mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-11-21 10:55:51 +02:00
250 lines
6.3 KiB
C
250 lines
6.3 KiB
C
/*
|
|
* simple arithmetic expression evaluator
|
|
*
|
|
* Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
|
|
*
|
|
* This library is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2 of the License, or (at your option) any later version.
|
|
*
|
|
* This library is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with this library; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*
|
|
*/
|
|
|
|
/*
|
|
* see http://joe.hotchkiss.com/programming/eval/eval.html
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <math.h>
|
|
|
|
#ifndef NAN
|
|
#define NAN 0
|
|
#endif
|
|
|
|
#ifndef M_PI
|
|
#define M_PI 3.14159265358979323846
|
|
#endif
|
|
|
|
#define STACK_SIZE 100
|
|
|
|
typedef struct Parser{
|
|
double stack[STACK_SIZE];
|
|
int stack_index;
|
|
char *s;
|
|
double *const_value;
|
|
char **const_name; // NULL terminated
|
|
double (**func1)(void *, double a); // NULL terminated
|
|
char **func1_name; // NULL terminated
|
|
double (**func2)(void *, double a, double b); // NULL terminated
|
|
char **func2_name; // NULL terminated
|
|
void *opaque;
|
|
} Parser;
|
|
|
|
static void evalExpression(Parser *p);
|
|
|
|
static void push(Parser *p, double d){
|
|
if(p->stack_index+1>= STACK_SIZE){
|
|
fprintf(stderr, "stack overflow in the parser\n");
|
|
return;
|
|
}
|
|
p->stack[ p->stack_index++ ]= d;
|
|
//printf("push %f\n", d); fflush(stdout);
|
|
}
|
|
|
|
static double pop(Parser *p){
|
|
if(p->stack_index<=0){
|
|
fprintf(stderr, "stack underflow in the parser\n");
|
|
return NAN;
|
|
}
|
|
//printf("pop\n"); fflush(stdout);
|
|
return p->stack[ --p->stack_index ];
|
|
}
|
|
|
|
static int strmatch(char *s, char *prefix){
|
|
int i;
|
|
for(i=0; prefix[i]; i++){
|
|
if(prefix[i] != s[i]) return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static void evalPrimary(Parser *p){
|
|
double d, d2=NAN;
|
|
char *next= p->s;
|
|
int i;
|
|
|
|
/* number */
|
|
d= strtod(p->s, &next);
|
|
if(next != p->s){
|
|
push(p, d);
|
|
p->s= next;
|
|
return;
|
|
}
|
|
|
|
/* named constants */
|
|
for(i=0; p->const_name[i]; i++){
|
|
if(strmatch(p->s, p->const_name[i])){
|
|
push(p, p->const_value[i]);
|
|
p->s+= strlen(p->const_name[i]);
|
|
return;
|
|
}
|
|
}
|
|
|
|
p->s= strchr(p->s, '(');
|
|
if(p->s==NULL){
|
|
fprintf(stderr, "Parser: missing ( in \"%s\"\n", next);
|
|
return;
|
|
}
|
|
p->s++; // "("
|
|
evalExpression(p);
|
|
d= pop(p);
|
|
p->s++; // ")" or ","
|
|
if(p->s[-1]== ','){
|
|
evalExpression(p);
|
|
d2= pop(p);
|
|
p->s++; // ")"
|
|
}
|
|
|
|
if( strmatch(next, "sinh" ) ) d= sinh(d);
|
|
else if( strmatch(next, "cosh" ) ) d= cosh(d);
|
|
else if( strmatch(next, "tanh" ) ) d= tanh(d);
|
|
else if( strmatch(next, "sin" ) ) d= sin(d);
|
|
else if( strmatch(next, "cos" ) ) d= cos(d);
|
|
else if( strmatch(next, "tan" ) ) d= tan(d);
