2 * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
3 * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
5 * This file is part of Libav.
7 * Libav 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.
12 * Libav 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.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * simple arithmetic expression evaluator.
26 * see http://joe.hotchkiss.com/programming/eval/eval.html
29 #include "attributes.h"
34 #include "mathematics.h"
38 typedef struct Parser {
42 const double *const_values;
43 const char * const *const_names; // NULL terminated
44 double (* const *funcs1)(void *, double a); // NULL terminated
45 const char * const *func1_names; // NULL terminated
46 double (* const *funcs2)(void *, double a, double b); // NULL terminated
47 const char * const *func2_names; // NULL terminated
55 static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };
57 static const int8_t si_prefixes['z' - 'E' + 1] = {
80 double av_strtod(const char *numstr, char **tail)
84 d = strtod(numstr, &next);
85 /* if parsing succeeded, check for and interpret postfixes */
87 if (next[0] == 'd' && next[1] == 'B') {
88 /* treat dB as decibels instead of decibytes */
91 } else if (*next >= 'E' && *next <= 'z') {
92 int e= si_prefixes[*next - 'E'];
109 /* if requested, fill in tail with the position after the last parsed
116 #define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')
118 static int strmatch(const char *s, const char *prefix)
121 for (i=0; prefix[i]; i++) {
122 if (prefix[i] != s[i]) return 0;
124 /* return 1 only if the s identifier is terminated */
125 return !IS_IDENTIFIER_CHAR(s[i]);
130 e_value, e_const, e_func0, e_func1, e_func2,
131 e_squish, e_gauss, e_ld, e_isnan, e_isinf,
132 e_mod, e_max, e_min, e_eq, e_gt, e_gte,
133 e_pow, e_mul, e_div, e_add,
134 e_last, e_st, e_while, e_floor, e_ceil, e_trunc,
137 double value; // is sign in other types
140 double (*func0)(double);
141 double (*func1)(void *, double);
142 double (*func2)(void *, double, double);
144 struct AVExpr *param[2];
147 static double eval_expr(Parser *p, AVExpr *e)
150 case e_value: return e->value;
151 case e_const: return e->value * p->const_values[e->a.const_index];
152 case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
153 case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
154 case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
155 case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
156 case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
157 case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
158 case e_isnan: return e->value * !!isnan(eval_expr(p, e->param[0]));
159 case e_isinf: return e->value * !!isinf(eval_expr(p, e->param[0]));
160 case e_floor: return e->value * floor(eval_expr(p, e->param[0]));
161 case e_ceil : return e->value * ceil (eval_expr(p, e->param[0]));
162 case e_trunc: return e->value * trunc(eval_expr(p, e->param[0]));
163 case e_sqrt: return e->value * sqrt (eval_expr(p, e->param[0]));
164 case e_not: return e->value * eval_expr(p, e->param[0]) == 0;
167 while (eval_expr(p, e->param[0]))
168 d=eval_expr(p, e->param[1]);
172 double d = eval_expr(p, e->param[0]);
173 double d2 = eval_expr(p, e->param[1]);
175 case e_mod: return e->value * (d - floor(d/d2)*d2);
176 case e_max: return e->value * (d > d2 ? d : d2);
177 case e_min: return e->value * (d < d2 ? d : d2);
178 case e_eq: return e->value * (d == d2 ? 1.0 : 0.0);
179 case e_gt: return e->value * (d > d2 ? 1.0 : 0.0);
180 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
181 case e_pow: return e->value * pow(d, d2);
182 case e_mul: return e->value * (d * d2);
183 case e_div: return e->value * (d / d2);
184 case e_add: return e->value * (d + d2);
