ffmpeg / libavcodec / eval.c @ e877eaac
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/*
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* simple arithmetic expression evaluator
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*
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* Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
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* Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file libavcodec/eval.c
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* simple arithmetic expression evaluator.
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*
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* see http://joe.hotchkiss.com/programming/eval/eval.html
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*/
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#include "avcodec.h" |
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#include "eval.h" |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <math.h> |
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#ifndef NAN
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#define NAN 0.0/0.0 |
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#endif
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#ifndef M_PI
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#define M_PI 3.14159265358979323846 |
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#endif
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typedef struct Parser{ |
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int stack_index;
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char *s;
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const double *const_value; |
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const char * const *const_name; // NULL terminated |
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double (**func1)(void *, double a); // NULL terminated |
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const char **func1_name; // NULL terminated |
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double (**func2)(void *, double a, double b); // NULL terminated |
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const char **func2_name; // NULL terminated |
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void *opaque;
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const char **error; |
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#define VARS 10 |
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double var[VARS];
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} Parser; |
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|
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static const int8_t si_prefixes['z' - 'E' + 1]={ |
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['y'-'E']= -24, |
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['z'-'E']= -21, |
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['a'-'E']= -18, |
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['f'-'E']= -15, |
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['p'-'E']= -12, |
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['n'-'E']= - 9, |
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['u'-'E']= - 6, |
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['m'-'E']= - 3, |
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['c'-'E']= - 2, |
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['d'-'E']= - 1, |
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['h'-'E']= 2, |
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['k'-'E']= 3, |
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['K'-'E']= 3, |
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['M'-'E']= 6, |
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['G'-'E']= 9, |
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['T'-'E']= 12, |
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['P'-'E']= 15, |
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['E'-'E']= 18, |
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['Z'-'E']= 21, |
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['Y'-'E']= 24, |
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}; |
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/** strtod() function extended with 'k', 'M', 'G', 'ki', 'Mi', 'Gi' and 'B'
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* postfixes. This allows using f.e. kB, MiB, G and B as a postfix. This
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* function assumes that the unit of numbers is bits not bytes.
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*/
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static double av_strtod(const char *numstr, char **tail) { |
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double d;
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char *next;
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d = strtod(numstr, &next); |
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/* if parsing succeeded, check for and interpret postfixes */
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if (next!=numstr) {
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|
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if(*next >= 'E' && *next <= 'z'){ |
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int e= si_prefixes[*next - 'E']; |
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if(e){
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if(next[1] == 'i'){ |
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d*= pow( 2, e/0.3); |
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next+=2;
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}else{
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d*= pow(10, e);
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next++; |
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} |
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} |
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} |
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if(*next=='B') { |
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d*=8;
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next++; |
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} |
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} |
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/* if requested, fill in tail with the position after the last parsed
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character */
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if (tail)
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*tail = next; |
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return d;
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} |
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static int strmatch(const char *s, const char *prefix){ |
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int i;
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for(i=0; prefix[i]; i++){ |
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if(prefix[i] != s[i]) return 0; |
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} |
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return 1; |
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} |
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struct ff_expr_s {
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enum {
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e_value, e_const, e_func0, e_func1, e_func2, |
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e_squish, e_gauss, e_ld, |
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e_mod, e_max, e_min, e_eq, e_gt, e_gte, |
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e_pow, e_mul, e_div, e_add, |
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e_last, e_st, e_while, |
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} type; |
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double value; // is sign in other types |
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union {
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int const_index;
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double (*func0)(double); |
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double (*func1)(void *, double); |
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double (*func2)(void *, double, double); |
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} a; |
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AVEvalExpr * param[2];
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}; |
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static double eval_expr(Parser * p, AVEvalExpr * e) { |
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switch (e->type) {
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case e_value: return e->value; |
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case e_const: return e->value * p->const_value[e->a.const_index]; |
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case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0])); |
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case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0])); |
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case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1])); |
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case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0]))); |
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case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); } |
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case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)]; |
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case e_while: {
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double d = NAN;
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while(eval_expr(p, e->param[0])) |
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d=eval_expr(p, e->param[1]);
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return d;
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} |
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default: {
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double d = eval_expr(p, e->param[0]); |
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double d2 = eval_expr(p, e->param[1]); |
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switch (e->type) {
