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a3731cadfc
FFmpeg/libavcodec/eval.c
Stefano Sabatini a3731cadfc Avoid the use of the symbol ff_expr_s for referencing AVExpr. 
This way we have to deal only with struct AVExpr and AVExpr, which is
slightly less confusing as the association between the two symbols is
obvious.

Originally committed as revision 22839 to svn://svn.ffmpeg.org/ffmpeg/trunk
2010-04-11 18:44:51 +00:00

460 lines
13 KiB
C
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/*
* simple arithmetic expression evaluator
*
* Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
* Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
*
* This file is part of FFmpeg.
*
* FFmpeg 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 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file libavcodec/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>
#include "libavutil/mathematics.h"
#include "avcodec.h"
#include "eval.h"
typedef struct Parser{
int stack_index;
char *s;
const double *const_value;
const char * const *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
const char **func2_name; // NULL terminated
void *opaque;
const char **error;
#define VARS 10
double var[VARS];
} Parser;
static const int8_t si_prefixes['z' - 'E' + 1]={
['y'-'E']= -24,
['z'-'E']= -21,
['a'-'E']= -18,
['f'-'E']= -15,
['p'-'E']= -12,
['n'-'E']= - 9,
['u'-'E']= - 6,
['m'-'E']= - 3,
['c'-'E']= - 2,
['d'-'E']= - 1,
['h'-'E']= 2,
['k'-'E']= 3,
['K'-'E']= 3,
['M'-'E']= 6,
['G'-'E']= 9,
['T'-'E']= 12,
['P'-'E']= 15,
['E'-'E']= 18,
['Z'-'E']= 21,
['Y'-'E']= 24,
};
double av_strtod(const char *numstr, char **tail) {
double d;
char *next;
d = strtod(numstr, &next);
/* if parsing succeeded, check for and interpret postfixes */
if (next!=numstr) {
if(*next >= 'E' && *next <= 'z'){
int e= si_prefixes[*next - 'E'];
if(e){
if(next[1] == 'i'){
d*= pow( 2, e/0.3);
next+=2;
}else{
d*= pow(10, e);
next++;
}
}
}
if(*next=='B') {
d*=8;
next++;
}
}
/* if requested, fill in tail with the position after the last parsed
character */
if (tail)
*tail = next;
return d;
}
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;
}
struct AVExpr {
enum {
e_value, e_const, e_func0, e_func1, e_func2,
e_squish, e_gauss, e_ld,
e_mod, e_max, e_min, e_eq, e_gt, e_gte,
e_pow, e_mul, e_div, e_add,
e_last, e_st, e_while,
} type;
double value; // is sign in other types
union {
int const_index;
double (*func0)(double);
double (*func1)(void *, double);
double (*func2)(void *, double, double);
} a;
struct AVExpr *param[2];
};
static double eval_expr(Parser * p, AVExpr * e) {
switch (e->type) {
case e_value: return e->value;
case e_const: return e->value * p->const_value[e->a.const_index];
case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
case e_while: {
double d = NAN;
while(eval_expr(p, e->param[0]))
d=eval_expr(p, e->param[1]);
return d;
}
default: {
double d = eval_expr(p, e->param[0]);
double d2 = eval_expr(p, e->param[1]);
switch (e->type) {
case e_mod: return e->value * (d - floor(d/d2)*d2);
case e_max: return e->value * (d > d2 ? d : d2);
case e_min: return e->value * (d < d2 ? d : d2);
case e_eq: return e->value * (d == d2 ? 1.0 : 0.0);
case e_gt: return e->value * (d > d2 ? 1.0 : 0.0);
case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
