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FFmpeg/libavutil/eval.c

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  1. /*

  2.  * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>

  3.  * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>

  4.  *

  5.  * This file is part of FFmpeg.

  6.  *

  7.  * FFmpeg is free software; you can redistribute it and/or

  8.  * modify it under the terms of the GNU Lesser General Public

  9.  * License as published by the Free Software Foundation; either

  10.  * version 2.1 of the License, or (at your option) any later version.

  11.  *

  12.  * FFmpeg is distributed in the hope that it will be useful,

  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  15.  * Lesser General Public License for more details.

  16.  *

  17.  * You should have received a copy of the GNU Lesser General Public

  18.  * License along with FFmpeg; if not, write to the Free Software

  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  20.  */

  21. 

  22. /**

  23.  * @file

  24.  * simple arithmetic expression evaluator.

  25.  *

  26.  * see http://joe.hotchkiss.com/programming/eval/eval.html

  27.  */

  28. 

  29. #include <float.h>

  30. #include "attributes.h"

  31. #include "avutil.h"

  32. #include "common.h"

  33. #include "eval.h"

  34. #include "ffmath.h"

  35. #include "internal.h"

  36. #include "log.h"

  37. #include "mathematics.h"

  38. #include "time.h"

  39. #include "avstring.h"

  40. #include "timer.h"

  41. #include "reverse.h"

  42. 

  43. typedef struct Parser {

  44.     const AVClass *class;

  45.     int stack_index;

  46.     char *s;

  47.     const double *const_values;

  48.     const char * const *const_names;          // NULL terminated

  49.     double (* const *funcs1)(void *, double a);           // NULL terminated

  50.     const char * const *func1_names;          // NULL terminated

  51.     double (* const *funcs2)(void *, double a, double b); // NULL terminated

  52.     const char * const *func2_names;          // NULL terminated

  53.     void *opaque;

  54.     int log_offset;

  55.     void *log_ctx;

  56. #define VARS 10

  57.     double *var;

  58. } Parser;

  59. 

  60. static const AVClass eval_class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };

  61. 

  62. static const struct {

  63.     double bin_val;

  64.     double dec_val;

  65.     int8_t exp;

  66. } si_prefixes['z' - 'E' + 1] = {

  67.     ['y'-'E']= { 8.271806125530276749e-25, 1e-24, -24 },

  68.     ['z'-'E']= { 8.4703294725430034e-22, 1e-21, -21 },

  69.     ['a'-'E']= { 8.6736173798840355e-19, 1e-18, -18 },

  70.     ['f'-'E']= { 8.8817841970012523e-16, 1e-15, -15 },

  71.     ['p'-'E']= { 9.0949470177292824e-13, 1e-12, -12 },

  72.     ['n'-'E']= { 9.3132257461547852e-10, 1e-9,  -9 },

  73.     ['u'-'E']= { 9.5367431640625e-7, 1e-6, -6 },

  74.     ['m'-'E']= { 9.765625e-4, 1e-3, -3 },

  75.     ['c'-'E']= { 9.8431332023036951e-3, 1e-2, -2 },

  76.     ['d'-'E']= { 9.921256574801246e-2, 1e-1, -1 },

  77.     ['h'-'E']= { 1.0159366732596479e2, 1e2, 2 },

  78.     ['k'-'E']= { 1.024e3, 1e3, 3 },

  79.     ['K'-'E']= { 1.024e3, 1e3, 3 },

  80.     ['M'-'E']= { 1.048576e6, 1e6, 6 },

  81.     ['G'-'E']= { 1.073741824e9, 1e9, 9 },

  82.     ['T'-'E']= { 1.099511627776e12, 1e12, 12 },

  83.     ['P'-'E']= { 1.125899906842624e15, 1e15, 15 },

  84.     ['E'-'E']= { 1.152921504606847e18, 1e18, 18 },

  85.     ['Z'-'E']= { 1.1805916207174113e21, 1e21, 21 },

  86.     ['Y'-'E']= { 1.2089258196146292e24, 1e24, 24 },

  87. };

  88. 