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case e_mod: return e->value * (d - floor(d/d2)*d2); |
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case e_max: return e->value * (d > d2 ? d : d2); |
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case e_min: return e->value * (d < d2 ? d : d2); |
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case e_eq: return e->value * (d == d2 ? 1.0 : 0.0); |
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case e_gt: return e->value * (d > d2 ? 1.0 : 0.0); |
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case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0); |
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case e_pow: return e->value * pow(d, d2); |
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case e_mul: return e->value * (d * d2); |
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case e_div: return e->value * (d / d2); |
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case e_add: return e->value * (d + d2); |
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case e_last:return e->value * d2; |
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case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2); |
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} |
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} |
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} |
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return NAN;
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} |
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static AVEvalExpr * parse_expr(Parser *p);
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void ff_eval_free(AVEvalExpr * e) {
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if (!e) return; |
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ff_eval_free(e->param[0]);
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ff_eval_free(e->param[1]);
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av_freep(&e); |
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} |
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static AVEvalExpr * parse_primary(Parser *p) {
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AVEvalExpr * d = av_mallocz(sizeof(AVEvalExpr));
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char *next= p->s;
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int i;
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/* number */
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d->value = av_strtod(p->s, &next); |
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if(next != p->s){
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d->type = e_value; |
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p->s= next; |
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return d;
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} |
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d->value = 1;
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/* named constants */
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for(i=0; p->const_name && p->const_name[i]; i++){ |
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if(strmatch(p->s, p->const_name[i])){
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p->s+= strlen(p->const_name[i]); |
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d->type = e_const; |
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d->a.const_index = i; |
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return d;
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} |
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} |
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p->s= strchr(p->s, '(');
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if(p->s==NULL){ |
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*p->error = "undefined constant or missing (";
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p->s= next; |
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ff_eval_free(d); |
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return NULL; |
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} |
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p->s++; // "("
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if (*next == '(') { // special case do-nothing |
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av_freep(&d); |
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d = parse_expr(p); |
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if(p->s[0] != ')'){ |
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*p->error = "missing )";
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ff_eval_free(d); |
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return NULL; |
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} |
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p->s++; // ")"
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return d;
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} |
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d->param[0] = parse_expr(p);
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if(p->s[0]== ','){ |
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p->s++; // ","
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d->param[1] = parse_expr(p);
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} |
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if(p->s[0] != ')'){ |
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*p->error = "missing )";
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ff_eval_free(d); |
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return NULL; |
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} |
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p->s++; // ")"
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d->type = e_func0; |
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if( strmatch(next, "sinh" ) ) d->a.func0 = sinh; |
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else if( strmatch(next, "cosh" ) ) d->a.func0 = cosh; |
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else if( strmatch(next, "tanh" ) ) d->a.func0 = tanh; |
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else if( strmatch(next, "sin" ) ) d->a.func0 = sin; |
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else if( strmatch(next, "cos" ) ) d->a.func0 = cos; |
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else if( strmatch(next, "tan" ) ) d->a.func0 = tan; |
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else if( strmatch(next, "atan" ) ) d->a.func0 = atan; |
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else if( strmatch(next, "asin" ) ) d->a.func0 = asin; |
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else if( strmatch(next, "acos" ) ) d->a.func0 = acos; |
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else if( strmatch(next, "exp" ) ) d->a.func0 = exp; |
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else if( strmatch(next, "log" ) ) d->a.func0 = log; |
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else if( strmatch(next, "abs" ) ) d->a.func0 = fabs; |
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else if( strmatch(next, "squish") ) d->type = e_squish; |
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else if( strmatch(next, "gauss" ) ) d->type = e_gauss; |
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else if( strmatch(next, "mod" ) ) d->type = e_mod; |
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else if( strmatch(next, "max" ) ) d->type = e_max; |
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else if( strmatch(next, "min" ) ) d->type = e_min; |
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else if( strmatch(next, "eq" ) ) d->type = e_eq; |
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else if( strmatch(next, "gte" ) ) d->type = e_gte; |
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else if( strmatch(next, "gt" ) ) d->type = e_gt; |
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else if( strmatch(next, "lte" ) ) { AVEvalExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; } |
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else if( strmatch(next, "lt" ) ) { AVEvalExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; } |
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else if( strmatch(next, "ld" ) ) d->type = e_ld; |
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else if( strmatch(next, "st" ) ) d->type = e_st; |
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else if( strmatch(next, "while" ) ) d->type = e_while; |
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else {
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for(i=0; p->func1_name && p->func1_name[i]; i++){ |
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if(strmatch(next, p->func1_name[i])){
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d->a.func1 = p->func1[i]; |
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d->type = e_func1; |
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return d;
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} |
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} |
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for(i=0; p->func2_name && p->func2_name[i]; i++){ |
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if(strmatch(next, p->func2_name[i])){
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d->a.func2 = p->func2[i]; |
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d->type = e_func2; |
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return d;
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} |
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} |
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*p->error = "unknown function";
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ff_eval_free(d); |
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return NULL; |
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} |
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return d;
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} |
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static AVEvalExpr * new_eval_expr(int type, int value, AVEvalExpr *p0, AVEvalExpr *p1){ |
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AVEvalExpr * e = av_mallocz(sizeof(AVEvalExpr));
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e->type =type ; |
