FFmpeg: libavcodec/eval.c Source File

00001 /*
00002  * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
00003  * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00029 #include "libavutil/avutil.h"
00030 #include "eval.h"
00031 
00032 typedef struct Parser{
00033     int stack_index;
00034     char *s;
00035     const double *const_value;
00036     const char * const *const_name;          // NULL terminated
00037     double (* const *func1)(void *, double a);           // NULL terminated
00038     const char * const *func1_name;          // NULL terminated
00039     double (* const *func2)(void *, double a, double b); // NULL terminated
00040     const char * const *func2_name;          // NULL terminated
00041     void *opaque;
00042     const char **error;
00043 #define VARS 10
00044     double var[VARS];
00045 } Parser;
00046 
00047 static const int8_t si_prefixes['z' - 'E' + 1]={
00048     ['y'-'E']= -24,
00049     ['z'-'E']= -21,
00050     ['a'-'E']= -18,
00051     ['f'-'E']= -15,
00052     ['p'-'E']= -12,
00053     ['n'-'E']= - 9,
00054     ['u'-'E']= - 6,
00055     ['m'-'E']= - 3,
00056     ['c'-'E']= - 2,
00057     ['d'-'E']= - 1,
00058     ['h'-'E']=   2,
00059     ['k'-'E']=   3,
00060     ['K'-'E']=   3,
00061     ['M'-'E']=   6,
00062     ['G'-'E']=   9,
00063     ['T'-'E']=  12,
00064     ['P'-'E']=  15,
00065     ['E'-'E']=  18,
00066     ['Z'-'E']=  21,
00067     ['Y'-'E']=  24,
00068 };
00069 
00070 double av_strtod(const char *numstr, char **tail) {
00071     double d;
00072     char *next;
00073     d = strtod(numstr, &next);
00074     /* if parsing succeeded, check for and interpret postfixes */
00075     if (next!=numstr) {
00076 
00077         if(*next >= 'E' && *next <= 'z'){
00078             int e= si_prefixes[*next - 'E'];
00079             if(e){
00080                 if(next[1] == 'i'){
00081                     d*= pow( 2, e/0.3);
00082                     next+=2;
00083                 }else{
00084                     d*= pow(10, e);
00085                     next++;
00086                 }
00087             }
00088         }
00089 
00090         if(*next=='B') {
00091             d*=8;
00092             next++;
00093         }
00094     }
00095     /* if requested, fill in tail with the position after the last parsed
00096        character */
00097     if (tail)
00098         *tail = next;
00099     return d;
00100 }
00101 
00102 static int strmatch(const char *s, const char *prefix){
00103     int i;
00104     for(i=0; prefix[i]; i++){
00105         if(prefix[i] != s[i]) return 0;
00106     }
00107     return 1;
00108 }
00109 
00110 struct AVExpr {
00111     enum {
00112         e_value, e_const, e_func0, e_func1, e_func2,
00113         e_squish, e_gauss, e_ld,
00114         e_mod, e_max, e_min, e_eq, e_gt, e_gte,
00115         e_pow, e_mul, e_div, e_add,
00116         e_last, e_st, e_while,
00117     } type;
00118     double value; // is sign in other types
00119     union {
00120         int const_index;
00121         double (*func0)(double);
00122         double (*func1)(void *, double);
00123         double (*func2)(void *, double, double);
00124     } a;
00125     struct AVExpr *param[2];
00126 };
00127 
00128 static double eval_expr(Parser * p, AVExpr * e) {
00129     switch (e->type) {
00130         case e_value:  return e->value;
00131         case e_const:  return e->value * p->const_value[e->a.const_index];
00132         case e_func0:  return e->value * e->a.func0(eval_expr(p, e->param[0]));
00133         case e_func1:  return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
00134         case e_func2:  return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
00135         case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
