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/*

 * strtod.c - This file is part of the libc-8086 package for ELKS,

 * Copyright (C) 1995, 1996 Nat Friedman <ndf@linux.mit.edu>.

 *

 *  This library is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU Library General Public

 *  License as published by the Free Software Foundation; either

 *  version 2 of the License, or (at your option) any later version.

 *

 *  This library 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

 *  Library General Public License for more details.

 *

 *  You should have received a copy of the GNU Library General Public

 *  License along with this library; if not, write to the Free

 *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 *

 */

#include <stdlib.h>

#include <ctype.h>

float

strtod(const char *nptr, char ** endptr)

{

  unsigned short negative;

  float number;

  float fp_part;

  int exponent;

  unsigned short exp_negative;

  /* advance beyond any leading whitespace */

  while (isspace(*nptr))

    nptr++;

  /* check for optional '+' or '-' */

  negative=0;

  if (*nptr=='-')

    {

      negative=1;

      nptr++;

    }

  else

    if (*nptr=='+')

      nptr++;

  number=0;

  while (isdigit(*nptr))

    {

      number=number*10+(*nptr-'0');

      nptr++;

    }

  if (*nptr=='.')

    {

      nptr++;

      fp_part=0;

      while (isdigit(*nptr))

        {

          fp_part=fp_part/10.0 + (*nptr-'0')/10.0;

          nptr++;

        }

      number+=fp_part;

    }

  if (*nptr=='e' || *nptr=='E')

    {

      nptr++;

      exp_negative=0;

      if (*nptr=='-')

        {

          exp_negative=1;

          nptr++;

        }

      else

        if (*nptr=='+')

          nptr++;

      exponent=0;

      while (isdigit(*nptr))

        {

          exponent=exponent*10+(*nptr-'0');

          exponent++;

        }

    }

  while (exponent)

    {

      if (exp_negative)

        number/=10;

      else

        number*=10;

      exponent--;

    }

  return (negative ? -number:number);

}