value; // is sign in other types
123 union {
124 int const_index;
125 double (*func0)(double);
126 double (*func1)(void *, double);
127 double (*func2)(void *, double, double);
128 } a;
129 struct AVExpr *param[2];
130 };
131
132 static double eval_expr(Parser * p, AVExpr * e) {
133 switch (e->type) {
134 case e_value: return e->value;
135 case e_const: return e->value * p->const_value[e->a.const_index];
136 case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
137 case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
138 case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
139 case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
140 case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
141 case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
142 case e_while: {
143 double d = NAN;
144 while(eval_expr(p, e->param[0]))
145 d=eval_expr(p, e->param[1]);
146 return d;
147 }
148 default: {
149 double d = eval_expr(p, e->param[0]);
150 double d2 = eval_expr(p, e->param[1]);
151 switch (e->type) {
152 case e_mod: return e->value * (d - floor(d/d2)*d2);
153 case e_max: return e->value * (d > d2 ? d : d2);
154 case e_min: return e->value * (d < d2 ? d : d2);
155 case e_eq: return e->value * (d == d2 ? 1.0 : 0.0);
156 case e_gt: return e->value * (d > d2 ? 1.0 : 0.0);
157 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
158 case e_pow: return e->value * pow(d, d2);
159 case e_mul: return e->value * (d * d2);
160 case e_div: return e->value * (d / d2);
161 case e_add: return e->value * (d + d2);
162 case e_last:return e->value * d2;
163 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
164 }
165 }
166 }
167 return NAN;
168 }
169
170 static AVExpr * parse_expr(Parser *p);
171
172 void ff_free_expr(AVExpr * e) {
173 if (!e) return;
174 ff_free_expr(e->param[0]);
175 ff_free_expr(e->param[1]);
176 av_freep(&e);
177 }
178
179 static AVExpr * parse_primary(Parser *p) {
180 AVExpr * d = av_mallocz(sizeof(AVExpr));
181 char *next= p->s;
182 int i;
183
184 if (!d)
185 return NULL;
186
187 /* number */
188 d->value = av_strtod(p->s, &next);
189 if(next != p->s){
190 d->type = e_value;
191 p->s= next;
192 return d;
193 }
194 d->value = 1;
195
196 /* named constants */
197 for(i=0; p->const_name && p->const_name[i]; i++){
198 if(strmatch(p->s, p->const_name[i])){
199 p->s+= strlen(p->const_name[i]);
200 d->type = e_const;
201 d->a.const_index = i;
202 return d;
203 }
204 }
205
206 p->s= strchr(p->s, '(');
207 if(p->s==NULL){
208 av_log(p, AV_LOG_ERROR, "undefined constant or missing (\n");
209 p->s= next;
210 ff_free_expr(d);
211 return NULL;
212 }
213 p->s++; // "("
214 if (*next == '(') { // special case do-nothing
215 av_freep(&d);
216 d = parse_expr(p);
217 if(p->s[0] != ')'){
218 av_log(p, AV_LOG_ERROR, "missing )\n");
219 ff_free_expr(d);
220 return NULL;
221 }
222 p->s++; // ")"
223 return d;
224 }
225 d->param[0] = parse_expr(p);
226 if(p->s[0]== ','){
227 p->s++; // ","
228 d->param[1] = parse_expr(p);
229 }
230 if(p->s[0] != ')'){
231 av_log(p, AV_LOG_ERROR, "missing )\n");
232 ff_free_expr(d);
233 return NULL;
234 }
235 p->s++; // ")"
236
237 d->type = e_func0;
238 if( strmatch(next, "sinh" ) ) d->a.func0 = sinh;
239 else if( strmatch(next, "cosh" ) ) d->a.func0 = cosh;
240 else if( strmatch(next, "tanh" ) ) d->a.func0 = tanh;
241 else if( strmatch(next, "sin" ) ) d->a.func0 = sin;
242 else if( strmatch(next, "cos" ) ) d->a.func0 = cos;
243 else if( strmatch(next, "tan" ) ) d->a.func0 = tan;
244 else if( strmatch(next, "atan" ) ) d->a.func0 = atan;
245 else if( strmatch(next, "asin" ) ) d->a.func0 = asin;
246 else if( strmatch(next, "acos" ) ) d->a.func0 = acos;
247 else if( strmatch(next, "exp" ) ) d->a.func0 = exp;
248 else if( strmatch(next, "log" ) ) d->a.func0 = log;
249 else if( strmatch(next, "abs" ) ) d->a.func0 = fabs;
250 else if( strmatch(next, "squish") ) d->type = e_squish;
251 else if( strmatch(next, "gauss" ) ) d->type = e_gauss;
252 else if( strmatch(next, "mod" ) ) d->type = e_mod;
253 else if( strmatch(next, "max" ) ) d->type = e_max;
254 else if( strmatch(next, "min" ) ) d->type = e_min;
255 else if( strmatch(next, "eq" ) ) d->type = e_eq;
256 else if( strmatch(next, "gte" ) ) d->type = e_gte;
257 else if( strmatch(next, "gt" ) ) d->type = e_gt;
258 else if( strmatch(next, "lte" ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
259 else if( strmatch(next, "lt" ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
260 else if( strmatch(next, "ld" ) ) d->type = e_ld;
261 else if( strmatch(next, "st" ) ) d->type = e_st;
262 else if( strmatch(next, "while" ) ) d->type = e_while;