  89. static const struct {

  90.     const char *name;

  91.     double value;

  92. } constants[] = {

  93.     { "E",   M_E   },

  94.     { "PI",  M_PI  },

  95.     { "PHI", M_PHI },

  96.     { "QP2LAMBDA", FF_QP2LAMBDA },

  97. };

  98. 

  99. double av_strtod(const char *numstr, char **tail)

  100. {

  101.     double d;

  102.     char *next;

  103.     if(numstr[0]=='0' && (numstr[1]|0x20)=='x') {

  104.         d = strtoul(numstr, &next, 16);

  105.     } else

  106.         d = strtod(numstr, &next);

  107.     /* if parsing succeeded, check for and interpret postfixes */

  108.     if (next!=numstr) {

  109.         if (next[0] == 'd' && next[1] == 'B') {

  110.             /* treat dB as decibels instead of decibytes */

  111.             d = ff_exp10(d / 20);

  112.             next += 2;

  113.         } else if (*next >= 'E' && *next <= 'z') {

  114.             int e= si_prefixes[*next - 'E'].exp;

  115.             if (e) {

  116.                 if (next[1] == 'i') {

  117.                     d*= si_prefixes[*next - 'E'].bin_val;

  118.                     next+=2;

  119.                 } else {

  120.                     d*= si_prefixes[*next - 'E'].dec_val;

  121.                     next++;

  122.                 }

  123.             }

  124.         }

  125. 

  126.         if (*next=='B') {

  127.             d*=8;

  128.             next++;

  129.         }

  130.     }

  131.     /* if requested, fill in tail with the position after the last parsed

  132.        character */

  133.     if (tail)

  134.         *tail = next;

  135.     return d;

  136. }

  137. 

  138. #define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')

  139. 

  140. static int strmatch(const char *s, const char *prefix)

  141. {

  142.     int i;

  143.     for (i=0; prefix[i]; i++) {

  144.         if (prefix[i] != s[i]) return 0;

  145.     }

  146.     /* return 1 only if the s identifier is terminated */

  147.     return !IS_IDENTIFIER_CHAR(s[i]);

  148. }

  149. 

  150. struct AVExpr {

  151.     enum {

  152.         e_value, e_const, e_func0, e_func1, e_func2,

  153.         e_squish, e_gauss, e_ld, e_isnan, e_isinf,

  154.         e_mod, e_max, e_min, e_eq, e_gt, e_gte, e_lte, e_lt,

  155.         e_pow, e_mul, e_div, e_add,

  156.         e_last, e_st, e_while, e_taylor, e_root, e_floor, e_ceil, e_trunc,

  157.         e_sqrt, e_not, e_random, e_hypot, e_gcd,

  158.         e_if, e_ifnot, e_print, e_bitand, e_bitor, e_between, e_clip

  159.     } type;

  160.     double value; // is sign in other types

  161.     union {

  162.         int const_index;

  163.         double (*func0)(double);

  164.         double (*func1)(void *, double);

  165.         double (*func2)(void *, double, double);

  166.     } a;

  167.     struct AVExpr *param[3];

  168.     double *var;

  169. };

  170. 

  171. static double etime(double v)

  172. {

  173.     return av_gettime() * 0.000001;

  174. }

  175. 

  176. static double eval_expr(Parser *p, AVExpr *e)

  177. {

  178.     switch (e->type) {

  179.         case e_value:  return e->value;

  180.         case e_const:  return e->value * p->const_values[e->a.const_index];

  181.         case e_func0:  return e->value * e->a.func0(eval_expr(p, e->param[0]));

  182.         case e_func1:  return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));

  183.         case e_func2:  return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));

  184.         case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));

  185.         case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }

  186.         case e_ld:     return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];

  187.         case e_isnan:  return e->value * !!isnan(eval_expr(p, e->param[0]));

