Libav 0.7.1
libavutil/eval.c
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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 Libav.
00006  *
00007  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00029 #include "avutil.h"
00030 #include "eval.h"
00031 
00032 typedef struct Parser {
00033     const AVClass *class;
00034     int stack_index;
00035     char *s;
00036     const double *const_values;
00037     const char * const *const_names;          // NULL terminated
00038     double (* const *funcs1)(void *, double a);           // NULL terminated
00039     const char * const *func1_names;          // NULL terminated
00040     double (* const *funcs2)(void *, double a, double b); // NULL terminated
00041     const char * const *func2_names;          // NULL terminated
00042     void *opaque;
00043     int log_offset;
00044     void *log_ctx;
00045 #define VARS 10
00046     double var[VARS];
00047 } Parser;
00048 
00049 static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };
00050 
00051 static const int8_t si_prefixes['z' - 'E' + 1] = {
00052     ['y'-'E']= -24,
00053     ['z'-'E']= -21,
00054     ['a'-'E']= -18,
00055     ['f'-'E']= -15,
00056     ['p'-'E']= -12,
00057     ['n'-'E']= - 9,
00058     ['u'-'E']= - 6,
00059     ['m'-'E']= - 3,
00060     ['c'-'E']= - 2,
00061     ['d'-'E']= - 1,
00062     ['h'-'E']=   2,
00063     ['k'-'E']=   3,
00064     ['K'-'E']=   3,
00065     ['M'-'E']=   6,
00066     ['G'-'E']=   9,
00067     ['T'-'E']=  12,
00068     ['P'-'E']=  15,
00069     ['E'-'E']=  18,
00070     ['Z'-'E']=  21,
00071     ['Y'-'E']=  24,
00072 };
00073 
00074 double av_strtod(const char *numstr, char **tail)
00075 {
00076     double d;
00077     char *next;
00078     d = strtod(numstr, &next);
00079     /* if parsing succeeded, check for and interpret postfixes */
00080     if (next!=numstr) {
00081         if (*next >= 'E' && *next <= 'z') {
00082             int e= si_prefixes[*next - 'E'];
00083             if (e) {
00084                 if (next[1] == 'i') {
00085                     d*= pow( 2, e/0.3);
00086                     next+=2;
00087                 } else {
00088                     d*= pow(10, e);
00089                     next++;
00090                 }
00091             }
00092         }
00093 
00094         if (*next=='B') {
00095             d*=8;
00096             next++;
00097         }
00098     }
00099     /* if requested, fill in tail with the position after the last parsed
00100        character */
00101     if (tail)
00102         *tail = next;
00103     return d;
00104 }
00105 
00106 #define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')
00107 
00108 static int strmatch(const char *s, const char *prefix)
00109 {
00110     int i;
00111     for (i=0; prefix[i]; i++) {
00112         if (prefix[i] != s[i]) return 0;
00113     }
00114     /* return 1 only if the s identifier is terminated */
00115     return !IS_IDENTIFIER_CHAR(s[i]);
00116 }
00117 
00118 struct AVExpr {
00119     enum {
00120         e_value, e_const, e_func0, e_func1, e_func2,
00121         e_squish, e_gauss, e_ld, e_isnan,
00122         e_mod, e_max, e_min, e_eq, e_gt, e_gte,
00123         e_pow, e_mul, e_div, e_add,
00124         e_last, e_st, e_while, e_floor, e_ceil, e_trunc,
00125     } type;
00126     double value; // is sign in other types
00127     union {
00128         int const_index;
00129         double (*func0)(double);
00130         double (*func1)(void *, double);
00131         double (*func2)(void *, double, double);
00132     } a;
00133     struct AVExpr *param[2];
00134 };
00135 
00136 static double eval_expr(Parser *p, AVExpr *e)
00137 {
00138     switch (e->type) {
00139         case e_value:  return e->value;
00140         case e_const:  return e->value * p->const_values[e->a.const_index];
00141         case e_func0:  return e->value * e->a.func0(eval_expr(p, e->param[0]));
00142         case e_func1:  return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
00143         case e_func2:  return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
00144         case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
