text: /*
   * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
   * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  /**
   * @file
   * simple arithmetic expression evaluator.
   *
   * see http://joe.hotchkiss.com/programming/eval/eval.html
   */
  
  #include <float.h>
  #include "avutil.h"
  #include "common.h"
  #include "eval.h"
  #include "log.h"
  #include "mathematics.h"
  
  typedef struct Parser {
      const AVClass *class;
      int stack_index;
      char *s;
      const double *const_values;
      const char * const *const_names;          // NULL terminated
      double (* const *funcs1)(void *, double a);           // NULL terminated
      const char * const *func1_names;          // NULL terminated
      double (* const *funcs2)(void *, double a, double b); // NULL terminated
      const char * const *func2_names;          // NULL terminated
      void *opaque;
      int log_offset;
      void *log_ctx;
  #define VARS 10
      double *var;
  } Parser;
  
  static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };
  
  static const int8_t si_prefixes['z' - 'E' + 1] = {
      ['y'-'E']= -24,
      ['z'-'E']= -21,
      ['a'-'E']= -18,
      ['f'-'E']= -15,
      ['p'-'E']= -12,
      ['n'-'E']= - 9,
      ['u'-'E']= - 6,
      ['m'-'E']= - 3,
      ['c'-'E']= - 2,
      ['d'-'E']= - 1,
      ['h'-'E']=   2,
      ['k'-'E']=   3,
      ['K'-'E']=   3,
      ['M'-'E']=   6,
      ['G'-'E']=   9,
      ['T'-'E']=  12,
      ['P'-'E']=  15,
      ['E'-'E']=  18,
      ['Z'-'E']=  21,
      ['Y'-'E']=  24,
  };
  
  static const struct {
      const char *name;
      double value;
  } constants[] = {
      { "E",   M_E   },
      { "PI",  M_PI  },
      { "PHI", M_PHI },
  };
  
  double av_strtod(const char *numstr, char **tail)
  {
      double d;
      char *next;
      if(numstr[0]=='0' && (numstr[1]|0x20)=='x') {
          d = strtoul(numstr, &next, 16);
      } else
          d = strtod(numstr, &next);
      /* if parsing succeeded, check for and interpret postfixes */
      if (next!=numstr) {
          if (next[0] == 'd' && next[1] == 'B') {
              /* treat dB as decibels instead of decibytes */
              d = pow(10, d / 20);
              next += 2;
          } else if (*next >= 'E' && *next <= 'z') {
              int e= si_prefixes[*next - 'E'];
              if (e) {
                  if (next[1] == 'i') {
                      d*= pow( 2, e/0.3);
                      next+=2;
                  } else {
                      d*= pow(10, e);
                      next++;
                  }
              }
          }
  
          if (*next=='B') {
              d*=8;
              next++;
          }
      }
      /* if requested, fill in tail with the position after the last parsed
         character */
      if (tail)
          *tail = next;
      return d;
  }
  
  #define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')
  
  static int strmatch(const char *s, const char *prefix)
  {
      int i;
      for (i=0; prefix[i]; i++) {
          if (prefix[i] != s[i]) return 0;
      }
      /* return 1 only if the s identifier is terminated */
      return !IS_IDENTIFIER_CHAR(s[i]);
  }
  
  struct AVExpr {
      enum {
          e_value, e_const, e_func0, e_func1, e_func2,
          e_squish, e_gauss, e_ld, e_isnan, e_isinf,
          e_mod, e_max, e_min, e_eq, e_gt, e_gte,
          e_pow, e_mul, e_div, e_add,
          e_last, e_st, e_while, e_taylor, e_root, e_floor, e_ceil, e_trunc,
          e_sqrt, e_not, e_random, e_hypot, e_gcd,
          e_if, e_ifnot,
      } type;
      double value; // is sign in other types
      union {
          int const_index;
          double (*func0)(double);
          double (*func1)(void *, double);
          double (*func2)(void *, double, double);
      } a;
      struct AVExpr *param[3];
      double *var;
  };
  
