src/strtod_noloc.c (4ef7955) - libetherpix · BlinkenArea

strtod_noloc.c

/*
 * EtherPix library
 *
 * Copyright 2010-2017 Stefan Schuermans <stefan schuermans info>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3 of the License.
 *
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <math.h>

#include <intern/strtod_noloc.h>

/**
 * \brief own version of strtod ignoring locale
 *
 * This version of strtod always expects dots in floating point numbers.
 * The reason is to be able to use the same config files for all locales.
 *
 * \param[in] nptr string containing number to parse
 * \param[out] endptr filled with pointer to
 * \return value read from the string
 */
double etp_strtod_noloc(const char *nptr, char **endptr)
{
  double sign = 1.0, value = 0.0, weight = 0.1;
  int exp_sign = 1, exp_value = 0;

/* skip whitespace */
  while (*nptr == ' ' || *nptr == '\t')
    ++nptr;

/* read optional sign */
  if (*nptr == '+') {
    sign = 1.0;
    ++nptr;
  } else if (*nptr == '-') {
    sign = -1.0;
    ++nptr;
  }

/* read digits before dot */
  while (*nptr >= '0' && *nptr <= '9') {
    value = value * 10.0 + (double)(*nptr - '0');
    ++nptr;
  }

/* read dot and digits after it */
  if (*nptr == '.') {
    ++nptr;

/* read digits after dot */
    while (*nptr >= '0' && *nptr <= '9') {
      value += weight * (double)(*nptr - '0');
      weight *= 0.1;
      ++nptr;
    }

} /* if (*nptr == '.') */

/* merge sign into value */
  value *= sign;

/* read exponent */
  if (*nptr == 'E' || *nptr == 'e') {
    ++nptr;

/* read optional sign */
    if (*nptr == '+') {
      exp_sign = 1;
      ++nptr;
    } else if (*nptr == '-') {
      exp_sign = -1;
      ++nptr;
    }

/* read digits */
    while (*nptr >= '0' && *nptr <= '9') {
      exp_value = exp_value * 10 + (int)(*nptr - '0');
      ++nptr;
    }

/* merge exponent into value */
    value *= pow(10.0, exp_sign * exp_value);

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

/* return pointer behind end */
  if (endptr)
    *endptr = (char *)nptr;

/* return value */
  return value;
}

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