1  /* Convert string for NaN payload to corresponding NaN.
       2     Copyright (C) 1997-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <ieee754.h>
      20  #include <locale.h>
      21  #include <math.h>
      22  #include <stdlib.h>
      23  #include <wchar.h>
      24  
      25  
      26  /* If STR starts with an optional n-char-sequence as defined by ISO C
      27     (a sequence of ASCII letters, digits and underscores), followed by
      28     ENDC, return a NaN whose payload is set based on STR.  Otherwise,
      29     return a default NAN.  If ENDPTR is not NULL, set *ENDPTR to point
      30     to the character after the initial n-char-sequence.  */
      31  
      32  FLOAT
      33  STRTOD_NAN (const STRING_TYPE *str, STRING_TYPE **endptr, STRING_TYPE endc)
      34  {
      35    const STRING_TYPE *cp = str;
      36  
      37    while ((*cp >= L_('0') && *cp <= L_('9'))
      38  	 || (*cp >= L_('A') && *cp <= L_('Z'))
      39  	 || (*cp >= L_('a') && *cp <= L_('z'))
      40  	 || *cp == L_('_'))
      41      ++cp;
      42  
      43    FLOAT retval = NAN;
      44    if (*cp != endc)
      45      goto out;
      46  
      47    /* This is a system-dependent way to specify the bitmask used for
      48       the NaN.  We expect it to be a number which is put in the
      49       mantissa of the number.  */
      50    STRING_TYPE *endp;
      51    unsigned long long int mant;
      52  
      53    mant = STRTOULL (str, &endp, 0);
      54    if (endp == cp)
      55      SET_NAN_PAYLOAD (retval, mant);
      56  
      57   out:
      58    if (endptr != NULL)
      59      *endptr = (STRING_TYPE *) cp;
      60    return retval;
      61  }
      62  libc_hidden_def (STRTOD_NAN)