  static double eval_expr(Parser *p, AVExpr *e)
  {
      switch (e->type) {
          case e_value:  return e->value;
          case e_const:  return e->value * p->const_values[e->a.const_index];
          case e_func0:  return e->value * e->a.func0(eval_expr(p, e->param[0]));
          case e_func1:  return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
          case e_func2:  return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
          case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
          case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
          case e_ld:     return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
          case e_isnan:  return e->value * !!isnan(eval_expr(p, e->param[0]));
          case e_isinf:  return e->value * !!isinf(eval_expr(p, e->param[0]));
          case e_floor:  return e->value * floor(eval_expr(p, e->param[0]));
          case e_ceil :  return e->value * ceil (eval_expr(p, e->param[0]));
          case e_trunc:  return e->value * trunc(eval_expr(p, e->param[0]));
          case e_sqrt:   return e->value * sqrt (eval_expr(p, e->param[0]));
          case e_not:    return e->value * (eval_expr(p, e->param[0]) == 0);
          case e_if:     return e->value * ( eval_expr(p, e->param[0]) ? eval_expr(p, e->param[1]) : 0);
          case e_ifnot:  return e->value * (!eval_expr(p, e->param[0]) ? eval_expr(p, e->param[1]) : 0);
          case e_random:{
              int idx= av_clip(eval_expr(p, e->param[0]), 0, VARS-1);
              uint64_t r= isnan(p->var[idx]) ? 0 : p->var[idx];
              r= r*1664525+1013904223;
              p->var[idx]= r;
              return e->value * (r * (1.0/UINT64_MAX));
          }
          case e_while: {
              double d = NAN;
              while (eval_expr(p, e->param[0]))
                  d=eval_expr(p, e->param[1]);
              return d;
          }
          case e_taylor: {
              double t = 1, d = 0, v;
              double x = eval_expr(p, e->param[1]);
              int id = e->param[2] ? av_clip(eval_expr(p, e->param[2]), 0, VARS-1) : 0;
              int i;
              double var0 = p->var[id];
              for(i=0; i<1000; i++) {
                  double ld = d;
                  p->var[id] = i;
                  v = eval_expr(p, e->param[0]);
                  d += t*v;
                  if(ld==d && v)
                      break;
                  t *= x / (i+1);
              }
              p->var[id] = var0;
              return d;
          }
          case e_root: {
              int i, j;
              double low = -1, high = -1, v, low_v = -DBL_MAX, high_v = DBL_MAX;
              double var0 = p->var[0];
              double x_max = eval_expr(p, e->param[1]);
              for(i=-1; i<1024; i++) {
                  if(i<255) {
                      p->var[0] = av_reverse[i&255]*x_max/255;
                  } else {
                      p->var[0] = x_max*pow(0.9, i-255);
                      if (i&1) p->var[0] *= -1;
                      if (i&2) p->var[0] += low;
                      else     p->var[0] += high;
                  }
                  v = eval_expr(p, e->param[0]);
                  if (v<=0 && v>low_v) {
                      low    = p->var[0];
                      low_v  = v;
                  }
                  if (v>=0 && v<high_v) {
                      high   = p->var[0];
                      high_v = v;
                  }
                  if (low>=0 && high>=0){
                      for (j=0; j<1000; j++) {
                          p->var[0] = (low+high)*0.5;
                          if (low == p->var[0] || high == p->var[0])
                              break;
                          v = eval_expr(p, e->param[0]);
                          if (v<=0) low = p->var[0];
                          if (v>=0) high= p->var[0];
                          if (isnan(v)) {
                              low = high = v;
                              break;
                          }
                      }
                      break;
                  }
              }
              p->var[0] = var0;
              return -low_v<high_v ? low : high;
          }
          default: {
              double d = eval_expr(p, e->param[0]);
              double d2 = eval_expr(p, e->param[1]);
              switch (e->type) {
                  case e_mod: return e->value * (d - floor((!CONFIG_FTRAPV || d2) ? d / d2 : d * INFINITY) * d2);
                  case e_gcd: return e->value * av_gcd(d,d2);
                  case e_max: return e->value * (d >  d2 ?   d : d2);
                  case e_min: return e->value * (d <  d2 ?   d : d2);
                  case e_eq:  return e->value * (d == d2 ? 1.0 : 0.0);
                  case e_gt:  return e->value * (d >  d2 ? 1.0 : 0.0);
                  case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
                  case e_pow: return e->value * pow(d, d2);
                  case e_mul: return e->value * (d * d2);
                  case e_div: return e->value * ((!CONFIG_FTRAPV || d2 ) ? (d / d2) : d * INFINITY);
                  case e_add: return e->value * (d + d2);
                  case e_last:return e->value * d2;
                  case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
                  case e_hypot:return e->value * (sqrt(d*d + d2*d2));
              }
          }
      }
      return NAN;
  }
  