  188.         case e_isinf:  return e->value * !!isinf(eval_expr(p, e->param[0]));

  189.         case e_floor:  return e->value * floor(eval_expr(p, e->param[0]));

  190.         case e_ceil :  return e->value * ceil (eval_expr(p, e->param[0]));

  191.         case e_trunc:  return e->value * trunc(eval_expr(p, e->param[0]));

  192.         case e_sqrt:   return e->value * sqrt (eval_expr(p, e->param[0]));

  193.         case e_not:    return e->value * (eval_expr(p, e->param[0]) == 0);

  194.         case e_if:     return e->value * (eval_expr(p, e->param[0]) ? eval_expr(p, e->param[1]) :

  195.                                           e->param[2] ? eval_expr(p, e->param[2]) : 0);

  196.         case e_ifnot:  return e->value * (!eval_expr(p, e->param[0]) ? eval_expr(p, e->param[1]) :

  197.                                           e->param[2] ? eval_expr(p, e->param[2]) : 0);

  198.         case e_clip: {

  199.             double x = eval_expr(p, e->param[0]);

  200.             double min = eval_expr(p, e->param[1]), max = eval_expr(p, e->param[2]);

  201.             if (isnan(min) || isnan(max) || isnan(x) || min > max)

  202.                 return NAN;

  203.             return e->value * av_clipd(eval_expr(p, e->param[0]), min, max);

  204.         }

  205.         case e_between: {

  206.             double d = eval_expr(p, e->param[0]);

  207.             return e->value * (d >= eval_expr(p, e->param[1]) &&

  208.                                d <= eval_expr(p, e->param[2]));

  209.         }

  210.         case e_print: {

  211.             double x = eval_expr(p, e->param[0]);

  212.             int level = e->param[1] ? av_clip(eval_expr(p, e->param[1]), INT_MIN, INT_MAX) : AV_LOG_INFO;

  213.             av_log(p, level, "%f\n", x);

  214.             return x;

  215.         }

  216.         case e_random:{

  217.             int idx= av_clip(eval_expr(p, e->param[0]), 0, VARS-1);

  218.             uint64_t r= isnan(p->var[idx]) ? 0 : p->var[idx];

  219.             r= r*1664525+1013904223;

  220.             p->var[idx]= r;

  221.             return e->value * (r * (1.0/UINT64_MAX));

  222.         }

  223.         case e_while: {

  224.             double d = NAN;

  225.             while (eval_expr(p, e->param[0]))

  226.                 d=eval_expr(p, e->param[1]);

  227.             return d;

  228.         }

  229.         case e_taylor: {

  230.             double t = 1, d = 0, v;

  231.             double x = eval_expr(p, e->param[1]);

  232.             int id = e->param[2] ? av_clip(eval_expr(p, e->param[2]), 0, VARS-1) : 0;

  233.             int i;

  234.             double var0 = p->var[id];

  235.             for(i=0; i<1000; i++) {

  236.                 double ld = d;

  237.                 p->var[id] = i;

  238.                 v = eval_expr(p, e->param[0]);

  239.                 d += t*v;

  240.                 if(ld==d && v)

  241.                     break;

  242.                 t *= x / (i+1);

  243.             }

  244.             p->var[id] = var0;

  245.             return d;

  246.         }

  247.         case e_root: {

  248.             int i, j;

  249.             double low = -1, high = -1, v, low_v = -DBL_MAX, high_v = DBL_MAX;

  250.             double var0 = p->var[0];

  251.             double x_max = eval_expr(p, e->param[1]);

  252.             for(i=-1; i<1024; i++) {

  253.                 if(i<255) {

  254.                     p->var[0] = ff_reverse[i&255]*x_max/255;

  255.                 } else {

  256.                     p->var[0] = x_max*pow(0.9, i-255);

  257.                     if (i&1) p->var[0] *= -1;

  258.                     if (i&2) p->var[0] += low;

  259.                     else     p->var[0] += high;

  260.                 }

  261.                 v = eval_expr(p, e->param[0]);