185 case e_last:return e->value * d2;
186 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
193 static int parse_expr(AVExpr **e, Parser *p);
195 void av_expr_free(AVExpr *e)
198 av_expr_free(e->param[0]);
199 av_expr_free(e->param[1]);
203 static int parse_primary(AVExpr **e, Parser *p)
205 AVExpr *d = av_mallocz(sizeof(AVExpr));
206 char *next = p->s, *s0 = p->s;
210 return AVERROR(ENOMEM);
213 d->value = av_strtod(p->s, &next);
222 /* named constants */
223 for (i=0; p->const_names && p->const_names[i]; i++) {
224 if (strmatch(p->s, p->const_names[i])) {
225 p->s+= strlen(p->const_names[i]);
227 d->a.const_index = i;
233 p->s= strchr(p->s, '(');
235 av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
238 return AVERROR(EINVAL);
241 if (*next == '(') { // special case do-nothing
243 if ((ret = parse_expr(&d, p)) < 0)
245 if (p->s[0] != ')') {
246 av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
248 return AVERROR(EINVAL);
254 if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
260 parse_expr(&d->param[1], p);
262 if (p->s[0] != ')') {
263 av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
265 return AVERROR(EINVAL);
270 if (strmatch(next, "sinh" )) d->a.func0 = sinh;
271 else if (strmatch(next, "cosh" )) d->a.func0 = cosh;
272 else if (strmatch(next, "tanh" )) d->a.func0 = tanh;
273 else if (strmatch(next, "sin" )) d->a.func0 = sin;
274 else if (strmatch(next, "cos" )) d->a.func0 = cos;
275 else if (strmatch(next, "tan" )) d->a.func0 = tan;
276 else if (strmatch(next, "atan" )) d->a.func0 = atan;
277 else if (strmatch(next, "asin" )) d->a.func0 = asin;
278 else if (strmatch(next, "acos" )) d->a.func0 = acos;
279 else if (strmatch(next, "exp" )) d->a.func0 = exp;
280 else if (strmatch(next, "log" )) d->a.func0 = log;
281 else if (strmatch(next, "abs" )) d->a.func0 = fabs;
282 else if (strmatch(next, "squish")) d->type = e_squish;
283 else if (strmatch(next, "gauss" )) d->type = e_gauss;
284 else if (strmatch(next, "mod" )) d->type = e_mod;
285 else if (strmatch(next, "max" )) d->type = e_max;
286 else if (strmatch(next, "min" )) d->type = e_min;
287 else if (strmatch(next, "eq" )) d->type = e_eq;
288 else if (strmatch(next, "gte" )) d->type = e_gte;
289 else if (strmatch(next, "gt" )) d->type = e_gt;
290 else if (strmatch(next, "lte" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
291 else if (strmatch(next, "lt" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
292 else if (strmatch(next, "ld" )) d->type = e_ld;
293 else if (strmatch(next, "isnan" )) d->type = e_isnan;
294 else if (strmatch(next, "isinf" )) d->type = e_isinf;
295 else if (strmatch(next, "st" )) d->type = e_st;
296 else if (strmatch(next, "while" )) d->type = e_while;
297 else if (strmatch(next, "floor" )) d->type = e_floor;
298 else if (strmatch(next, "ceil" )) d->type = e_ceil;
299 else if (strmatch(next, "trunc" )) d->type = e_trunc;
300 else if (strmatch(next, "sqrt" )) d->type = e_sqrt;
301 else if (strmatch(next, "not" )) d->type = e_not;
303 for (i=0; p->func1_names && p->func1_names[i]; i++) {
304 if (strmatch(next, p->func1_names[i])) {
305 d->a.func1 = p->funcs1[i];
312 for (i=0; p->func2_names && p->func2_names[i]; i++) {
313 if (strmatch(next, p->func2_names[i])) {
314 d->a.func2 = p->funcs2[i];
321 av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
323 return AVERROR(EINVAL);
330 static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
332 AVExpr *e = av_mallocz(sizeof(AVExpr));
342 static int parse_pow(AVExpr **e, Parser *p, int *sign)
344 *sign= (*p->s == '+') - (*p->s == '-');
346 return parse_primary(e, p);
349 static int parse_dB(AVExpr **e, Parser *p, int *sign)
351 /* do not filter out the negative sign when parsing a dB value.