  static int parse_expr(AVExpr **e, Parser *p);
  
  void av_expr_free(AVExpr *e)
  {
      if (!e) return;
      av_expr_free(e->param[0]);
      av_expr_free(e->param[1]);
      av_expr_free(e->param[2]);
      av_freep(&e->var);
      av_freep(&e);
  }
  
  static int parse_primary(AVExpr **e, Parser *p)
  {
      AVExpr *d = av_mallocz(sizeof(AVExpr));
      char *next = p->s, *s0 = p->s;
      int ret, i;
  
      if (!d)
          return AVERROR(ENOMEM);
  
      /* number */
      d->value = av_strtod(p->s, &next);
      if (next != p->s) {
          d->type = e_value;
          p->s= next;
          *e = d;
          return 0;
      }
      d->value = 1;
  
      /* named constants */
      for (i=0; p->const_names && p->const_names[i]; i++) {
          if (strmatch(p->s, p->const_names[i])) {
              p->s+= strlen(p->const_names[i]);
              d->type = e_const;
              d->a.const_index = i;
              *e = d;
              return 0;
          }
      }
      for (i = 0; i < FF_ARRAY_ELEMS(constants); i++) {
          if (strmatch(p->s, constants[i].name)) {
              p->s += strlen(constants[i].name);
              d->type = e_value;
              d->value = constants[i].value;
              *e = d;
              return 0;
          }
      }
  
      p->s= strchr(p->s, '(');
      if (p->s==NULL) {
          av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
          p->s= next;
          av_expr_free(d);
          return AVERROR(EINVAL);
      }
      p->s++; // "("
      if (*next == '(') { // special case do-nothing
          av_freep(&d);
          if ((ret = parse_expr(&d, p)) < 0)
              return ret;
          if (p->s[0] != ')') {
              av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
              av_expr_free(d);
              return AVERROR(EINVAL);
          }
          p->s++; // ")"
          *e = d;
          return 0;
      }
      if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
          av_expr_free(d);
          return ret;
      }
      if (p->s[0]== ',') {
          p->s++; // ","
          parse_expr(&d->param[1], p);
      }
      if (p->s[0]== ',') {
          p->s++; // ","
          parse_expr(&d->param[2], p);
      }
      if (p->s[0] != ')') {
          av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
          av_expr_free(d);
          return AVERROR(EINVAL);
      }
      p->s++; // ")"
  
      d->type = e_func0;
           if (strmatch(next, "sinh"  )) d->a.func0 = sinh;
      else if (strmatch(next, "cosh"  )) d->a.func0 = cosh;
      else if (strmatch(next, "tanh"  )) d->a.func0 = tanh;
      else if (strmatch(next, "sin"   )) d->a.func0 = sin;
      else if (strmatch(next, "cos"   )) d->a.func0 = cos;
      else if (strmatch(next, "tan"   )) d->a.func0 = tan;
      else if (strmatch(next, "atan"  )) d->a.func0 = atan;
      else if (strmatch(next, "asin"  )) d->a.func0 = asin;
      else if (strmatch(next, "acos"  )) d->a.func0 = acos;
      else if (strmatch(next, "exp"   )) d->a.func0 = exp;
      else if (strmatch(next, "log"   )) d->a.func0 = log;
      else if (strmatch(next, "abs"   )) d->a.func0 = fabs;
      else if (strmatch(next, "squish")) d->type = e_squish;
      else if (strmatch(next, "gauss" )) d->type = e_gauss;
      else if (strmatch(next, "mod"   )) d->type = e_mod;
      else if (strmatch(next, "max"   )) d->type = e_max;
      else if (strmatch(next, "min"   )) d->type = e_min;
      else if (strmatch(next, "eq"    )) d->type = e_eq;
      else if (strmatch(next, "gte"   )) d->type = e_gte;
      else if (strmatch(next, "gt"    )) d->type = e_gt;
      else if (strmatch(next, "lte"   )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
      else if (strmatch(next, "lt"    )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
      else if (strmatch(next, "ld"    )) d->type = e_ld;
      else if (strmatch(next, "isnan" )) d->type = e_isnan;
      else if (strmatch(next, "isinf" )) d->type = e_isinf;
      else if (strmatch(next, "st"    )) d->type = e_st;
      else if (strmatch(next, "while" )) d->type = e_while;
      else if (strmatch(next, "taylor")) d->type = e_taylor;
      else if (strmatch(next, "root"  )) d->type = e_root;
      else if (strmatch(next, "floor" )) d->type = e_floor;
      else if (strmatch(next, "ceil"  )) d->type = e_ceil;
      else if (strmatch(next, "trunc" )) d->type = e_trunc;
      else if (strmatch(next, "sqrt"  )) d->type = e_sqrt;
      else if (strmatch(next, "not"   )) d->type = e_not;
      else if (strmatch(next, "pow"   )) d->type = e_pow;
      else if (strmatch(next, "random")) d->type = e_random;
      else if (strmatch(next, "hypot" )) d->type = e_hypot;
      else if (strmatch(next, "gcd"   )) d->type = e_gcd;
      else if (strmatch(next, "if"    )) d->type = e_if;
      else if (strmatch(next, "ifnot" )) d->type = e_ifnot;
      else {
          for (i=0; p->func1_names && p->func1_names[i]; i++) {
              if (strmatch(next, p->func1_names[i])) {
                  d->a.func1 = p->funcs1[i];
                  d->type = e_func1;
                  *e = d;
                  return 0;
              }
          }
  