  262.                 if (v<=0 && v>low_v) {

  263.                     low    = p->var[0];

  264.                     low_v  = v;

  265.                 }

  266.                 if (v>=0 && v<high_v) {

  267.                     high   = p->var[0];

  268.                     high_v = v;

  269.                 }

  270.                 if (low>=0 && high>=0){

  271.                     for (j=0; j<1000; j++) {

  272.                         p->var[0] = (low+high)*0.5;

  273.                         if (low == p->var[0] || high == p->var[0])

  274.                             break;

  275.                         v = eval_expr(p, e->param[0]);

  276.                         if (v<=0) low = p->var[0];

  277.                         if (v>=0) high= p->var[0];

  278.                         if (isnan(v)) {

  279.                             low = high = v;

  280.                             break;

  281.                         }

  282.                     }

  283.                     break;

  284.                 }

  285.             }

  286.             p->var[0] = var0;

  287.             return -low_v<high_v ? low : high;

  288.         }

  289.         default: {

  290.             double d = eval_expr(p, e->param[0]);

  291.             double d2 = eval_expr(p, e->param[1]);

  292.             switch (e->type) {

  293.                 case e_mod: return e->value * (d - floor((!CONFIG_FTRAPV || d2) ? d / d2 : d * INFINITY) * d2);

  294.                 case e_gcd: return e->value * av_gcd(d,d2);

  295.                 case e_max: return e->value * (d >  d2 ?   d : d2);

  296.                 case e_min: return e->value * (d <  d2 ?   d : d2);

  297.                 case e_eq:  return e->value * (d == d2 ? 1.0 : 0.0);

  298.                 case e_gt:  return e->value * (d >  d2 ? 1.0 : 0.0);

  299.                 case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);

  300.                 case e_lt:  return e->value * (d <  d2 ? 1.0 : 0.0);

  301.                 case e_lte: return e->value * (d <= d2 ? 1.0 : 0.0);

  302.                 case e_pow: return e->value * pow(d, d2);

  303.                 case e_mul: return e->value * (d * d2);

  304.                 case e_div: return e->value * ((!CONFIG_FTRAPV || d2 ) ? (d / d2) : d * INFINITY);

  305.                 case e_add: return e->value * (d + d2);

  306.                 case e_last:return e->value * d2;

  307.                 case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);

  308.                 case e_hypot:return e->value * hypot(d, d2);

  309.                 case e_bitand: return isnan(d) || isnan(d2) ? NAN : e->value * ((long int)d & (long int)d2);

  310.                 case e_bitor:  return isnan(d) || isnan(d2) ? NAN : e->value * ((long int)d | (long int)d2);

  311.             }

  312.         }

  313.     }

  314.     return NAN;

  315. }

  316. 

  317. static int parse_expr(AVExpr **e, Parser *p);

  318. 

  319. void av_expr_free(AVExpr *e)

  320. {

  321.     if (!e) return;

  322.     av_expr_free(e->param[0]);

  323.     av_expr_free(e->param[1]);

  324.     av_expr_free(e->param[2]);

  325.     av_freep(&e->var);

  326.     av_freep(&e);

  327. }

  328. 

  329. static int parse_primary(AVExpr **e, Parser *p)

  330. {

  331.     AVExpr *d = av_mallocz(sizeof(AVExpr));

  332.     char *next = p->s, *s0 = p->s;

  333.     int ret, i;

  334. 

  335.     if (!d)

  336.         return AVERROR(ENOMEM);

  337. 

  338.     /* number */

  339.     d->value = av_strtod(p->s, &next);

  340.     if (next != p->s) {

  341.         d->type = e_value;

  342.         p->s= next;

  343.         *e = d;

  344.         return 0;

  345.     }

  346.     d->value = 1;

  347. 