00145         case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
00146         case e_ld:     return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
00147         case e_isnan:  return e->value * !!isnan(eval_expr(p, e->param[0]));
00148         case e_floor:  return e->value * floor(eval_expr(p, e->param[0]));
00149         case e_ceil :  return e->value * ceil (eval_expr(p, e->param[0]));
00150         case e_trunc:  return e->value * trunc(eval_expr(p, e->param[0]));
00151         case e_while: {
00152             double d = NAN;
00153             while (eval_expr(p, e->param[0]))
00154                 d=eval_expr(p, e->param[1]);
00155             return d;
00156         }
00157         default: {
00158             double d = eval_expr(p, e->param[0]);
00159             double d2 = eval_expr(p, e->param[1]);
00160             switch (e->type) {
00161                 case e_mod: return e->value * (d - floor(d/d2)*d2);
00162                 case e_max: return e->value * (d >  d2 ?   d : d2);
00163                 case e_min: return e->value * (d <  d2 ?   d : d2);
00164                 case e_eq:  return e->value * (d == d2 ? 1.0 : 0.0);
00165                 case e_gt:  return e->value * (d >  d2 ? 1.0 : 0.0);
00166                 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
00167                 case e_pow: return e->value * pow(d, d2);
00168                 case e_mul: return e->value * (d * d2);
00169                 case e_div: return e->value * (d / d2);
00170                 case e_add: return e->value * (d + d2);
00171                 case e_last:return e->value * d2;
00172                 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
00173             }
00174         }
00175     }
00176     return NAN;
00177 }
00178 
00179 static int parse_expr(AVExpr **e, Parser *p);
00180 
00181 void av_expr_free(AVExpr *e)
00182 {
00183     if (!e) return;
00184     av_expr_free(e->param[0]);
00185     av_expr_free(e->param[1]);
00186     av_freep(&e);
00187 }
00188 
00189 static int parse_primary(AVExpr **e, Parser *p)
00190 {
00191     AVExpr *d = av_mallocz(sizeof(AVExpr));
00192     char *next = p->s, *s0 = p->s;
00193     int ret, i;
00194 
00195     if (!d)
00196         return AVERROR(ENOMEM);
00197 
00198     /* number */
00199     d->value = av_strtod(p->s, &next);
00200     if (next != p->s) {
00201         d->type = e_value;
00202         p->s= next;
00203         *e = d;
00204         return 0;
00205     }
00206     d->value = 1;
00207 
00208     /* named constants */
00209     for (i=0; p->const_names && p->const_names[i]; i++) {
00210         if (strmatch(p->s, p->const_names[i])) {
00211             p->s+= strlen(p->const_names[i]);
00212             d->type = e_const;
00213             d->a.const_index = i;
00214             *e = d;
00215             return 0;
00216         }
00217     }
00218 
00219     p->s= strchr(p->s, '(');
00220     if (p->s==NULL) {
00221         av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
00222         p->s= next;
00223         av_expr_free(d);
00224         return AVERROR(EINVAL);
00225     }
00226     p->s++; // "("
00227     if (*next == '(') { // special case do-nothing
00228         av_freep(&d);
00229         if ((ret = parse_expr(&d, p)) < 0)
00230             return ret;
00231         if (p->s[0] != ')') {
00232             av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
00233             av_expr_free(d);
00234             return AVERROR(EINVAL);
00235         }
00236         p->s++; // ")"
00237         *e = d;
00238         return 0;
00239     }
00240     if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
00241         av_expr_free(d);
00242         return ret;
00243     }
00244     if (p->s[0]== ',') {
00245         p->s++; // ","
00246         parse_expr(&d->param[1], p);
00247     }
00248     if (p->s[0] != ')') {
00249         av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
00250         av_expr_free(d);
00251         return AVERROR(EINVAL);
00252     }
00253     p->s++; // ")"
00254 
00255     d->type = e_func0;
00256          if (strmatch(next, "sinh"  )) d->a.func0 = sinh;
00257     else if (strmatch(next, "cosh"  )) d->a.func0 = cosh;
