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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 = {

  61.     .class_name                = "Eval",

  62.     .item_name                 = av_default_item_name,

  63.     .option                    = NULL,

  64.     .version                   = LIBAVUTIL_VERSION_INT,

  65.     .log_level_offset_offset   = offsetof(Parser, log_offset),

  66.     .parent_log_context_offset = offsetof(Parser, log_ctx),

  67. };

  68. 

  69. static const struct {

  70.     double bin_val;

  71.     double dec_val;

  72.     int8_t exp;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  94. };

  95. 

  96. static const struct {

  97.     const char *name;

  98.     double value;

  99. } constants[] = {

  100.     { "E",   M_E   },

  101.     { "PI",  M_PI  },

  102.     { "PHI", M_PHI },

  103.     { "QP2LAMBDA", FF_QP2LAMBDA },

  104. };

  105. 

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

  107. {

  108.     double d;

  109.     char *next;

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

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

  112.     } else

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

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

  115.     if (next!=numstr) {

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

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

  118.             d = ff_exp10(d / 20);

  119.             next += 2;

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

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

  122.             if (e) {

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

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

  125.                     next+=2;

  126.                 } else {

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

  128.                     next++;

  129.                 }

  130.             }

  131.         }

  132. 

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

  134.             d*=8;

  135.             next++;

  136.         }

  137.     }

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

  139.        character */

  140.     if (tail)

  141.         *tail = next;

  142.     return d;

  143. }

  144. 

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

  146. 

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

  148. {

  149.     int i;

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

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

  152.     }

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

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

  155. }

  156. 

  157. struct AVExpr {

  158.     enum {

  159.         e_value, e_const, e_func0, e_func1, e_func2,

  160.         e_squish, e_gauss, e_ld, e_isnan, e_isinf,

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

  162.         e_pow, e_mul, e_div, e_add,

  163.         e_last, e_st, e_while, e_taylor, e_root, e_floor, e_ceil, e_trunc, e_round,

  164.         e_sqrt, e_not, e_random, e_hypot, e_gcd,

  165.         e_if, e_ifnot, e_print, e_bitand, e_bitor, e_between, e_clip, e_atan2, e_lerp,

  166.         e_sgn,

  167.     } type;

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

  169.     union {

  170.         int const_index;

  171.         double (*func0)(double);

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

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

  174.     } a;

  175.     struct AVExpr *param[3];

  176.     double *var;

  177. };

  178. 

  179. static double etime(double v)

  180. {

  181.     return av_gettime() * 0.000001;

  182. }

  183. 

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

  185. {

  186.     switch (e->type) {

  187.         case e_value:  return e->value;

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

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

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

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

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

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

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

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

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

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

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

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

  200.         case e_round:  return e->value * round(eval_expr(p, e->param[0]));

  201.         case e_sgn:    return e->value * FFDIFFSIGN(eval_expr(p, e->param[0]), 0);

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

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

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

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

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

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

  208.         case e_clip: {

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

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

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

  212.                 return NAN;

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

  214.         }

  215.         case e_between: {

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

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

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

  219.         }

  220.         case e_lerp: {

  221.             double v0 = eval_expr(p, e->param[0]);

  222.             double v1 = eval_expr(p, e->param[1]);

  223.             double f  = eval_expr(p, e->param[2]);

  224.             return v0 + (v1 - v0) * f;

  225.         }

  226.         case e_print: {

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

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

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

  230.             return x;

  231.         }

  232.         case e_random:{

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

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

  235.             r= r*1664525+1013904223;

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

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

  238.         }

  239.         case e_while: {

  240.             double d = NAN;

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

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

  243.             return d;

  244.         }

  245.         case e_taylor: {

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

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

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

  249.             int i;

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

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

  252.                 double ld = d;

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

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

  255.                 d += t*v;

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

  257.                     break;

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

  259.             }

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

  261.             return d;

  262.         }

  263.         case e_root: {

  264.             int i, j;

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

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

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

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

  269.                 if(i<255) {

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

  271.                 } else {

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

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

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

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

  276.                 }

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

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

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

  280.                     low_v  = v;

  281.                 }

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

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

  284.                     high_v = v;

  285.                 }

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

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

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

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

  290.                             break;

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

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

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

  294.                         if (isnan(v)) {

  295.                             low = high = v;

  296.                             break;

  297.                         }

  298.                     }

  299.                     break;

  300.                 }

  301.             }

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

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

  304.         }

  305.         default: {

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

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

  308.             switch (e->type) {

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  325.                 case e_atan2:return e->value * atan2(d, d2);

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

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

  328.             }

  329.         }

  330.     }

  331.     return NAN;

  332. }

  333. 