  348.     /* named constants */

  349.     for (i=0; p->const_names && p->const_names[i]; i++) {

  350.         if (strmatch(p->s, p->const_names[i])) {

  351.             p->s+= strlen(p->const_names[i]);

  352.             d->type = e_const;

  353.             d->a.const_index = i;

  354.             *e = d;

  355.             return 0;

  356.         }

  357.     }

  358.     for (i = 0; i < FF_ARRAY_ELEMS(constants); i++) {

  359.         if (strmatch(p->s, constants[i].name)) {

  360.             p->s += strlen(constants[i].name);

  361.             d->type = e_value;

  362.             d->value = constants[i].value;

  363.             *e = d;

  364.             return 0;

  365.         }

  366.     }

  367. 

  368.     p->s= strchr(p->s, '(');

  369.     if (!p->s) {

  370.         av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);

  371.         p->s= next;

  372.         av_expr_free(d);

  373.         return AVERROR(EINVAL);

  374.     }

  375.     p->s++; // "("

  376.     if (*next == '(') { // special case do-nothing

  377.         av_freep(&d);

  378.         if ((ret = parse_expr(&d, p)) < 0)

  379.             return ret;

  380.         if (p->s[0] != ')') {

  381.             av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);

  382.             av_expr_free(d);

  383.             return AVERROR(EINVAL);

  384.         }

  385.         p->s++; // ")"

  386.         *e = d;

  387.         return 0;

  388.     }

  389.     if ((ret = parse_expr(&(d->param[0]), p)) < 0) {

  390.         av_expr_free(d);

  391.         return ret;

  392.     }

  393.     if (p->s[0]== ',') {

  394.         p->s++; // ","

  395.         parse_expr(&d->param[1], p);

  396.     }

  397.     if (p->s[0]== ',') {

  398.         p->s++; // ","

  399.         parse_expr(&d->param[2], p);

  400.     }

  401.     if (p->s[0] != ')') {

  402.         av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);

  403.         av_expr_free(d);

  404.         return AVERROR(EINVAL);

  405.     }

  406.     p->s++; // ")"

  407. 

  408.     d->type = e_func0;

  409.          if (strmatch(next, "sinh"  )) d->a.func0 = sinh;

  410.     else if (strmatch(next, "cosh"  )) d->a.func0 = cosh;

  411.     else if (strmatch(next, "tanh"  )) d->a.func0 = tanh;

  412.     else if (strmatch(next, "sin"   )) d->a.func0 = sin;

  413.     else if (strmatch(next, "cos"   )) d->a.func0 = cos;

  414.     else if (strmatch(next, "tan"   )) d->a.func0 = tan;

  415.     else if (strmatch(next, "atan"  )) d->a.func0 = atan;

  416.     else if (strmatch(next, "asin"  )) d->a.func0 = asin;

  417.     else if (strmatch(next, "acos"  )) d->a.func0 = acos;

  418.     else if (strmatch(next, "exp"   )) d->a.func0 = exp;

  419.     else if (strmatch(next, "log"   )) d->a.func0 = log;

  420.     else if (strmatch(next, "abs"   )) d->a.func0 = fabs;

  421.     else if (strmatch(next, "time"  )) d->a.func0 = etime;

  422.     else if (strmatch(next, "squish")) d->type = e_squish;

  423.     else if (strmatch(next, "gauss" )) d->type = e_gauss;

  424.     else if (strmatch(next, "mod"   )) d->type = e_mod;

  425.     else if (strmatch(next, "max"   )) d->type = e_max;

  426.     else if (strmatch(next, "min"   )) d->type = e_min;

  427.     else if (strmatch(next, "eq"    )) d->type = e_eq;

  428.     else if (strmatch(next, "gte"   )) d->type = e_gte;

  429.     else if (strmatch(next, "gt"    )) d->type = e_gt;

  430.     else if (strmatch(next, "lte"   )) d->type = e_lte;

  431.     else if (strmatch(next, "lt"    )) d->type = e_lt;

  432.     else if (strmatch(next, "ld"    )) d->type = e_ld;

  433.     else if (strmatch(next, "isnan" )) d->type = e_isnan;

