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ffmpeg-4.2.2/compat/strtod.c 2.76 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * C99-compatible strtod() implementation
   * Copyright (c) 2012 Ronald S. Bultje <rsbultje@gmail.com>
   *
   * 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
   */
  
  #include <limits.h>
  #include <stdlib.h>
  
  #include "libavutil/avstring.h"
  #include "libavutil/mathematics.h"
  
  static const char *check_nan_suffix(const char *s)
  {
      const char *start = s;
  
      if (*s++ != '(')
          return start;
  
      while ((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
             (*s >= '0' && *s <= '9') ||  *s == '_')
          s++;
  
      return *s == ')' ? s + 1 : start;
  }
  
  #undef strtod
  double strtod(const char *, char **);
  
  double avpriv_strtod(const char *nptr, char **endptr)
  {
      const char *end;
      double res;
  
      /* Skip leading spaces */
      while (av_isspace(*nptr))
          nptr++;
  
      if (!av_strncasecmp(nptr, "infinity", 8)) {
          end = nptr + 8;
          res = INFINITY;
      } else if (!av_strncasecmp(nptr, "inf", 3)) {
          end = nptr + 3;
          res = INFINITY;
      } else if (!av_strncasecmp(nptr, "+infinity", 9)) {
          end = nptr + 9;
          res = INFINITY;
      } else if (!av_strncasecmp(nptr, "+inf", 4)) {
          end = nptr + 4;
          res = INFINITY;
      } else if (!av_strncasecmp(nptr, "-infinity", 9)) {
          end = nptr + 9;
          res = -INFINITY;
      } else if (!av_strncasecmp(nptr, "-inf", 4)) {
          end = nptr + 4;
          res = -INFINITY;
      } else if (!av_strncasecmp(nptr, "nan", 3)) {
          end = check_nan_suffix(nptr + 3);
          res = NAN;
      } else if (!av_strncasecmp(nptr, "+nan", 4) ||
                 !av_strncasecmp(nptr, "-nan", 4)) {
          end = check_nan_suffix(nptr + 4);
          res = NAN;
      } else if (!av_strncasecmp(nptr, "0x", 2) ||
                 !av_strncasecmp(nptr, "-0x", 3) ||
                 !av_strncasecmp(nptr, "+0x", 3)) {
          /* FIXME this doesn't handle exponents, non-integers (float/double)
           * and numbers too large for long long */
          res = strtoll(nptr, (char **)&end, 16);
      } else {
          res = strtod(nptr, (char **)&end);
      }
  
      if (endptr)
          *endptr = (char *)end;
  
      return res;
  }