00258     else if (strmatch(next, "tanh"  )) d->a.func0 = tanh;
00259     else if (strmatch(next, "sin"   )) d->a.func0 = sin;
00260     else if (strmatch(next, "cos"   )) d->a.func0 = cos;
00261     else if (strmatch(next, "tan"   )) d->a.func0 = tan;
00262     else if (strmatch(next, "atan"  )) d->a.func0 = atan;
00263     else if (strmatch(next, "asin"  )) d->a.func0 = asin;
00264     else if (strmatch(next, "acos"  )) d->a.func0 = acos;
00265     else if (strmatch(next, "exp"   )) d->a.func0 = exp;
00266     else if (strmatch(next, "log"   )) d->a.func0 = log;
00267     else if (strmatch(next, "abs"   )) d->a.func0 = fabs;
00268     else if (strmatch(next, "squish")) d->type = e_squish;
00269     else if (strmatch(next, "gauss" )) d->type = e_gauss;
00270     else if (strmatch(next, "mod"   )) d->type = e_mod;
00271     else if (strmatch(next, "max"   )) d->type = e_max;
00272     else if (strmatch(next, "min"   )) d->type = e_min;
00273     else if (strmatch(next, "eq"    )) d->type = e_eq;
00274     else if (strmatch(next, "gte"   )) d->type = e_gte;
00275     else if (strmatch(next, "gt"    )) d->type = e_gt;
00276     else if (strmatch(next, "lte"   )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
00277     else if (strmatch(next, "lt"    )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
00278     else if (strmatch(next, "ld"    )) d->type = e_ld;
00279     else if (strmatch(next, "isnan" )) d->type = e_isnan;
00280     else if (strmatch(next, "st"    )) d->type = e_st;
00281     else if (strmatch(next, "while" )) d->type = e_while;
00282     else if (strmatch(next, "floor" )) d->type = e_floor;
00283     else if (strmatch(next, "ceil"  )) d->type = e_ceil;
00284     else if (strmatch(next, "trunc" )) d->type = e_trunc;
00285     else {
00286         for (i=0; p->func1_names && p->func1_names[i]; i++) {
00287             if (strmatch(next, p->func1_names[i])) {
00288                 d->a.func1 = p->funcs1[i];
00289                 d->type = e_func1;
00290                 *e = d;
00291                 return 0;
00292             }
00293         }
00294 
00295         for (i=0; p->func2_names && p->func2_names[i]; i++) {
00296             if (strmatch(next, p->func2_names[i])) {
00297                 d->a.func2 = p->funcs2[i];
00298                 d->type = e_func2;
00299                 *e = d;
00300                 return 0;
00301             }
00302         }
00303 
00304         av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
00305         av_expr_free(d);
00306         return AVERROR(EINVAL);
00307     }
00308 
00309     *e = d;
00310     return 0;
00311 }
00312 
00313 static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
00314 {
00315     AVExpr *e = av_mallocz(sizeof(AVExpr));
00316     if (!e)
00317         return NULL;
00318     e->type     =type   ;
00319     e->value    =value  ;
00320     e->param[0] =p0     ;
00321     e->param[1] =p1     ;
00322     return e;
00323 }
00324 
00325 static int parse_pow(AVExpr **e, Parser *p, int *sign)
00326 {
00327     *sign= (*p->s == '+') - (*p->s == '-');
00328     p->s += *sign&1;
00329     return parse_primary(e, p);
00330 }
00331 
00332 static int parse_factor(AVExpr **e, Parser *p)
00333 {
00334     int sign, sign2, ret;
00335     AVExpr *e0, *e1, *e2;
00336     if ((ret = parse_pow(&e0, p, &sign)) < 0)
00337         return ret;
00338     while(p->s[0]=='^'){
00339         e1 = e0;
00340         p->s++;
00341         if ((ret = parse_pow(&e2, p, &sign2)) < 0) {
00342             av_expr_free(e1);
00343             return ret;
00344         }
00345         e0 = new_eval_expr(e_pow, 1, e1, e2);
00346         if (!e0) {
00347             av_expr_free(e1);
00348             av_expr_free(e2);
00349             return AVERROR(ENOMEM);
00350         }
00351         if (e0->param[1]) e0->param[1]->value *= (sign2|1);
00352     }
00353     if (e0) e0->value *= (sign|1);
00354 
00355     *e = e0;
00356     return 0;
00357 }
00358 
00359 static int parse_term(AVExpr **e, Parser *p)
00360 {
00361     int ret;
00362     AVExpr *e0, *e1, *e2;
00363     if ((ret = parse_factor(&e0, p)) < 0)
