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"
37 typedef struct Parser {
41 const double *const_values;
42 const char * const *const_names; // NULL terminated
43 double (* const *funcs1)(void *, double a); // NULL terminated
44 const char * const *func1_names; // NULL terminated
45 double (* const *funcs2)(void *, double a, double b); // NULL terminated
46 const char * const *func2_names; // NULL terminated
54 static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };
56 static const int8_t si_prefixes['z' - 'E' + 1] = {
79 double av_strtod(const char *numstr, char **tail)
83 d = strtod(numstr, &next);
84 /* if parsing succeeded, check for and interpret postfixes */
86 if (next[0] == 'd' && next[1] == 'B') {
87 /* treat dB as decibels instead of decibytes */
90 } else if (*next >= 'E' && *next <= 'z') {
91 int e= si_prefixes[*next - 'E'];
108 /* if requested, fill in tail with the position after the last parsed
115 #define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')
117 static int strmatch(const char *s, const char *prefix)
120 for (i=0; prefix[i]; i++) {
121 if (prefix[i] != s[i]) return 0;
123 /* return 1 only if the s identifier is terminated */
124 return !IS_IDENTIFIER_CHAR(s[i]);
129 e_value, e_const, e_func0, e_func1, e_func2,
130 e_squish, e_gauss, e_ld, e_isnan, e_isinf,
131 e_mod, e_max, e_min, e_eq, e_gt, e_gte,
132 e_pow, e_mul, e_div, e_add,
133 e_last, e_st, e_while, e_floor, e_ceil, e_trunc,
136 double value; // is sign in other types
139 double (*func0)(double);
140 double (*func1)(void *, double);
141 double (*func2)(void *, double, double);
143 struct AVExpr *param[2];
146 static double eval_expr(Parser *p, AVExpr *e)
149 case e_value: return e->value;
150 case e_const: return e->value * p->const_values[e->a.const_index];
151 case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
152 case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
153 case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
154 case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
155 case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
156 case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
157 case e_isnan: return e->value * !!isnan(eval_expr(p, e->param[0]));
158 case e_isinf: return e->value * !!isinf(eval_expr(p, e->param[0]));
159 case e_floor: return e->value * floor(eval_expr(p, e->param[0]));
160 case e_ceil : return e->value * ceil (eval_expr(p, e->param[0]));
161 case e_trunc: return e->value * trunc(eval_expr(p, e->param[0]));
162 case e_sqrt: return e->value * sqrt (eval_expr(p, e->param[0]));
163 case e_not: return e->value * eval_expr(p, e->param[0]) == 0;
166 while (eval_expr(p, e->param[0]))
167 d=eval_expr(p, e->param[1]);
171 double d = eval_expr(p, e->param[0]);
172 double d2 = eval_expr(p, e->param[1]);
174 case e_mod: return e->value * (d - floor(d/d2)*d2);
175 case e_max: return e->value * (d > d2 ? d : d2);
176 case e_min: return e->value * (d < d2 ? d : d2);
177 case e_eq: return e->value * (d == d2 ? 1.0 : 0.0);
178 case e_gt: return e->value * (d > d2 ? 1.0 : 0.0);
179 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
180 case e_pow: return e->value * pow(d, d2);
181 case e_mul: return e->value * (d * d2);
182 case e_div: return e->value * (d / d2);
183 case e_add: return e->value * (d + d2);
184 case e_last:return e->value * d2;
185 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
192 static int parse_expr(AVExpr **e, Parser *p);
194 void av_expr_free(AVExpr *e)
197 av_expr_free(e->param[0]);