|
|
else if( strmatch(next, "exp" ) ) d= exp(d);
|
|
else if( strmatch(next, "log" ) ) d= log(d);
|
|
else if( strmatch(next, "squish") ) d= 1/(1+exp(4*d));
|
|
else if( strmatch(next, "gauss" ) ) d= exp(-d*d/2)/sqrt(2*M_PI);
|
|
else if( strmatch(next, "abs" ) ) d= abs(d);
|
|
else if( strmatch(next, "max" ) ) d= d > d2 ? d : d2;
|
|
else if( strmatch(next, "min" ) ) d= d < d2 ? d : d2;
|
|
else if( strmatch(next, "gt" ) ) d= d > d2 ? 1.0 : 0.0;
|
|
else if( strmatch(next, "lt" ) ) d= d > d2 ? 0.0 : 1.0;
|
|
else if( strmatch(next, "eq" ) ) d= d == d2 ? 1.0 : 0.0;
|
|
// else if( strmatch(next, "l1" ) ) d= 1 + d2*(d - 1);
|
|
// else if( strmatch(next, "sq01" ) ) d= (d >= 0.0 && d <=1.0) ? 1.0 : 0.0;
|
|
else{
|
|
int error=1;
|
|
for(i=0; p->func1_name && p->func1_name[i]; i++){
|
|
if(strmatch(next, p->func1_name[i])){
|
|
d= p->func1[i](p->opaque, d);
|
|
error=0;
|
|
break;
|
|
}
|
|
}
|
|
|
|
for(i=0; p->func2_name && p->func2_name[i]; i++){
|
|
if(strmatch(next, p->func2_name[i])){
|
|
d= p->func2[i](p->opaque, d, d2);
|
|
error=0;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if(error){
|
|
fprintf(stderr, "Parser: unknown function in \"%s\"\n", next);
|
|
return;
|
|
}
|
|
}
|
|
|
|
if(p->s[-1]!= ')'){
|
|
fprintf(stderr, "Parser: missing ) in \"%s\"\n", next);
|
|
return;
|
|
}
|
|
push(p, d);
|
|
}
|
|
|
|
static void evalPow(Parser *p){
|
|
int neg= 0;
|
|
if(p->s[0]=='+') p->s++;
|
|
|
|
if(p->s[0]=='-'){
|
|
neg= 1;
|
|
p->s++;
|
|
}
|
|
|
|
if(p->s[0]=='('){
|
|
p->s++;;
|
|
evalExpression(p);
|
|
|
|
if(p->s[0]!=')')
|
|
fprintf(stderr, "Parser: missing )\n");
|
|
p->s++;
|
|
}else{
|
|
evalPrimary(p);
|
|
}
|
|
|
|
if(neg) push(p, -pop(p));
|
|
}
|
|
|
|
static void evalFactor(Parser *p){
|
|
evalPow(p);
|
|
while(p->s[0]=='^'){
|
|
double d;
|
|
|
|
p->s++;
|
|
evalPow(p);
|
|
d= pop(p);
|
|
push(p, pow(pop(p), d));
|
|
}
|
|
}
|
|
|
|
static void evalTerm(Parser *p){
|
|
evalFactor(p);
|
|
while(p->s[0]=='*' || p->s[0]=='/'){
|
|
int inv= p->s[0]=='/';
|
|
double d;
|
|
|
|
p->s++;
|
|
evalFactor(p);
|
|
d= pop(p);
|
|
if(inv) d= 1.0/d;
|
|
push(p, d * pop(p));
|
|
}
|
|
}
|
|
|
|
static void evalExpression(Parser *p){
|
|
evalTerm(p);
|
|
while(p->s[0]=='+' || p->s[0]=='-'){
|
|
int sign= p->s[0]=='-';
|
|
double d;
|
|
|
|
p->s++;
|
|
evalTerm(p);
|
|
d= pop(p);
|
|
if(sign) d= -d;
|
|
push(p, d + pop(p));
|
|
}
|
|
}
|
|
|
|
double ff_eval(char *s, double *const_value, char **const_name,
|
|
double (**func1)(void *, double), char **func1_name,
|
|
double (**func2)(void *, double, double), char **func2_name,
|
|
void *opaque){
|
|
Parser p;
|
|
|
|
p.stack_index=0;
|
|
p.s= s;
|
|
p.const_value= const_value;
|
|
p.const_name = const_name;
|
|
p.func1 = func1;
|
|
p.func1_name = func1_name;
|
|
p.func2 = func2;
|
|
p.func2_name = func2_name;
|
|
p.opaque = opaque;
|
|
|
|
evalExpression(&p);
|
|
return pop(&p);
|
|
}
|