case e_pow: return e->value * pow(d, d2);
case e_mul: return e->value * (d * d2);
case e_div: return e->value * (d / d2);
case e_add: return e->value * (d + d2);
case e_last:return e->value * d2;
case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
}
}
}
return NAN;
}
static AVExpr * parse_expr(Parser *p);
void ff_free_expr(AVExpr * e) {
if (!e) return;
ff_free_expr(e->param[0]);
ff_free_expr(e->param[1]);
av_freep(&e);
}
static AVExpr * parse_primary(Parser *p) {
AVExpr * d = av_mallocz(sizeof(AVExpr));
char *next= p->s;
int i;
if (!d)
return NULL;
/* number */
d->value = av_strtod(p->s, &next);
if(next != p->s){
d->type = e_value;
p->s= next;
return d;
}
d->value = 1;
/* named constants */
for(i=0; p->const_name && p->const_name[i]; i++){
if(strmatch(p->s, p->const_name[i])){
p->s+= strlen(p->const_name[i]);
d->type = e_const;
d->a.const_index = i;
return d;
}
}
p->s= strchr(p->s, '(');
if(p->s==NULL){
*p->error = "undefined constant or missing (";
p->s= next;
ff_free_expr(d);
return NULL;
}
p->s++; // "("
if (*next == '(') { // special case do-nothing
av_freep(&d);
d = parse_expr(p);
if(p->s[0] != ')'){
*p->error = "missing )";
ff_free_expr(d);
return NULL;
}
p->s++; // ")"
return d;
}
d->param[0] = parse_expr(p);
if(p->s[0]== ','){
p->s++; // ","
d->param[1] = parse_expr(p);
}
if(p->s[0] != ')'){
*p->error = "missing )";
ff_free_expr(d);
return NULL;
}
p->s++; // ")"
d->type = e_func0;
if( strmatch(next, "sinh" ) ) d->a.func0 = sinh;
else if( strmatch(next, "cosh" ) ) d->a.func0 = cosh;
else if( strmatch(next, "tanh" ) ) d->a.func0 = tanh;
else if( strmatch(next, "sin" ) ) d->a.func0 = sin;
else if( strmatch(next, "cos" ) ) d->a.func0 = cos;
else if( strmatch(next, "tan" ) ) d->a.func0 = tan;
else if( strmatch(next, "atan" ) ) d->a.func0 = atan;
else if( strmatch(next, "asin" ) ) d->a.func0 = asin;
else if( strmatch(next, "acos" ) ) d->a.func0 = acos;
else if( strmatch(next, "exp" ) ) d->a.func0 = exp;
else if( strmatch(next, "log" ) ) d->a.func0 = log;
else if( strmatch(next, "abs" ) ) d->a.func0 = fabs;
else if( strmatch(next, "squish") ) d->type = e_squish;
else if( strmatch(next, "gauss" ) ) d->type = e_gauss;
else if( strmatch(next, "mod" ) ) d->type = e_mod;
else if( strmatch(next, "max" ) ) d->type = e_max;
else if( strmatch(next, "min" ) ) d->type = e_min;
else if( strmatch(next, "eq" ) ) d->type = e_eq;
else if( strmatch(next, "gte" ) ) d->type = e_gte;
else if( strmatch(next, "gt" ) ) d->type = e_gt;
else if( strmatch(next, "lte" ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
else if( strmatch(next, "lt" ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
else if( strmatch(next, "ld" ) ) d->type = e_ld;
else if( strmatch(next, "st" ) ) d->type = e_st;
else if( strmatch(next, "while" ) ) d->type = e_while;
else {
for(i=0; p->func1_name && p->func1_name[i]; i++){
if(strmatch(next, p->func1_name[i])){
d->a.func1 = p->func1[i];
d->type = e_func1;
return d;
}
}
for(i=0; p->func2_name && p->func2_name[i]; i++){
if(strmatch(next, p->func2_name[i])){
d->a.func2 = p->func2[i];
d->type = e_func2;
return d;
}
}
*p->error = "unknown function";
ff_free_expr(d);
return NULL;
}
return d;
}
static AVExpr * new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1){