          for (i=0; p->func2_names && p->func2_names[i]; i++) {
              if (strmatch(next, p->func2_names[i])) {
                  d->a.func2 = p->funcs2[i];
                  d->type = e_func2;
                  *e = d;
                  return 0;
              }
          }
  
          av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
          av_expr_free(d);
          return AVERROR(EINVAL);
      }
  
      *e = d;
      return 0;
  }
  
  static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
  {
      AVExpr *e = av_mallocz(sizeof(AVExpr));
      if (!e)
          return NULL;
      e->type     =type   ;
      e->value    =value  ;
      e->param[0] =p0     ;
      e->param[1] =p1     ;
      return e;
  }
  
  static int parse_pow(AVExpr **e, Parser *p, int *sign)
  {
      *sign= (*p->s == '+') - (*p->s == '-');
      p->s += *sign&1;
      return parse_primary(e, p);
  }
  
  static int parse_dB(AVExpr **e, Parser *p, int *sign)
  {
      /* do not filter out the negative sign when parsing a dB value.
         for example, -3dB is not the same as -(3dB) */
      if (*p->s == '-') {
          char *next;
          strtod(p->s, &next);
          if (next != p->s && next[0] == 'd' && next[1] == 'B') {
              *sign = 0;
              return parse_primary(e, p);
          }
      }
      return parse_pow(e, p, sign);
  }
  
  static int parse_factor(AVExpr **e, Parser *p)
  {
      int sign, sign2, ret;
      AVExpr *e0, *e1, *e2;
      if ((ret = parse_dB(&e0, p, &sign)) < 0)
          return ret;
      while(p->s[0]=='^'){
          e1 = e0;
          p->s++;
          if ((ret = parse_dB(&e2, p, &sign2)) < 0) {
              av_expr_free(e1);
              return ret;
          }
          e0 = new_eval_expr(e_pow, 1, e1, e2);
          if (!e0) {
              av_expr_free(e1);
              av_expr_free(e2);
              return AVERROR(ENOMEM);
          }
          if (e0->param[1]) e0->param[1]->value *= (sign2|1);
      }
      if (e0) e0->value *= (sign|1);
  
      *e = e0;
      return 0;
  }
  
  static int parse_term(AVExpr **e, Parser *p)
  {
      int ret;
      AVExpr *e0, *e1, *e2;
      if ((ret = parse_factor(&e0, p)) < 0)
          return ret;
      while (p->s[0]=='*' || p->s[0]=='/') {
          int c= *p->s++;
          e1 = e0;
          if ((ret = parse_factor(&e2, p)) < 0) {
              av_expr_free(e1);
              return ret;
          }
          e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
          if (!e0) {
              av_expr_free(e1);
              av_expr_free(e2);
              return AVERROR(ENOMEM);
          }
      }
      *e = e0;
      return 0;
  }
  
  static int parse_subexpr(AVExpr **e, Parser *p)
  {
      int ret;
      AVExpr *e0, *e1, *e2;
      if ((ret = parse_term(&e0, p)) < 0)
          return ret;
      while (*p->s == '+' || *p->s == '-') {
          e1 = e0;
          if ((ret = parse_term(&e2, p)) < 0) {
              av_expr_free(e1);
              return ret;
          }
          e0 = new_eval_expr(e_add, 1, e1, e2);
          if (!e0) {
              av_expr_free(e1);
              av_expr_free(e2);
              return AVERROR(ENOMEM);
          }
      };
  