00136         case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
00137         case e_ld:     return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
00138         case e_while: {
00139             double d = NAN;
00140             while(eval_expr(p, e->param[0]))
00141                 d=eval_expr(p, e->param[1]);
00142             return d;
00143         }
00144         default: {
00145             double d = eval_expr(p, e->param[0]);
00146             double d2 = eval_expr(p, e->param[1]);
00147             switch (e->type) {
00148                 case e_mod: return e->value * (d - floor(d/d2)*d2);
00149                 case e_max: return e->value * (d >  d2 ?   d : d2);
00150                 case e_min: return e->value * (d <  d2 ?   d : d2);
00151                 case e_eq:  return e->value * (d == d2 ? 1.0 : 0.0);
00152                 case e_gt:  return e->value * (d >  d2 ? 1.0 : 0.0);
00153                 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
00154                 case e_pow: return e->value * pow(d, d2);
00155                 case e_mul: return e->value * (d * d2);
00156                 case e_div: return e->value * (d / d2);
00157                 case e_add: return e->value * (d + d2);
00158                 case e_last:return e->value * d2;
00159                 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
00160             }
00161         }
00162     }
00163     return NAN;
00164 }
00165 
00166 static AVExpr * parse_expr(Parser *p);
00167 
00168 void ff_free_expr(AVExpr * e) {
00169     if (!e) return;
00170     ff_free_expr(e->param[0]);
00171     ff_free_expr(e->param[1]);
00172     av_freep(&e);
00173 }
00174 
00175 static AVExpr * parse_primary(Parser *p) {
00176     AVExpr * d = av_mallocz(sizeof(AVExpr));
00177     char *next= p->s;
00178     int i;
00179 
00180     if (!d)
00181         return NULL;
00182 
00183     /* number */
00184     d->value = av_strtod(p->s, &next);
00185     if(next != p->s){
00186         d->type = e_value;
00187         p->s= next;
00188         return d;
00189     }
00190     d->value = 1;
00191 
00192     /* named constants */
00193     for(i=0; p->const_name && p->const_name[i]; i++){
00194         if(strmatch(p->s, p->const_name[i])){
00195             p->s+= strlen(p->const_name[i]);
00196             d->type = e_const;
00197             d->a.const_index = i;
00198             return d;
00199         }
00200     }
00201 
00202     p->s= strchr(p->s, '(');
00203     if(p->s==NULL){
00204         *p->error = "undefined constant or missing (";
00205         p->s= next;
00206         ff_free_expr(d);
00207         return NULL;
00208     }
00209     p->s++; // "("
00210     if (*next == '(') { // special case do-nothing
00211         av_freep(&d);
00212         d = parse_expr(p);
00213         if(p->s[0] != ')'){
00214             *p->error = "missing )";
00215             ff_free_expr(d);
00216             return NULL;
00217         }
00218         p->s++; // ")"
00219         return d;
00220     }
00221     d->param[0] = parse_expr(p);
00222     if(p->s[0]== ','){
00223         p->s++; // ","
00224         d->param[1] = parse_expr(p);
00225     }
00226     if(p->s[0] != ')'){
00227         *p->error = "missing )";
00228         ff_free_expr(d);
00229         return NULL;
00230     }
00231     p->s++; // ")"
00232 
00233     d->type = e_func0;
00234          if( strmatch(next, "sinh"  ) ) d->a.func0 = sinh;
00235     else if( strmatch(next, "cosh"  ) ) d->a.func0 = cosh;
00236     else if( strmatch(next, "tanh"  ) ) d->a.func0 = tanh;
00237     else if( strmatch(next, "sin"   ) ) d->a.func0 = sin;
00238     else if( strmatch(next, "cos"   ) ) d->a.func0 = cos;
