sysdeps/ieee754/dbl-64/s_nextup.c

   1 /* Return the least floating-point number greater than X.
   2    Copyright (C) 2016-2017 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <math.h>
  20 #include <math_private.h>
  21 #include <libm-alias-double.h>
  22
  23 /* Return the least floating-point number greater than X.  */
  24 double
  25 __nextup (double x)
  26 {
  27   int32_t hx, ix;
  28   uint32_t lx;
  29
  30   EXTRACT_WORDS (hx, lx, x);
  31   ix = hx & 0x7fffffff;
  32
  33   if (((ix >= 0x7ff00000) && ((ix - 0x7ff00000) | lx) != 0))  /* x is nan.  */
  34     return x + x;
  35   if ((ix | lx) == 0)
  36     return DBL_TRUE_MIN;
  37   if (hx >= 0)
  38     {                           /* x > 0.  */
  39       if (isinf (x))
  40         return x;
  41       lx += 1;
  42       if (lx == 0)
  43         hx += 1;
  44     }
  45   else
  46     {                           /* x < 0.  */
  47       if (lx == 0)
  48         hx -= 1;
  49       lx -= 1;
  50     }
  51   INSERT_WORDS (x, hx, lx);
  52   return x;
  53 }
  54
  55 libm_alias_double (__nextup, nextup)