198 av_expr_free(e->param[1]);
202 static int parse_primary(AVExpr **e, Parser *p)
204 AVExpr *d = av_mallocz(sizeof(AVExpr));
205 char *next = p->s, *s0 = p->s;
209 return AVERROR(ENOMEM);
212 d->value = av_strtod(p->s, &next);
221 /* named constants */
222 for (i=0; p->const_names && p->const_names[i]; i++) {
223 if (strmatch(p->s, p->const_names[i])) {
224 p->s+= strlen(p->const_names[i]);
226 d->a.const_index = i;
232 p->s= strchr(p->s, '(');
234 av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
237 return AVERROR(EINVAL);
240 if (*next == '(') { // special case do-nothing
242 if ((ret = parse_expr(&d, p)) < 0)
244 if (p->s[0] != ')') {
245 av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
247 return AVERROR(EINVAL);
253 if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
259 parse_expr(&d->param[1], p);
261 if (p->s[0] != ')') {
262 av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
264 return AVERROR(EINVAL);
269 if (strmatch(next, "sinh" )) d->a.func0 = sinh;
270 else if (strmatch(next, "cosh" )) d->a.func0 = cosh;
271 else if (strmatch(next, "tanh" )) d->a.func0 = tanh;
272 else if (strmatch(next, "sin" )) d->a.func0 = sin;
273 else if (strmatch(next, "cos" )) d->a.func0 = cos;
274 else if (strmatch(next, "tan" )) d->a.func0 = tan;
275 else if (strmatch(next, "atan" )) d->a.func0 = atan;
276 else if (strmatch(next, "asin" )) d->a.func0 = asin;
277 else if (strmatch(next, "acos" )) d->a.func0 = acos;
278 else if (strmatch(next, "exp" )) d->a.func0 = exp;
279 else if (strmatch(next, "log" )) d->a.func0 = log;
280 else if (strmatch(next, "abs" )) d->a.func0 = fabs;
281 else if (strmatch(next, "squish")) d->type = e_squish;
282 else if (strmatch(next, "gauss" )) d->type = e_gauss;
283 else if (strmatch(next, "mod" )) d->type = e_mod;
284 else if (strmatch(next, "max" )) d->type = e_max;
285 else if (strmatch(next, "min" )) d->type = e_min;
286 else if (strmatch(next, "eq" )) d->type = e_eq;
287 else if (strmatch(next, "gte" )) d->type = e_gte;
288 else if (strmatch(next, "gt" )) d->type = e_gt;
289 else if (strmatch(next, "lte" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
290 else if (strmatch(next, "lt" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
291 else if (strmatch(next, "ld" )) d->type = e_ld;
292 else if (strmatch(next, "isnan" )) d->type = e_isnan;
293 else if (strmatch(next, "isinf" )) d->type = e_isinf;
294 else if (strmatch(next, "st" )) d->type = e_st;
295 else if (strmatch(next, "while" )) d->type = e_while;
296 else if (strmatch(next, "floor" )) d->type = e_floor;
297 else if (strmatch(next, "ceil" )) d->type = e_ceil;
298 else if (strmatch(next, "trunc" )) d->type = e_trunc;
299 else if (strmatch(next, "sqrt" )) d->type = e_sqrt;
300 else if (strmatch(next, "not" )) d->type = e_not;
302 for (i=0; p->func1_names && p->func1_names[i]; i++) {
303 if (strmatch(next, p->func1_names[i])) {
304 d->a.func1 = p->funcs1[i];
311 for (i=0; p->func2_names && p->func2_names[i]; i++) {
312 if (strmatch(next, p->func2_names[i])) {
313 d->a.func2 = p->funcs2[i];
320 av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
322 return AVERROR(EINVAL);
329 static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
331 AVExpr *e = av_mallocz(sizeof(AVExpr));
341 static int parse_pow(AVExpr **e, Parser *p, int *sign)
343 *sign= (*p->s == '+') - (*p->s == '-');
345 return parse_primary(e, p);
348 static int parse_dB(AVExpr **e, Parser *p, int *sign)
350 /* do not filter out the negative sign when parsing a dB value.