  434.     else if (strmatch(next, "isinf" )) d->type = e_isinf;

  435.     else if (strmatch(next, "st"    )) d->type = e_st;

  436.     else if (strmatch(next, "while" )) d->type = e_while;

  437.     else if (strmatch(next, "taylor")) d->type = e_taylor;

  438.     else if (strmatch(next, "root"  )) d->type = e_root;

  439.     else if (strmatch(next, "floor" )) d->type = e_floor;

  440.     else if (strmatch(next, "ceil"  )) d->type = e_ceil;

  441.     else if (strmatch(next, "trunc" )) d->type = e_trunc;

  442.     else if (strmatch(next, "sqrt"  )) d->type = e_sqrt;

  443.     else if (strmatch(next, "not"   )) d->type = e_not;

  444.     else if (strmatch(next, "pow"   )) d->type = e_pow;

  445.     else if (strmatch(next, "print" )) d->type = e_print;

  446.     else if (strmatch(next, "random")) d->type = e_random;

  447.     else if (strmatch(next, "hypot" )) d->type = e_hypot;

  448.     else if (strmatch(next, "gcd"   )) d->type = e_gcd;

  449.     else if (strmatch(next, "if"    )) d->type = e_if;

  450.     else if (strmatch(next, "ifnot" )) d->type = e_ifnot;

  451.     else if (strmatch(next, "bitand")) d->type = e_bitand;

  452.     else if (strmatch(next, "bitor" )) d->type = e_bitor;

  453.     else if (strmatch(next, "between"))d->type = e_between;

  454.     else if (strmatch(next, "clip"  )) d->type = e_clip;

  455.     else {

  456.         for (i=0; p->func1_names && p->func1_names[i]; i++) {

  457.             if (strmatch(next, p->func1_names[i])) {

  458.                 d->a.func1 = p->funcs1[i];

  459.                 d->type = e_func1;

  460.                 *e = d;

  461.                 return 0;

  462.             }

  463.         }

  464. 

  465.         for (i=0; p->func2_names && p->func2_names[i]; i++) {

  466.             if (strmatch(next, p->func2_names[i])) {

  467.                 d->a.func2 = p->funcs2[i];

  468.                 d->type = e_func2;

  469.                 *e = d;

  470.                 return 0;

  471.             }

  472.         }

  473. 

  474.         av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);

  475.         av_expr_free(d);

  476.         return AVERROR(EINVAL);

  477.     }

  478. 

  479.     *e = d;

  480.     return 0;

  481. }

  482. 

  483. static AVExpr *make_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)

  484. {

  485.     AVExpr *e = av_mallocz(sizeof(AVExpr));

  486.     if (!e)

  487.         return NULL;

  488.     e->type     =type   ;

  489.     e->value    =value  ;

  490.     e->param[0] =p0     ;

  491.     e->param[1] =p1     ;

  492.     return e;

  493. }

  494. 

  495. static int parse_pow(AVExpr **e, Parser *p, int *sign)

  496. {

  497.     *sign= (*p->s == '+') - (*p->s == '-');

  498.     p->s += *sign&1;

  499.     return parse_primary(e, p);

  500. }

  501. 

  502. static int parse_dB(AVExpr **e, Parser *p, int *sign)

  503. {

  504.     /* do not filter out the negative sign when parsing a dB value.

  505.        for example, -3dB is not the same as -(3dB) */

  506.     if (*p->s == '-') {

  507.         char *next;

  508.         double av_unused ignored = strtod(p->s, &next);

  509.         if (next != p->s && next[0] == 'd' && next[1] == 'B') {

  510.             *sign = 0;

  511.             return parse_primary(e, p);

  512.         }

  513.     }

  514.     return parse_pow(e, p, sign);

  515. }

  516. 