352 for example, -3dB is not the same as -(3dB) */
355 double av_unused ignored = strtod(p->s, &next);
356 if (next != p->s && next[0] == 'd' && next[1] == 'B') {
358 return parse_primary(e, p);
361 return parse_pow(e, p, sign);
364 static int parse_factor(AVExpr **e, Parser *p)
366 int sign, sign2, ret;
367 AVExpr *e0, *e1, *e2;
368 if ((ret = parse_dB(&e0, p, &sign)) < 0)
373 if ((ret = parse_dB(&e2, p, &sign2)) < 0) {
377 e0 = new_eval_expr(e_pow, 1, e1, e2);
381 return AVERROR(ENOMEM);
383 if (e0->param[1]) e0->param[1]->value *= (sign2|1);
385 if (e0) e0->value *= (sign|1);
391 static int parse_term(AVExpr **e, Parser *p)
394 AVExpr *e0, *e1, *e2;
395 if ((ret = parse_factor(&e0, p)) < 0)
397 while (p->s[0]=='*' || p->s[0]=='/') {
400 if ((ret = parse_factor(&e2, p)) < 0) {
404 e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
408 return AVERROR(ENOMEM);
415 static int parse_subexpr(AVExpr **e, Parser *p)
418 AVExpr *e0, *e1, *e2;
419 if ((ret = parse_term(&e0, p)) < 0)
421 while (*p->s == '+' || *p->s == '-') {
423 if ((ret = parse_term(&e2, p)) < 0) {
427 e0 = new_eval_expr(e_add, 1, e1, e2);
431 return AVERROR(ENOMEM);
439 static int parse_expr(AVExpr **e, Parser *p)
442 AVExpr *e0, *e1, *e2;
443 if (p->stack_index <= 0) //protect against stack overflows
444 return AVERROR(EINVAL);
447 if ((ret = parse_subexpr(&e0, p)) < 0)
449 while (*p->s == ';') {
452 if ((ret = parse_subexpr(&e2, p)) < 0) {
456 e0 = new_eval_expr(e_last, 1, e1, e2);
460 return AVERROR(ENOMEM);
469 static int verify_expr(AVExpr *e)
474 case e_const: return 1;
487 return verify_expr(e->param[0]);
488 default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
492 int av_expr_parse(AVExpr **expr, const char *s,
493 const char * const *const_names,
494 const char * const *func1_names, double (* const *funcs1)(void *, double),
495 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
496 int log_offset, void *log_ctx)
500 char *w = av_malloc(strlen(s) + 1);
506 return AVERROR(ENOMEM);
509 if (!av_isspace(*s++)) *wp++ = s[-1];
515 p.const_names = const_names;
517 p.func1_names = func1_names;
519 p.func2_names = func2_names;
520 p.log_offset = log_offset;
523 if ((ret = parse_expr(&e, &p)) < 0)
527 av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
528 ret = AVERROR(EINVAL);
531 if (!verify_expr(e)) {
533 ret = AVERROR(EINVAL);
542 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
546 p.const_values = const_values;
548 return eval_expr(&p, e);
551 int av_expr_parse_and_eval(double *d, const char *s,
552 const char * const *const_names, const double *const_values,
553 const char * const *func1_names, double (* const *funcs1)(void *, double),
554 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
555 void *opaque, int log_offset, void *log_ctx)
558 int ret = av_expr_parse(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
564 *d = av_expr_eval(e, const_values, opaque);
566 return isnan(*d) ? AVERROR(EINVAL) : 0;
572 static const double const_values[] = {
578 static const char *const const_names[] = {
584 int main(int argc, char **argv)
588 const char *const *expr;
589 static const char *const exprs[] = {
595 "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
616 "bar + PI + E + 100f*2 + foo",
617 "13k + 12f - foo(1, 2)",
630 /* compute 1+2+...+N */
631 "st(0, 1); while(lte(ld(0), 100), st(1, ld(1)+ld(0));st(0, ld(0)+1)); ld(1)",
633 "st(1, 1); st(2, 2); st(0, 1); while(lte(ld(0),10), st(3, ld(1)+ld(2)); st(1, ld(2)); st(2, ld(3)); st(0, ld(0)+1)); ld(3)",
635 "st(0, 1); while(lte(ld(0),100), st(1, ld(1)+ld(0)); st(0, ld(0)+1))",
659 for (expr = exprs; *expr; expr++) {
660 printf("Evaluating '%s'\n", *expr);
661 av_expr_parse_and_eval(&d, *expr,
662 const_names, const_values,
663 NULL, NULL, NULL, NULL, NULL, 0, NULL);
665 printf("'%s' -> nan\n\n", *expr);
667 printf("'%s' -> %f\n\n", *expr, d);
670 av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
671 const_names, const_values,
672 NULL, NULL, NULL, NULL, NULL, 0, NULL);
673 printf("%f == 12.7\n", d);
674 av_expr_parse_and_eval(&d, "80G/80Gi",
675 const_names, const_values,
676 NULL, NULL, NULL, NULL, NULL, 0, NULL);
677 printf("%f == 0.931322575\n", d);
679 if (argc > 1 && !strcmp(argv[1], "-t")) {
680 for (i = 0; i < 1050; i++) {
682 av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
683 const_names, const_values,
684 NULL, NULL, NULL, NULL, NULL, 0, NULL);
685 STOP_TIMER("av_expr_parse_and_eval");