sysdeps/ieee754/dbl-64/s_totalorder.c

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