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e->value =value ; |
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e->param[0] =p0 ;
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e->param[1] =p1 ;
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return e;
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} |
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static AVEvalExpr * parse_pow(Parser *p, int *sign){ |
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*sign= (*p->s == '+') - (*p->s == '-'); |
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p->s += *sign&1;
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return parse_primary(p);
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} |
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static AVEvalExpr * parse_factor(Parser *p){
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int sign, sign2;
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AVEvalExpr * e = parse_pow(p, &sign); |
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while(p->s[0]=='^'){ |
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p->s++; |
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e= new_eval_expr(e_pow, 1, e, parse_pow(p, &sign2));
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if (e->param[1]) e->param[1]->value *= (sign2|1); |
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} |
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if (e) e->value *= (sign|1); |
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return e;
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} |
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|
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static AVEvalExpr * parse_term(Parser *p){
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AVEvalExpr * e = parse_factor(p); |
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while(p->s[0]=='*' || p->s[0]=='/'){ |
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int c= *p->s++;
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e= new_eval_expr(c == '*' ? e_mul : e_div, 1, e, parse_factor(p)); |
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} |
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return e;
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} |
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|
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static AVEvalExpr * parse_subexpr(Parser *p) {
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AVEvalExpr * e = parse_term(p); |
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while(*p->s == '+' || *p->s == '-') { |
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e= new_eval_expr(e_add, 1, e, parse_term(p));
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}; |
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return e;
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} |
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|
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static AVEvalExpr * parse_expr(Parser *p) {
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AVEvalExpr * e; |
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|
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if(p->stack_index <= 0) //protect against stack overflows |
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return NULL; |
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p->stack_index--; |
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|
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e = parse_subexpr(p); |
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|
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while(*p->s == ';') { |
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p->s++; |
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e= new_eval_expr(e_last, 1, e, parse_subexpr(p));
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}; |
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p->stack_index++; |
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return e;
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} |
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|
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static int verify_expr(AVEvalExpr * e) { |
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if (!e) return 0; |
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switch (e->type) {
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case e_value:
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case e_const: return 1; |
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case e_func0:
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case e_func1:
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case e_squish:
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case e_ld:
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case e_gauss: return verify_expr(e->param[0]); |
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default: return verify_expr(e->param[0]) && verify_expr(e->param[1]); |
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} |
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} |
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|
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AVEvalExpr * ff_parse(const char *s, const char * const *const_name, |
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double (**func1)(void *, double), const char **func1_name, |
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double (**func2)(void *, double, double), const char **func2_name, |
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const char **error){ |
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Parser p; |
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AVEvalExpr * e; |
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char w[strlen(s) + 1], * wp = w; |
| 385 |
|
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while (*s)
|
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if (!isspace(*s++)) *wp++ = s[-1]; |
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*wp++ = 0;
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|
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p.stack_index=100;
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p.s= w; |
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p.const_name = const_name; |
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p.func1 = func1; |
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p.func1_name = func1_name; |
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p.func2 = func2; |
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p.func2_name = func2_name; |
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p.error= error; |
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|
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e = parse_expr(&p); |
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if (!verify_expr(e)) {
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ff_eval_free(e); |
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return NULL; |
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} |
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return e;
|
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} |
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|
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double ff_parse_eval(AVEvalExpr * e, const double *const_value, void *opaque) { |
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Parser p; |
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p.const_value= const_value; |
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p.opaque = opaque; |
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return eval_expr(&p, e);
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} |
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|
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double ff_eval2(const char *s, const double *const_value, const char * const *const_name, |
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double (**func1)(void *, double), const char **func1_name, |
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double (**func2)(void *, double, double), const char **func2_name, |
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void *opaque, const char **error){ |
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AVEvalExpr * e = ff_parse(s, const_name, func1, func1_name, func2, func2_name, error); |
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double d;
|
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if (!e) return NAN; |
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d = ff_parse_eval(e, const_value, opaque); |
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ff_eval_free(e); |
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return d;
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} |
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|
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#ifdef TEST
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#undef printf
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static double const_values[]={ |
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M_PI, |
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M_E, |
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0
|
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}; |
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static const char *const_names[]={ |
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"PI",
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"E",
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0
|
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}; |
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int main(void){ |
| 440 |
int i;
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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)); |
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printf("%f == 0.931322575\n", ff_eval2("80G/80Gi", const_values, const_names, NULL, NULL, NULL, NULL, NULL, NULL)); |
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|
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for(i=0; i<1050; i++){ |
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START_TIMER |
| 446 |
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); |
| 447 |
STOP_TIMER("ff_eval2")
|
| 448 |
} |
| 449 |
return 0; |
| 450 |
} |
| 451 |
#endif
|