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

  335. 

  336. void av_expr_free(AVExpr *e)

  337. {

  338.     if (!e) return;

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

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

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

  342.     av_freep(&e->var);

  343.     av_freep(&e);

  344. }

  345. 

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

  347. {

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

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

  350.     int ret, i;

  351. 

  352.     if (!d)

  353.         return AVERROR(ENOMEM);

  354. 

  355.     /* number */

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

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

  358.         d->type = e_value;

  359.         p->s= next;

  360.         *e = d;

  361.         return 0;

  362.     }

  363.     d->value = 1;

  364. 

  365.     /* named constants */

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

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

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

  369.             d->type = e_const;

  370.             d->a.const_index = i;

  371.             *e = d;

  372.             return 0;

  373.         }

  374.     }

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

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

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

  378.             d->type = e_value;

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

  380.             *e = d;

  381.             return 0;

  382.         }

  383.     }

  384. 

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

  386.     if (!p->s) {

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

  388.         p->s= next;

  389.         av_expr_free(d);

  390.         return AVERROR(EINVAL);

  391.     }

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

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

  394.         av_freep(&d);

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

  396.             return ret;

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

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

  399.             av_expr_free(d);

  400.             return AVERROR(EINVAL);

  401.         }

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

  403.         *e = d;

  404.         return 0;

  405.     }

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

  407.         av_expr_free(d);

  408.         return ret;

  409.     }

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

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

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

  413.     }

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

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

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

  417.     }

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

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

  420.         av_expr_free(d);

  421.         return AVERROR(EINVAL);

  422.     }

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

  424. 

  425.     d->type = e_func0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  459.     else if (strmatch(next, "round" )) d->type = e_round;

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

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

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

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

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

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

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

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

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

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

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

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

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

  473.     else if (strmatch(next, "atan2" )) d->type = e_atan2;

  474.     else if (strmatch(next, "lerp"  )) d->type = e_lerp;

  475.     else if (strmatch(next, "sgn"   )) d->type = e_sgn;

  476.     else {

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

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

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

  480.                 d->type = e_func1;

  481.                 *e = d;

  482.                 return 0;

  483.             }

  484.         }

  485. 

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

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

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

  489.                 d->type = e_func2;

  490.                 *e = d;

  491.                 return 0;

  492.             }

  493.         }

  494. 

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

  496.         av_expr_free(d);

  497.         return AVERROR(EINVAL);

  498.     }

  499. 

  500.     *e = d;

  501.     return 0;

  502. }

  503. 

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

  505. {

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

  507.     if (!e)

  508.         return NULL;

  509.     e->type     =type   ;

  510.     e->value    =value  ;

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

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

  513.     return e;

  514. }

  515. 

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

  517. {

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

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

  520.     return parse_primary(e, p);

  521. }

  522. 

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

  524. {

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

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

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

  528.         char *next;

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

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

  531.             *sign = 0;

  532.             return parse_primary(e, p);

  533.         }

  534.     }

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

  536. }

  537. 

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

  539. {

  540.     int sign, sign2, ret;

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

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

  543.         return ret;

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

  545.         e1 = e0;

  546.         p->s++;

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

  548.             av_expr_free(e1);

  549.             return ret;

  550.         }

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

  552.         if (!e0) {

  553.             av_expr_free(e1);

  554.             av_expr_free(e2);

  555.             return AVERROR(ENOMEM);

  556.         }

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

  558.     }

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

  560. 

  561.     *e = e0;

  562.     return 0;

  563. }

  564. 

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

  566. {

  567.     int ret;

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

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

  570.         return ret;

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

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

  573.         e1 = e0;

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

  575.             av_expr_free(e1);

  576.             return ret;

  577.         }

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

  579.         if (!e0) {

  580.             av_expr_free(e1);

  581.             av_expr_free(e2);

  582.             return AVERROR(ENOMEM);

  583.         }

  584.     }

  585.     *e = e0;

  586.     return 0;

  587. }

  588. 