00239     else if( strmatch(next, "tan"   ) ) d->a.func0 = tan;
00240     else if( strmatch(next, "atan"  ) ) d->a.func0 = atan;
00241     else if( strmatch(next, "asin"  ) ) d->a.func0 = asin;
00242     else if( strmatch(next, "acos"  ) ) d->a.func0 = acos;
00243     else if( strmatch(next, "exp"   ) ) d->a.func0 = exp;
00244     else if( strmatch(next, "log"   ) ) d->a.func0 = log;
00245     else if( strmatch(next, "abs"   ) ) d->a.func0 = fabs;
00246     else if( strmatch(next, "squish") ) d->type = e_squish;
00247     else if( strmatch(next, "gauss" ) ) d->type = e_gauss;
00248     else if( strmatch(next, "mod"   ) ) d->type = e_mod;
00249     else if( strmatch(next, "max"   ) ) d->type = e_max;
00250     else if( strmatch(next, "min"   ) ) d->type = e_min;
00251     else if( strmatch(next, "eq"    ) ) d->type = e_eq;
00252     else if( strmatch(next, "gte"   ) ) d->type = e_gte;
00253     else if( strmatch(next, "gt"    ) ) d->type = e_gt;
00254     else if( strmatch(next, "lte"   ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
00255     else if( strmatch(next, "lt"    ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
00256     else if( strmatch(next, "ld"    ) ) d->type = e_ld;
00257     else if( strmatch(next, "st"    ) ) d->type = e_st;
00258     else if( strmatch(next, "while" ) ) d->type = e_while;
00259     else {
00260         for(i=0; p->func1_name && p->func1_name[i]; i++){
00261             if(strmatch(next, p->func1_name[i])){
00262                 d->a.func1 = p->func1[i];
00263                 d->type = e_func1;
00264                 return d;
00265             }
00266         }
00267 
00268         for(i=0; p->func2_name && p->func2_name[i]; i++){
00269             if(strmatch(next, p->func2_name[i])){
00270                 d->a.func2 = p->func2[i];
00271                 d->type = e_func2;
00272                 return d;
00273             }
00274         }
00275 
00276         *p->error = "unknown function";
00277         ff_free_expr(d);
00278         return NULL;
00279     }
00280 
00281     return d;
00282 }
00283 
00284 static AVExpr * new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1){
00285     AVExpr * e = av_mallocz(sizeof(AVExpr));
00286     if (!e)
00287         return NULL;
00288     e->type     =type   ;
00289     e->value    =value  ;
00290     e->param[0] =p0     ;
00291     e->param[1] =p1     ;
00292     return e;
00293 }
00294 
00295 static AVExpr * parse_pow(Parser *p, int *sign){
00296     *sign= (*p->s == '+') - (*p->s == '-');
00297     p->s += *sign&1;
00298     return parse_primary(p);
00299 }
00300 
00301 static AVExpr * parse_factor(Parser *p){
00302     int sign, sign2;
00303     AVExpr * e = parse_pow(p, &sign);
00304     while(p->s[0]=='^'){
00305         p->s++;
00306         e= new_eval_expr(e_pow, 1, e, parse_pow(p, &sign2));
00307         if (!e)
00308             return NULL;
00309         if (e->param[1]) e->param[1]->value *= (sign2|1);
00310     }
00311     if (e) e->value *= (sign|1);
00312     return e;
00313 }
00314 
00315 static AVExpr * parse_term(Parser *p){
00316     AVExpr * e = parse_factor(p);
00317     while(p->s[0]=='*' || p->s[0]=='/'){
00318         int c= *p->s++;
00319         e= new_eval_expr(c == '*' ? e_mul : e_div, 1, e, parse_factor(p));
00320         if (!e)
00321             return NULL;
00322     }
00323     return e;
00324 }
00325 
00326 static AVExpr * parse_subexpr(Parser *p) {
00327     AVExpr * e = parse_term(p);
00328     while(*p->s == '+' || *p->s == '-') {
00329         e= new_eval_expr(e_add, 1, e, parse_term(p));
00330         if (!e)
00331             return NULL;
00332     };
00333 
00334     return e;
00335 }
00336 