      *e = e0;
      return 0;
  }
  
  static int parse_expr(AVExpr **e, Parser *p)
  {
      int ret;
      AVExpr *e0, *e1, *e2;
      if (p->stack_index <= 0) //protect against stack overflows
          return AVERROR(EINVAL);
      p->stack_index--;
  
      if ((ret = parse_subexpr(&e0, p)) < 0)
          return ret;
      while (*p->s == ';') {
          p->s++;
          e1 = e0;
          if ((ret = parse_subexpr(&e2, p)) < 0) {
              av_expr_free(e1);
              return ret;
          }
          e0 = new_eval_expr(e_last, 1, e1, e2);
          if (!e0) {
              av_expr_free(e1);
              av_expr_free(e2);
              return AVERROR(ENOMEM);
          }
      };
  
      p->stack_index++;
      *e = e0;
      return 0;
  }
  
  static int verify_expr(AVExpr *e)
  {
      if (!e) return 0;
      switch (e->type) {
          case e_value:
          case e_const: return 1;
          case e_func0:
          case e_func1:
          case e_squish:
          case e_ld:
          case e_gauss:
          case e_isnan:
          case e_isinf:
          case e_floor:
          case e_ceil:
          case e_trunc:
          case e_sqrt:
          case e_not:
          case e_random:
              return verify_expr(e->param[0]) && !e->param[1];
          case e_taylor:
              return verify_expr(e->param[0]) && verify_expr(e->param[1])
                     && (!e->param[2] || verify_expr(e->param[2]));
          default: return verify_expr(e->param[0]) && verify_expr(e->param[1]) && !e->param[2];
      }
  }
  
  int av_expr_parse(AVExpr **expr, const char *s,
                    const char * const *const_names,
                    const char * const *func1_names, double (* const *funcs1)(void *, double),
                    const char * const *func2_names, double (* const *funcs2)(void *, double, double),
                    int log_offset, void *log_ctx)
  {
      Parser p = { 0 };
      AVExpr *e = NULL;
      char *w = av_malloc(strlen(s) + 1);
      char *wp = w;
      const char *s0 = s;
      int ret = 0;
  
      if (!w)
          return AVERROR(ENOMEM);
  
      while (*s)
          if (!isspace(*s++)) *wp++ = s[-1];
      *wp++ = 0;
  
      p.class      = &class;
      p.stack_index=100;
      p.s= w;
      p.const_names = const_names;
      p.funcs1      = funcs1;
      p.func1_names = func1_names;
      p.funcs2      = funcs2;
      p.func2_names = func2_names;
      p.log_offset = log_offset;
      p.log_ctx    = log_ctx;
  
      if ((ret = parse_expr(&e, &p)) < 0)
          goto end;
      if (*p.s) {
          av_expr_free(e);
          av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
          ret = AVERROR(EINVAL);
          goto end;
      }
      if (!verify_expr(e)) {
          av_expr_free(e);
          ret = AVERROR(EINVAL);
          goto end;
      }
      e->var= av_mallocz(sizeof(double) *VARS);
      *expr = e;
  end:
      av_free(w);
      return ret;
  }
  
  double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
  {
      Parser p = { 0 };
      p.var= e->var;
  
      p.const_values = const_values;
      p.opaque     = opaque;
      return eval_expr(&p, e);
  }
  
  int av_expr_parse_and_eval(double *d, const char *s,
                             const char * const *const_names, const double *const_values,
                             const char * const *func1_names, double (* const *funcs1)(void *, double),
                             const char * const *func2_names, double (* const *funcs2)(void *, double, double),
                             void *opaque, int log_offset, void *log_ctx)
  {
      AVExpr *e = NULL;
      int ret = av_expr_parse(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
  
      if (ret < 0) {
          *d = NAN;
          return ret;
      }
      *d = av_expr_eval(e, const_values, opaque);
      av_expr_free(e);
      return isnan(*d) ? AVERROR(EINVAL) : 0;
  }
  