00364         return ret;
00365     while (p->s[0]=='*' || p->s[0]=='/') {
00366         int c= *p->s++;
00367         e1 = e0;
00368         if ((ret = parse_factor(&e2, p)) < 0) {
00369             av_expr_free(e1);
00370             return ret;
00371         }
00372         e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
00373         if (!e0) {
00374             av_expr_free(e1);
00375             av_expr_free(e2);
00376             return AVERROR(ENOMEM);
00377         }
00378     }
00379     *e = e0;
00380     return 0;
00381 }
00382 
00383 static int parse_subexpr(AVExpr **e, Parser *p)
00384 {
00385     int ret;
00386     AVExpr *e0, *e1, *e2;
00387     if ((ret = parse_term(&e0, p)) < 0)
00388         return ret;
00389     while (*p->s == '+' || *p->s == '-') {
00390         e1 = e0;
00391         if ((ret = parse_term(&e2, p)) < 0) {
00392             av_expr_free(e1);
00393             return ret;
00394         }
00395         e0 = new_eval_expr(e_add, 1, e1, e2);
00396         if (!e0) {
00397             av_expr_free(e1);
00398             av_expr_free(e2);
00399             return AVERROR(ENOMEM);
00400         }
00401     };
00402 
00403     *e = e0;
00404     return 0;
00405 }
00406 
00407 static int parse_expr(AVExpr **e, Parser *p)
00408 {
00409     int ret;
00410     AVExpr *e0, *e1, *e2;
00411     if (p->stack_index <= 0) //protect against stack overflows
00412         return AVERROR(EINVAL);
00413     p->stack_index--;
00414 
00415     if ((ret = parse_subexpr(&e0, p)) < 0)
00416         return ret;
00417     while (*p->s == ';') {
00418         p->s++;
00419         e1 = e0;
00420         if ((ret = parse_subexpr(&e2, p)) < 0) {
00421             av_expr_free(e1);
00422             return ret;
00423         }
00424         e0 = new_eval_expr(e_last, 1, e1, e2);
00425         if (!e0) {
00426             av_expr_free(e1);
00427             av_expr_free(e2);
00428             return AVERROR(ENOMEM);
00429         }
00430     };
00431 
00432     p->stack_index++;
00433     *e = e0;
00434     return 0;
00435 }
00436 
00437 static int verify_expr(AVExpr *e)
00438 {
00439     if (!e) return 0;
00440     switch (e->type) {
00441         case e_value:
00442         case e_const: return 1;
00443         case e_func0:
00444         case e_func1:
00445         case e_squish:
00446         case e_ld:
00447         case e_gauss:
00448         case e_isnan:
00449         case e_floor:
00450         case e_ceil:
00451         case e_trunc:
00452             return verify_expr(e->param[0]);
00453         default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
00454     }
00455 }
00456 
00457 int av_expr_parse(AVExpr **expr, const char *s,
00458                   const char * const *const_names,
00459                   const char * const *func1_names, double (* const *funcs1)(void *, double),
00460                   const char * const *func2_names, double (* const *funcs2)(void *, double, double),
00461                   int log_offset, void *log_ctx)
00462 {
00463     Parser p;
00464     AVExpr *e = NULL;
00465     char *w = av_malloc(strlen(s) + 1);
00466     char *wp = w;
00467     const char *s0 = s;
00468     int ret = 0;
00469 
00470     if (!w)
00471         return AVERROR(ENOMEM);
00472 
00473     while (*s)
00474         if (!isspace(*s++)) *wp++ = s[-1];
00475     *wp++ = 0;
00476 
00477     p.class      = &class;
00478     p.stack_index=100;
00479     p.s= w;
00480     p.const_names = const_names;
00481     p.funcs1      = funcs1;
00482     p.func1_names = func1_names;
00483     p.funcs2      = funcs2;
00484     p.func2_names = func2_names;
00485     p.log_offset = log_offset;
00486     p.log_ctx    = log_ctx;
00487 
00488     if ((ret = parse_expr(&e, &p)) < 0)
00489         goto end;
00490     if (*p.s) {
00491         av_expr_free(e);
00492         av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
00493         ret = AVERROR(EINVAL);
00494         goto end;
00495     }
00496     if (!verify_expr(e)) {
00497         av_expr_free(e);
00498         ret = AVERROR(EINVAL);
00499         goto end;
00500     }
00501     *expr = e;
00502 end:
00503     av_free(w);