AVExpr * e = av_mallocz(sizeof(AVExpr));
if (!e)
return NULL;
e->type =type ;
e->value =value ;
e->param[0] =p0 ;
e->param[1] =p1 ;
return e;
}
static AVExpr * parse_pow(Parser *p, int *sign){
*sign= (*p->s == '+') - (*p->s == '-');
p->s += *sign&1;
return parse_primary(p);
}
static AVExpr * parse_factor(Parser *p){
int sign, sign2;
AVExpr * e = parse_pow(p, &sign);
while(p->s[0]=='^'){
p->s++;
e= new_eval_expr(e_pow, 1, e, parse_pow(p, &sign2));
if (!e)
return NULL;
if (e->param[1]) e->param[1]->value *= (sign2|1);
}
if (e) e->value *= (sign|1);
return e;
}
static AVExpr * parse_term(Parser *p){
AVExpr * e = parse_factor(p);
while(p->s[0]=='*' || p->s[0]=='/'){
int c= *p->s++;
e= new_eval_expr(c == '*' ? e_mul : e_div, 1, e, parse_factor(p));
if (!e)
return NULL;
}
return e;
}
static AVExpr * parse_subexpr(Parser *p) {
AVExpr * e = parse_term(p);
while(*p->s == '+' || *p->s == '-') {
e= new_eval_expr(e_add, 1, e, parse_term(p));
if (!e)
return NULL;
};
return e;
}
static AVExpr * parse_expr(Parser *p) {
AVExpr * e;
if(p->stack_index <= 0) //protect against stack overflows
return NULL;
p->stack_index--;
e = parse_subexpr(p);
while(*p->s == ';') {
p->s++;
e= new_eval_expr(e_last, 1, e, parse_subexpr(p));
if (!e)
return NULL;
};
p->stack_index++;
return e;
}
static int verify_expr(AVExpr * e) {
if (!e) return 0;
switch (e->type) {
case e_value:
case e_const: return 1;
case e_func0:
case e_func1:
case e_squish:
case e_ld:
case e_gauss: return verify_expr(e->param[0]);
default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
}
}
AVExpr * ff_parse(const char *s, const char * const *const_name,
double (**func1)(void *, double), const char **func1_name,
double (**func2)(void *, double, double), const char **func2_name,
const char **error){
Parser p;
AVExpr *e = NULL;
char *w = av_malloc(strlen(s) + 1);
char *wp = w;
if (!w)
goto end;
while (*s)
if (!isspace(*s++)) *wp++ = s[-1];
*wp++ = 0;
p.stack_index=100;
p.s= w;
p.const_name = const_name;
p.func1 = func1;
p.func1_name = func1_name;
p.func2 = func2;
p.func2_name = func2_name;
p.error= error;
e = parse_expr(&p);
if (!verify_expr(e)) {
ff_free_expr(e);
e = NULL;
}
end:
av_free(w);
return e;
}
double ff_parse_eval(AVExpr * e, const double *const_value, void *opaque) {
Parser p;
p.const_value= const_value;
p.opaque = opaque;
return eval_expr(&p, e);
}
double ff_eval2(const char *s, const double *const_value, const char * const *const_name,
double (**func1)(void *, double), const char **func1_name,
double (**func2)(void *, double, double), const char **func2_name,
void *opaque, const char **error){
AVExpr * e = ff_parse(s, const_name, func1, func1_name, func2, func2_name, error);
double d;
if (!e) return NAN;
d = ff_parse_eval(e, const_value, opaque);
ff_free_expr(e);
return d;
}
#ifdef TEST
#undef printf
static double const_values[]={
M_PI,
M_E,
0
};
static const char *const_names[]={
"PI",
"E",
0
};
int main(void){
int i;
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));
printf("%f == 0.931322575\n", ff_eval2("80G/80Gi", const_values, const_names, NULL, NULL, NULL, NULL, NULL, NULL));
for(i=0; i<1050; i++){
START_TIMER
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);
STOP_TIMER("ff_eval2")
}
return 0;
}
#endif
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