Commit cba0cd39 authored by Laurent Aimar's avatar Laurent Aimar

* eval.c: lalala ;)


git-svn-id: svn://svn.videolan.org/x264/trunk@43 df754926-b1dd-0310-bc7b-ec298dee348c
parent 8a5aa764
/*
* 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
*
*/
/**
* @file eval.c
* simple arithmetic expression evaluator.
*
* 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;
const char **const_name; // NULL terminated
double (**func1)(void *, double a); // NULL terminated
const 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(const char *s, const 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);
if(p->s[0]== ','){
p->s++; // ","
evalExpression(p);
d2= pop(p);
}
if(p->s[0] != ')'){
fprintf(stderr, "Parser: missing ) in \"%s\"\n", next);
return;
}
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= fabs(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, "gte" ) ) d= d >= d2 ? 1.0 : 0.0;
else if( strmatch(next, "lt" ) ) d= d > d2 ? 0.0 : 1.0;
else if( strmatch(next, "lte" ) ) 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;
}
}
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 x264_eval(char *s, double *const_value, const char **const_name,
double (**func1)(void *, double), const 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);
}
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