351 for example, -3dB is not the same as -(3dB) */
354 double av_unused ignored = strtod(p->s, &next);
355 if (next != p->s && next[0] == 'd' && next[1] == 'B') {
357 return parse_primary(e, p);
360 return parse_pow(e, p, sign);
363 static int parse_factor(AVExpr **e, Parser *p)
365 int sign, sign2, ret;
366 AVExpr *e0, *e1, *e2;
367 if ((ret = parse_dB(&e0, p, &sign)) < 0)
372 if ((ret = parse_dB(&e2, p, &sign2)) < 0) {
376 e0 = new_eval_expr(e_pow, 1, e1, e2);
380 return AVERROR(ENOMEM);
382 if (e0->param[1]) e0->param[1]->value *= (sign2|1);
384 if (e0) e0->value *= (sign|1);
390 static int parse_term(AVExpr **e, Parser *p)
393 AVExpr *e0, *e1, *e2;
394 if ((ret = parse_factor(&e0, p)) < 0)
396 while (p->s[0]=='*' || p->s[0]=='/') {
399 if ((ret = parse_factor(&e2, p)) < 0) {
403 e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
407 return AVERROR(ENOMEM);
414 static int parse_subexpr(AVExpr **e, Parser *p)
417 AVExpr *e0, *e1, *e2;
418 if ((ret = parse_term(&e0, p)) < 0)
420 while (*p->s == '+' || *p->s == '-') {
422 if ((ret = parse_term(&e2, p)) < 0) {
426 e0 = new_eval_expr(e_add, 1, e1, e2);
430 return AVERROR(ENOMEM);
438 static int parse_expr(AVExpr **e, Parser *p)
441 AVExpr *e0, *e1, *e2;
442 if (p->stack_index <= 0) //protect against stack overflows
443 return AVERROR(EINVAL);
446 if ((ret = parse_subexpr(&e0, p)) < 0)
448 while (*p->s == ';') {
451 if ((ret = parse_subexpr(&e2, p)) < 0) {
455 e0 = new_eval_expr(e_last, 1, e1, e2);
459 return AVERROR(ENOMEM);
468 static int verify_expr(AVExpr *e)
473 case e_const: return 1;
486 return verify_expr(e->param[0]);
487 default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
491 int av_expr_parse(AVExpr **expr, const char *s,
492 const char * const *const_names,
493 const char * const *func1_names, double (* const *funcs1)(void *, double),
494 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
495 int log_offset, void *log_ctx)
499 char *w = av_malloc(strlen(s) + 1);
505 return AVERROR(ENOMEM);
508 if (!av_isspace(*s++)) *wp++ = s[-1];
514 p.const_names = const_names;
516 p.func1_names = func1_names;
518 p.func2_names = func2_names;
519 p.log_offset = log_offset;
522 if ((ret = parse_expr(&e, &p)) < 0)
526 av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
527 ret = AVERROR(EINVAL);
530 if (!verify_expr(e)) {
532 ret = AVERROR(EINVAL);
541 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
545 p.const_values = const_values;
547 return eval_expr(&p, e);
550 int av_expr_parse_and_eval(double *d, const char *s,
551 const char * const *const_names, const double *const_values,
552 const char * const *func1_names, double (* const *funcs1)(void *, double),
553 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
554 void *opaque, int log_offset, void *log_ctx)
557 int ret = av_expr_parse(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
563 *d = av_expr_eval(e, const_values, opaque);
565 return isnan(*d) ? AVERROR(EINVAL) : 0;
571 static const double const_values[] = {
577 static const char *const const_names[] = {
583 int main(int argc, char **argv)
587 const char *const *expr;
588 static const char *const exprs[] = {
594 "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
615 "bar + PI + E + 100f*2 + foo",
616 "13k + 12f - foo(1, 2)",
629 /* compute 1+2+...+N */
630 "st(0, 1); while(lte(ld(0), 100), st(1, ld(1)+ld(0));st(0, ld(0)+1)); ld(1)",
632 "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)",
634 "st(0, 1); while(lte(ld(0),100), st(1, ld(1)+ld(0)); st(0, ld(0)+1))",
658 for (expr = exprs; *expr; expr++) {
659 printf("Evaluating '%s'\n", *expr);
660 av_expr_parse_and_eval(&d, *expr,
661 const_names, const_values,
662 NULL, NULL, NULL, NULL, NULL, 0, NULL);
664 printf("'%s' -> nan\n\n", *expr);
666 printf("'%s' -> %f\n\n", *expr, d);
669 av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
670 const_names, const_values,
671 NULL, NULL, NULL, NULL, NULL, 0, NULL);
672 printf("%f == 12.7\n", d);
673 av_expr_parse_and_eval(&d, "80G/80Gi",
674 const_names, const_values,
675 NULL, NULL, NULL, NULL, NULL, 0, NULL);
676 printf("%f == 0.931322575\n", d);
678 if (argc > 1 && !strcmp(argv[1], "-t")) {
679 for (i = 0; i < 1050; i++) {
681 av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
682 const_names, const_values,
683 NULL, NULL, NULL, NULL, NULL, 0, NULL);
684 STOP_TIMER("av_expr_parse_and_eval");