263 else {
264 for(i=0; p->func1_name && p->func1_name[i]; i++){
265 if(strmatch(next, p->func1_name[i])){
266 d->a.func1 = p->func1[i];
267 d->type = e_func1;
268 return d;
269 }
270 }
271
272 for(i=0; p->func2_name && p->func2_name[i]; i++){
273 if(strmatch(next, p->func2_name[i])){
274 d->a.func2 = p->func2[i];
275 d->type = e_func2;
276 return d;
277 }
278 }
279
280 av_log(p, AV_LOG_ERROR, "unknown function\n");
281 ff_free_expr(d);
282 return NULL;
283 }
284
285 return d;
286 }
287
288 static AVExpr * new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1){
289 AVExpr * e = av_mallocz(sizeof(AVExpr));
290 if (!e)
291 return NULL;
292 e->type =type ;
293 e->value =value ;
294 e->param[0] =p0 ;
295 e->param[1] =p1 ;
296 return e;
297 }
298
299 static AVExpr * parse_pow(Parser *p, int *sign){
300 *sign= (*p->s == '+') - (*p->s == '-');
301 p->s += *sign&1;
302 return parse_primary(p);
303 }
304
305 static AVExpr * parse_factor(Parser *p){
306 int sign, sign2;
307 AVExpr * e = parse_pow(p, &sign);
308 while(p->s[0]=='^'){
309 p->s++;
310 e= new_eval_expr(e_pow, 1, e, parse_pow(p, &sign2));
311 if (!e)
312 return NULL;
313 if (e->param[1]) e->param[1]->value *= (sign2|1);
314 }
315 if (e) e->value *= (sign|1);
316 return e;
317 }
318
319 static AVExpr * parse_term(Parser *p){
320 AVExpr * e = parse_factor(p);
321 while(p->s[0]=='*' || p->s[0]=='/'){
322 int c= *p->s++;
323 e= new_eval_expr(c == '*' ? e_mul : e_div, 1, e, parse_factor(p));
324 if (!e)
325 return NULL;
326 }
327 return e;
328 }
329
330 static AVExpr * parse_subexpr(Parser *p) {
331 AVExpr * e = parse_term(p);
332 while(*p->s == '+' || *p->s == '-') {
333 e= new_eval_expr(e_add, 1, e, parse_term(p));
334 if (!e)
335 return NULL;
336 };
337
338 return e;
339 }
340
341 static AVExpr * parse_expr(Parser *p) {
342 AVExpr * e;
343
344 if(p->stack_index <= 0) //protect against stack overflows
345 return NULL;
346 p->stack_index--;
347
348 e = parse_subexpr(p);
349
350 while(*p->s == ';') {
351 p->s++;
352 e= new_eval_expr(e_last, 1, e, parse_subexpr(p));
353 if (!e)
354 return NULL;
355 };
356
357 p->stack_index++;
358
359 return e;
360 }
361
362 static int verify_expr(AVExpr * e) {
363 if (!e) return 0;
364 switch (e->type) {
365 case e_value:
366 case e_const: return 1;
367 case e_func0:
368 case e_func1:
369 case e_squish:
370 case e_ld:
371 case e_gauss: return verify_expr(e->param[0]);
372 default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
373 }
374 }
375
376 AVExpr *ff_parse_expr(const char *s,
377 const char * const *const_name,
378 const char * const *func1_name, double (* const *func1)(void *, double),
379 const char * const *func2_name, double (* const *func2)(void *, double, double),
380 int log_offset, void *log_ctx)
381 {
382 Parser p;
383 AVExpr *e = NULL;
384 char *w = av_malloc(strlen(s) + 1);
385 char *wp = w;
386
387 if (!w)
388 goto end;
389
390 while (*s)
391 if (!isspace(*s++)) *wp++ = s[-1];
392 *wp++ = 0;
393
394 p.class = &class;
395 p.stack_index=100;
396 p.s= w;
397 p.const_name = const_name;
398 p.func1 = func1;
399 p.func1_name = func1_name;
400 p.func2 = func2;
401 p.func2_name = func2_name;
402 p.log_offset = log_offset;
403 p.log_ctx = log_ctx;
404
405 e = parse_expr(&p);
406 if (!verify_expr(e)) {
407 ff_free_expr(e);
408 e = NULL;
409 }
410 end:
411 av_free(w);
412 return e;
413 }
414
415 double ff_eval_expr(AVExpr * 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_parse_and_eval_expr(const char *s,
424 const char * const *const_name, const double *const_value,
425 const char * const *func1_name, double (* const *func1)(void *, double),
426 const char * const *func2_name, double (* const *func2)(void *, double, double),
427 void *opaque, int log_offset, void *log_ctx)
428 {
429 AVExpr *e = ff_parse_expr(s, const_name, func1_name, func1, func2_name, func2, log_offset, log_ctx);
430 double d;
431 if (!e) return NAN;
432 d = ff_eval_expr(e, const_value, opaque);
433 ff_free_expr(e);
434 return d;
435 }
436
437 #ifdef TEST
438 #undef printf
439 static double const_values[]={
440 M_PI,
441 M_E,
442 0
443 };
444 static const char *const_names[]={
445 "PI",
446 "E",
447 0
448 };
449 int main(void){
450 int i;
451 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, 0, NULL));
452 printf("%f == 0.931322575\n", ff_parse_and_eval_expr("80G/80Gi", const_names, const_values, NULL, NULL, NULL, NULL, NULL, NULL));
453
454 for(i=0; i<1050; i++){
455 START_TIMER
456 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, 0, NULL);
457 STOP_TIMER("ff_parse_and_eval_expr")
458 }
459 return 0;
460 }
461 #endif