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

  590. {

  591.     int ret;

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

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

  594.         return ret;

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

  596.         e1 = e0;

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

  598.             av_expr_free(e1);

  599.             return ret;

  600.         }

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

  602.         if (!e0) {

  603.             av_expr_free(e1);

  604.             av_expr_free(e2);

  605.             return AVERROR(ENOMEM);

  606.         }

  607.     };

  608. 

  609.     *e = e0;

  610.     return 0;

  611. }

  612. 

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

  614. {

  615.     int ret;

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

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

  618.         return AVERROR(EINVAL);

  619.     p->stack_index--;

  620. 

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

  622.         return ret;

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

  624.         p->s++;

  625.         e1 = e0;

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

  627.             av_expr_free(e1);

  628.             return ret;

  629.         }

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

  631.         if (!e0) {

  632.             av_expr_free(e1);

  633.             av_expr_free(e2);

  634.             return AVERROR(ENOMEM);

  635.         }

  636.     };

  637. 

  638.     p->stack_index++;

  639.     *e = e0;

  640.     return 0;

  641. }

  642. 

  643. static int verify_expr(AVExpr *e)

  644. {

  645.     if (!e) return 0;

  646.     switch (e->type) {

  647.         case e_value:

  648.         case e_const: return 1;

  649.         case e_func0:

  650.         case e_func1:

  651.         case e_squish:

  652.         case e_ld:

  653.         case e_gauss:

  654.         case e_isnan:

  655.         case e_isinf:

  656.         case e_floor:

  657.         case e_ceil:

  658.         case e_trunc:

  659.         case e_round:

  660.         case e_sqrt:

  661.         case e_not:

  662.         case e_random:

  663.         case e_sgn:

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

  665.         case e_print:

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

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

  668.         case e_if:

  669.         case e_ifnot:

  670.         case e_taylor:

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

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

  673.         case e_between:

  674.         case e_clip:

  675.         case e_lerp:

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

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

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

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

  680.     }

  681. }

  682. 

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

  684.                   const char * const *const_names,

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

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

  687.                   int log_offset, void *log_ctx)

  688. {

  689.     Parser p = { 0 };

  690.     AVExpr *e = NULL;

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

  692.     char *wp = w;

  693.     const char *s0 = s;

  694.     int ret = 0;

  695. 

  696.     if (!w)

  697.         return AVERROR(ENOMEM);

  698. 

  699.     while (*s)

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

  701.     *wp++ = 0;

  702. 

  703.     p.class      = &eval_class;

  704.     p.stack_index=100;

  705.     p.s= w;

  706.     p.const_names = const_names;

  707.     p.funcs1      = funcs1;

  708.     p.func1_names = func1_names;

  709.     p.funcs2      = funcs2;

  710.     p.func2_names = func2_names;

  711.     p.log_offset = log_offset;

  712.     p.log_ctx    = log_ctx;

  713. 

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

  715.         goto end;

  716.     if (*p.s) {

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

  718.         ret = AVERROR(EINVAL);

  719.         goto end;

  720.     }

  721.     if (!verify_expr(e)) {

  722.         ret = AVERROR(EINVAL);

  723.         goto end;

  724.     }

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

  726.     if (!e->var) {

  727.         ret = AVERROR(ENOMEM);

  728.         goto end;

  729.     }

  730.     *expr = e;

  731.     e = NULL;

  732. end:

  733.     av_expr_free(e);

  734.     av_free(w);

  735.     return ret;

  736. }

  737. 

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

  739. {

  740.     Parser p = { 0 };

  741.     p.var= e->var;

  742. 

  743.     p.const_values = const_values;

  744.     p.opaque     = opaque;

  745.     return eval_expr(&p, e);

  746. }

  747. 

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

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

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

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

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

  753. {

  754.     AVExpr *e = NULL;

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

  756. 

  757.     if (ret < 0) {

  758.         *d = NAN;

  759.         return ret;

  760.     }

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

  762.     av_expr_free(e);

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

  764. }