00337 static AVExpr * parse_expr(Parser *p) {
00338     AVExpr * e;
00339 
00340     if(p->stack_index <= 0) //protect against stack overflows
00341         return NULL;
00342     p->stack_index--;
00343 
00344     e = parse_subexpr(p);
00345 
00346     while(*p->s == ';') {
00347         p->s++;
00348         e= new_eval_expr(e_last, 1, e, parse_subexpr(p));
00349         if (!e)
00350             return NULL;
00351     };
00352 
00353     p->stack_index++;
00354 
00355     return e;
00356 }
00357 
00358 static int verify_expr(AVExpr * e) {
00359     if (!e) return 0;
00360     switch (e->type) {
00361         case e_value:
00362         case e_const: return 1;
00363         case e_func0:
00364         case e_func1:
00365         case e_squish:
00366         case e_ld:
00367         case e_gauss: return verify_expr(e->param[0]);
00368         default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
00369     }
00370 }
00371 
00372 AVExpr *ff_parse_expr(const char *s, const char * const *const_name,
00373                double (* const *func1)(void *, double), const char * const *func1_name,
00374                double (* const *func2)(void *, double, double), const char * const *func2_name,
00375                const char **error){
00376     Parser p;
00377     AVExpr *e = NULL;
00378     char *w = av_malloc(strlen(s) + 1);
00379     char *wp = w;
00380 
00381     if (!w)
00382         goto end;
00383 
00384     while (*s)
00385         if (!isspace(*s++)) *wp++ = s[-1];
00386     *wp++ = 0;
00387 
00388     p.stack_index=100;
00389     p.s= w;
00390     p.const_name = const_name;
00391     p.func1      = func1;
00392     p.func1_name = func1_name;
00393     p.func2      = func2;
00394     p.func2_name = func2_name;
00395     p.error= error;
00396 
00397     e = parse_expr(&p);
00398     if (!verify_expr(e)) {
00399         ff_free_expr(e);
00400         e = NULL;
00401     }
00402 end:
00403     av_free(w);
00404     return e;
00405 }
00406 
00407 double ff_eval_expr(AVExpr * e, const double *const_value, void *opaque) {
00408     Parser p;
00409 
00410     p.const_value= const_value;
00411     p.opaque     = opaque;
00412     return eval_expr(&p, e);
00413 }
00414 
00415 double ff_parse_and_eval_expr(const char *s, const double *const_value, const char * const *const_name,
00416                double (* const *func1)(void *, double), const char * const *func1_name,
00417                double (* const *func2)(void *, double, double), const char * const *func2_name,
00418                void *opaque, const char **error){
00419     AVExpr * e = ff_parse_expr(s, const_name, func1, func1_name, func2, func2_name, error);
00420     double d;
00421     if (!e) return NAN;
00422     d = ff_eval_expr(e, const_value, opaque);
00423     ff_free_expr(e);
00424     return d;
00425 }
00426 
00427 #ifdef TEST
00428 #undef printf
00429 static double const_values[]={
00430     M_PI,
00431     M_E,
00432     0
00433 };
00434 static const char *const_names[]={
00435     "PI",
00436     "E",
00437     0
00438 };
00439 int main(void){
00440     int i;
00441     printf("%f == 12.7\n", ff_parse_and_eval_expr("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_values, const_names, NULL, NULL, NULL, NULL, NULL, NULL));
00442     printf("%f == 0.931322575\n", ff_parse_and_eval_expr("80G/80Gi", const_values, const_names, NULL, NULL, NULL, NULL, NULL, NULL));
00443 
00444     for(i=0; i<1050; i++){
00445         START_TIMER
00446             ff_parse_and_eval_expr("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_values, const_names, NULL, NULL, NULL, NULL, NULL, NULL);
00447         STOP_TIMER("ff_parse_and_eval_expr")
00448     }
00449     return 0;
00450 }
00451 #endif