00504     return ret;
00505 }
00506 
00507 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
00508 {
00509     Parser p;
00510 
00511     p.const_values = const_values;
00512     p.opaque     = opaque;
00513     return eval_expr(&p, e);
00514 }
00515 
00516 int av_expr_parse_and_eval(double *d, const char *s,
00517                            const char * const *const_names, const double *const_values,
00518                            const char * const *func1_names, double (* const *funcs1)(void *, double),
00519                            const char * const *func2_names, double (* const *funcs2)(void *, double, double),
00520                            void *opaque, int log_offset, void *log_ctx)
00521 {
00522     AVExpr *e = NULL;
00523     int ret = av_expr_parse(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
00524 
00525     if (ret < 0) {
00526         *d = NAN;
00527         return ret;
00528     }
00529     *d = av_expr_eval(e, const_values, opaque);
00530     av_expr_free(e);
00531     return isnan(*d) ? AVERROR(EINVAL) : 0;
00532 }
00533 
00534 #ifdef TEST
00535 #undef printf
00536 static double const_values[] = {
00537     M_PI,
00538     M_E,
00539     0
00540 };
00541 
00542 static const char *const_names[] = {
00543     "PI",
00544     "E",
00545     0
00546 };
00547 
00548 int main(void)
00549 {
00550     int i;
00551     double d;
00552     const char **expr, *exprs[] = {
00553         "",
00554         "1;2",
00555         "-20",
00556         "-PI",
00557         "+PI",
00558         "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
00559         "80G/80Gi"
00560         "1k",
00561         "1Gi",
00562         "1gi",
00563         "1GiFoo",
00564         "1k+1k",
00565         "1Gi*3foo",
00566         "foo",
00567         "foo(",
00568         "foo()",
00569         "foo)",
00570         "sin",
00571         "sin(",
00572         "sin()",
00573         "sin)",
00574         "sin 10",
00575         "sin(1,2,3)",
00576         "sin(1 )",
00577         "1",
00578         "1foo",
00579         "bar + PI + E + 100f*2 + foo",
00580         "13k + 12f - foo(1, 2)",
00581         "1gi",
00582         "1Gi",
00583         "st(0, 123)",
00584         "st(1, 123); ld(1)",
00585         /* compute 1+2+...+N */
00586         "st(0, 1); while(lte(ld(0), 100), st(1, ld(1)+ld(0));st(0, ld(0)+1)); ld(1)",
00587         /* compute Fib(N) */
00588         "st(1, 1); st(2, 2); st(0, 1); while(lte(ld(0),10), st(3, ld(1)+ld(2)); st(1, ld(2)); st(2, ld(3)); st(0, ld(0)+1)); ld(3)",
00589         "while(0, 10)",
00590         "st(0, 1); while(lte(ld(0),100), st(1, ld(1)+ld(0)); st(0, ld(0)+1))",
00591         "isnan(1)",
00592         "isnan(NAN)",
00593         "floor(NAN)",
00594         "floor(123.123)",
00595         "floor(-123.123)",
00596         "trunc(123.123)",
00597         "trunc(-123.123)",
00598         "ceil(123.123)",
00599         "ceil(-123.123)",
00600         NULL
00601     };
00602 
00603     for (expr = exprs; *expr; expr++) {
00604         printf("Evaluating '%s'\n", *expr);
00605         av_expr_parse_and_eval(&d, *expr,
00606                                const_names, const_values,
00607                                NULL, NULL, NULL, NULL, NULL, 0, NULL);
00608         printf("'%s' -> %f\n\n", *expr, d);
00609     }
00610 
00611     av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
00612                            const_names, const_values,
00613                            NULL, NULL, NULL, NULL, NULL, 0, NULL);
00614     printf("%f == 12.7\n", d);
00615     av_expr_parse_and_eval(&d, "80G/80Gi",
00616                            const_names, const_values,
00617                            NULL, NULL, NULL, NULL, NULL, 0, NULL);
00618     printf("%f == 0.931322575\n", d);
00619 
00620     for (i=0; i<1050; i++) {
00621         START_TIMER
00622             av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
00623                                    const_names, const_values,
00624                                    NULL, NULL, NULL, NULL, NULL, 0, NULL);
00625         STOP_TIMER("av_expr_parse_and_eval")
00626     }
00627     return 0;
00628 }
00629 #endif