*
* 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
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
- /*
+/**
+ * @file eval.c
+ * simple arithmetic expression evaluator.
+ *
* see http://joe.hotchkiss.com/programming/eval/eval.html
*/
+#include "avcodec.h"
+#include "mpegvideo.h"
+
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
-#define STACK_SIZE 100
+#ifndef NAN
+ #define NAN 0
+#endif
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
typedef struct Parser{
- double stack[STACK_SIZE];
int stack_index;
char *s;
double *const_value;
- char **const_name; // NULL terminated
+ const char **const_name; // NULL terminated
double (**func1)(void *, double a); // NULL terminated
- char **func1_name; // 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 evalExpression(Parser *p);
-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){
+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){
+static double 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;
+ return d;
}
-
+
/* named constants */
- for(i=0; p->const_name[i]; i++){
+ for(i=0; p->const_name && 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;
+ return p->const_value[i];
}
}
-
+
p->s= strchr(p->s, '(');
if(p->s==NULL){
- fprintf(stderr, "Parser: missing ( in \"%s\"\n", next);
- return;
+ av_log(NULL, AV_LOG_ERROR, "Parser: missing ( in \"%s\"\n", next);
+ return NAN;
}
p->s++; // "("
- evalExpression(p);
- d= pop(p);
- p->s++; // ")" or ","
- if(p->s[-1]== ','){
- evalExpression(p);
- d2= pop(p);
- p->s++; // ")"
+ d= evalExpression(p);
+ if(p->s[0]== ','){
+ p->s++; // ","
+ d2= evalExpression(p);
}
-
+ if(p->s[0] != ')'){
+ av_log(NULL, AV_LOG_ERROR, "Parser: missing ) in \"%s\"\n", next);
+ return NAN;
+ }
+ 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, "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, "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, "(" ) ) d= d;
// 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;
+ return p->func1[i](p->opaque, d);
}
}
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;
+ return p->func2[i](p->opaque, d, d2);
}
}
- 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++;
+ av_log(NULL, AV_LOG_ERROR, "Parser: unknown function in \"%s\"\n", next);
+ return NAN;
}
-
- 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));
+ return d;
}
-static void evalFactor(Parser *p){
- evalPow(p);
- while(p->s[0]=='^'){
- double d;
+static double evalPow(Parser *p){
+ int sign= (*p->s == '+') - (*p->s == '-');
+ p->s += sign&1;
+ return (sign|1) * evalPrimary(p);
+}
+static double evalFactor(Parser *p){
+ double ret= evalPow(p);
+ while(p->s[0]=='^'){
p->s++;
- evalPow(p);
- d= pop(p);
- push(p, pow(pop(p), d));
+ ret= pow(ret, evalPow(p));
}
+ return ret;
}
-static void evalTerm(Parser *p){
- evalFactor(p);
+static double evalTerm(Parser *p){
+ double ret= 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));
+ if(*p->s++ == '*') ret*= evalFactor(p);
+ else ret/= evalFactor(p);
}
+ return ret;
}
-static void evalExpression(Parser *p){
- evalTerm(p);
- while(p->s[0]=='+' || p->s[0]=='-'){
- int sign= p->s[0]=='-';
- double d;
+static double evalExpression(Parser *p){
+ double ret= 0;
- p->s++;
- evalTerm(p);
- d= pop(p);
- if(sign) d= -d;
- push(p, d + pop(p));
- }
+ if(p->stack_index <= 0) //protect against stack overflows
+ return NAN;
+ p->stack_index--;
+
+ do{
+ ret += evalTerm(p);
+ }while(*p->s == '+' || *p->s == '-');
+
+ p->stack_index++;
+
+ return ret;
}
-double ff_eval(char *s, double *const_value, char **const_name,
- double (**func1)(void *, double), char **func1_name,
+double ff_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.stack_index=100;
p.s= s;
p.const_value= const_value;
p.const_name = const_name;
p.func2 = func2;
p.func2_name = func2_name;
p.opaque = opaque;
-
- evalExpression(&p);
- return pop(&p);
+
+ return evalExpression(&p);
+}
+
+#ifdef TEST
+#undef printf
+static double const_values[]={
+ M_PI,
+ M_E,
+ 0
+};
+static const char *const_names[]={
+ "PI",
+ "E",
+ 0
+};
+main(){
+ int i;
+ printf("%f == 12.7\n", ff_eval("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_values, const_names, NULL, NULL, NULL, NULL, NULL));
+
+ for(i=0; i<1050; i++){
+ START_TIMER
+ ff_eval("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_values, const_names, NULL, NULL, NULL, NULL, NULL);
+ STOP_TIMER("ff_eval")
+ }
}
+#endif
projects / ffmpeg / blobdiff