  517. static int parse_factor(AVExpr **e, Parser *p)

  518. {

  519.     int sign, sign2, ret;

  520.     AVExpr *e0, *e1, *e2;

  521.     if ((ret = parse_dB(&e0, p, &sign)) < 0)

  522.         return ret;

  523.     while(p->s[0]=='^'){

  524.         e1 = e0;

  525.         p->s++;

  526.         if ((ret = parse_dB(&e2, p, &sign2)) < 0) {

  527.             av_expr_free(e1);

  528.             return ret;

  529.         }

  530.         e0 = make_eval_expr(e_pow, 1, e1, e2);

  531.         if (!e0) {

  532.             av_expr_free(e1);

  533.             av_expr_free(e2);

  534.             return AVERROR(ENOMEM);

  535.         }

  536.         if (e0->param[1]) e0->param[1]->value *= (sign2|1);

  537.     }

  538.     if (e0) e0->value *= (sign|1);

  539. 

  540.     *e = e0;

  541.     return 0;

  542. }

  543. 

  544. static int parse_term(AVExpr **e, Parser *p)

  545. {

  546.     int ret;

  547.     AVExpr *e0, *e1, *e2;

  548.     if ((ret = parse_factor(&e0, p)) < 0)

  549.         return ret;

  550.     while (p->s[0]=='*' || p->s[0]=='/') {

  551.         int c= *p->s++;

  552.         e1 = e0;

  553.         if ((ret = parse_factor(&e2, p)) < 0) {

  554.             av_expr_free(e1);

  555.             return ret;

  556.         }

  557.         e0 = make_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);

  558.         if (!e0) {

  559.             av_expr_free(e1);

  560.             av_expr_free(e2);

  561.             return AVERROR(ENOMEM);

  562.         }

  563.     }

  564.     *e = e0;

  565.     return 0;

  566. }

  567. 

  568. static int parse_subexpr(AVExpr **e, Parser *p)

  569. {

  570.     int ret;

  571.     AVExpr *e0, *e1, *e2;

  572.     if ((ret = parse_term(&e0, p)) < 0)

  573.         return ret;

  574.     while (*p->s == '+' || *p->s == '-') {

  575.         e1 = e0;

  576.         if ((ret = parse_term(&e2, p)) < 0) {

  577.             av_expr_free(e1);

  578.             return ret;

  579.         }

  580.         e0 = make_eval_expr(e_add, 1, e1, e2);

  581.         if (!e0) {

  582.             av_expr_free(e1);

  583.             av_expr_free(e2);

  584.             return AVERROR(ENOMEM);

  585.         }

  586.     };

  587. 

  588.     *e = e0;

  589.     return 0;

  590. }

  591. 

  592. static int parse_expr(AVExpr **e, Parser *p)

  593. {

  594.     int ret;

  595.     AVExpr *e0, *e1, *e2;

  596.     if (p->stack_index <= 0) //protect against stack overflows

  597.         return AVERROR(EINVAL);

  598.     p->stack_index--;

  599. 

  600.     if ((ret = parse_subexpr(&e0, p)) < 0)

  601.         return ret;

  602.     while (*p->s == ';') {

  603.         p->s++;

  604.         e1 = e0;

  605.         if ((ret = parse_subexpr(&e2, p)) < 0) {

  606.             av_expr_free(e1);

  607.             return ret;

  608.         }

  609.         e0 = make_eval_expr(e_last, 1, e1, e2);

  610.         if (!e0) {

  611.             av_expr_free(e1);

  612.             av_expr_free(e2);

  613.             return AVERROR(ENOMEM);

  614.         }

  615.     };

  616. 

  617.     p->stack_index++;

  618.     *e = e0;

  619.     return 0;

  620. }

  621. 