  #ifdef TEST
  #include <string.h>
  
  static const double const_values[] = {
      M_PI,
      M_E,
      0
  };
  
  static const char *const const_names[] = {
      "PI",
      "E",
      0
  };
  
  int main(int argc, char **argv)
  {
      int i;
      double d;
      const char *const *expr;
      static const char *const exprs[] = {
          "",
          "1;2",
          "-20",
          "-PI",
          "+PI",
          "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
          "80G/80Gi",
          "1k",
          "1Gi",
          "1gi",
          "1GiFoo",
          "1k+1k",
          "1Gi*3foo",
          "foo",
          "foo(",
          "foo()",
          "foo)",
          "sin",
          "sin(",
          "sin()",
          "sin)",
          "sin 10",
          "sin(1,2,3)",
          "sin(1 )",
          "1",
          "1foo",
          "bar + PI + E + 100f*2 + foo",
          "13k + 12f - foo(1, 2)",
          "1gi",
          "1Gi",
          "st(0, 123)",
          "st(1, 123); ld(1)",
          "lte(0, 1)",
          "lte(1, 1)",
          "lte(1, 0)",
          "lt(0, 1)",
          "lt(1, 1)",
          "gt(1, 0)",
          "gt(2, 7)",
          "gte(122, 122)",
          /* compute 1+2+...+N */
          "st(0, 1); while(lte(ld(0), 100), st(1, ld(1)+ld(0));st(0, ld(0)+1)); ld(1)",
          /* compute Fib(N) */
          "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)",
          "while(0, 10)",
          "st(0, 1); while(lte(ld(0),100), st(1, ld(1)+ld(0)); st(0, ld(0)+1))",
          "isnan(1)",
          "isnan(NAN)",
          "isnan(INF)",
          "isinf(1)",
          "isinf(NAN)",
          "isinf(INF)",
          "floor(NAN)",
          "floor(123.123)",
          "floor(-123.123)",
          "trunc(123.123)",
          "trunc(-123.123)",
          "ceil(123.123)",
          "ceil(-123.123)",
          "sqrt(1764)",
          "isnan(sqrt(-1))",
          "not(1)",
          "not(NAN)",
          "not(0)",
          "6.0206dB",
          "-3.0103dB",
          "pow(0,1.23)",
          "pow(PI,1.23)",
          "PI^1.23",
          "pow(-1,1.23)",
          "if(1, 2)",
          "ifnot(0, 23)",
          "ifnot(1, NaN) + if(0, 1)",
          "taylor(1, 1)",
          "taylor(eq(mod(ld(1),4),1)-eq(mod(ld(1),4),3), PI/2, 1)",
          "root(sin(ld(0))-1, 2)",
          "root(sin(ld(0))+6+sin(ld(0)/12)-log(ld(0)), 100)",
          "7000000B*random(0)",
          "squish(2)",
          "gauss(0.1)",
          "hypot(4,3)",
          "gcd(30,55)*min(9,1)",
          NULL
      };
  
      for (expr = exprs; *expr; expr++) {
          printf("Evaluating '%s'\n", *expr);
          av_expr_parse_and_eval(&d, *expr,
                                 const_names, const_values,
                                 NULL, NULL, NULL, NULL, NULL, 0, NULL);
          if (isnan(d))
              printf("'%s' -> nan\n\n", *expr);
          else
              printf("'%s' -> %f\n\n", *expr, d);
      }
  
      av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
                             const_names, const_values,
                             NULL, NULL, NULL, NULL, NULL, 0, NULL);
      printf("%f == 12.7\n", d);
      av_expr_parse_and_eval(&d, "80G/80Gi",
                             const_names, const_values,
                             NULL, NULL, NULL, NULL, NULL, 0, NULL);
      printf("%f == 0.931322575\n", d);
  
      if (argc > 1 && !strcmp(argv[1], "-t")) {
          for (i = 0; i < 1050; i++) {
              START_TIMER;
              av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
                                     const_names, const_values,
                                     NULL, NULL, NULL, NULL, NULL, 0, NULL);
              STOP_TIMER("av_expr_parse_and_eval");
          }
      }
  
      return 0;
  }
  #endif
  