sysdeps/ieee754/dbl-64/s_totalorder.c

   1 /* Total order operation.  dbl-64 version.
   2    Copyright (C) 2016 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 <stdint.h>
  22
  23 int
  24 totalorder (double x, double y)
  25 {
  26   int32_t hx, hy;
  27   uint32_t lx, ly;
  28   EXTRACT_WORDS (hx, lx, x);
  29   EXTRACT_WORDS (hy, ly, y);
  30 #ifdef HIGH_ORDER_BIT_IS_SET_FOR_SNAN
  31   uint32_t uhx = hx & 0x7fffffff, uhy = hy & 0x7fffffff;
  32   /* For the preferred quiet NaN convention, this operation is a
  33      comparison of the representations of the arguments interpreted as
  34      sign-magnitude integers.  If both arguments are NaNs, invert the
  35      quiet/signaling bit so comparing that way works.  */
  36   if ((uhx > 0x7ff00000 || (uhx == 0x7ff00000 && lx != 0))
  37       && (uhy > 0x7ff00000 || (uhy == 0x7ff00000 && ly != 0)))
  38     {
  39       hx ^= 0x00080000;
  40       hy ^= 0x00080000;
  41     }
  42 #endif
  43   uint32_t hx_sign = hx >> 31;
  44   uint32_t hy_sign = hy >> 31;
  45   hx ^= hx_sign >> 1;
  46   lx ^= hx_sign;
  47   hy ^= hy_sign >> 1;
  48   ly ^= hy_sign;
  49   return hx < hy || (hx == hy && lx <= ly);
  50 }
  51 #ifdef NO_LONG_DOUBLE
  52 weak_alias (totalorder, totalorderl)
  53 #endif