  622. static int verify_expr(AVExpr *e)

  623. {

  624.     if (!e) return 0;

  625.     switch (e->type) {

  626.         case e_value:

  627.         case e_const: return 1;

  628.         case e_func0:

  629.         case e_func1:

  630.         case e_squish:

  631.         case e_ld:

  632.         case e_gauss:

  633.         case e_isnan:

  634.         case e_isinf:

  635.         case e_floor:

  636.         case e_ceil:

  637.         case e_trunc:

  638.         case e_sqrt:

  639.         case e_not:

  640.         case e_random:

  641.             return verify_expr(e->param[0]) && !e->param[1];

  642.         case e_print:

  643.             return verify_expr(e->param[0])

  644.                    && (!e->param[1] || verify_expr(e->param[1]));

  645.         case e_if:

  646.         case e_ifnot:

  647.         case e_taylor:

  648.             return verify_expr(e->param[0]) && verify_expr(e->param[1])

  649.                    && (!e->param[2] || verify_expr(e->param[2]));

  650.         case e_between:

  651.         case e_clip:

  652.             return verify_expr(e->param[0]) &&

  653.                    verify_expr(e->param[1]) &&

  654.                    verify_expr(e->param[2]);

  655.         default: return verify_expr(e->param[0]) && verify_expr(e->param[1]) && !e->param[2];

  656.     }

  657. }

  658. 

  659. int av_expr_parse(AVExpr **expr, const char *s,

  660.                   const char * const *const_names,

  661.                   const char * const *func1_names, double (* const *funcs1)(void *, double),

  662.                   const char * const *func2_names, double (* const *funcs2)(void *, double, double),

  663.                   int log_offset, void *log_ctx)

  664. {

  665.     Parser p = { 0 };

  666.     AVExpr *e = NULL;

  667.     char *w = av_malloc(strlen(s) + 1);

  668.     char *wp = w;

  669.     const char *s0 = s;

  670.     int ret = 0;

  671. 

  672.     if (!w)

  673.         return AVERROR(ENOMEM);

  674. 

  675.     while (*s)

  676.         if (!av_isspace(*s++)) *wp++ = s[-1];

  677.     *wp++ = 0;

  678. 

  679.     p.class      = &eval_class;

  680.     p.stack_index=100;

  681.     p.s= w;

  682.     p.const_names = const_names;

  683.     p.funcs1      = funcs1;

  684.     p.func1_names = func1_names;

  685.     p.funcs2      = funcs2;

  686.     p.func2_names = func2_names;

  687.     p.log_offset = log_offset;

  688.     p.log_ctx    = log_ctx;

  689. 

  690.     if ((ret = parse_expr(&e, &p)) < 0)

  691.         goto end;

  692.     if (*p.s) {

  693.         av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);

  694.         ret = AVERROR(EINVAL);

  695.         goto end;

  696.     }

  697.     if (!verify_expr(e)) {

  698.         ret = AVERROR(EINVAL);

  699.         goto end;

  700.     }

  701.     e->var= av_mallocz(sizeof(double) *VARS);

  702.     if (!e->var) {

  703.         ret = AVERROR(ENOMEM);

  704.         goto end;

  705.     }

  706.     *expr = e;

  707.     e = NULL;

  708. end:

  709.     av_expr_free(e);

  710.     av_free(w);

  711.     return ret;

  712. }

  713. 

  714. double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)

  715. {

  716.     Parser p = { 0 };

  717.     p.var= e->var;

  718. 

  719.     p.const_values = const_values;

  720.     p.opaque     = opaque;

  721.     return eval_expr(&p, e);

  722. }

  723. 

  724. int av_expr_parse_and_eval(double *d, const char *s,

  725.                            const char * const *const_names, const double *const_values,

  726.                            const char * const *func1_names, double (* const *funcs1)(void *, double),

  727.                            const char * const *func2_names, double (* const *funcs2)(void *, double, double),

  728.                            void *opaque, int log_offset, void *log_ctx)

  729. {

  730.     AVExpr *e = NULL;

  731.     int ret = av_expr_parse(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);

  732. 

  733.     if (ret < 0) {

  734.         *d = NAN;

  735.         return ret;

  736.     }

  737.     *d = av_expr_eval(e, const_values, opaque);

  738.     av_expr_free(e);

  739.     return isnan(*d) ? AVERROR(EINVAL) : 0;

  740. }