sysdeps/ieee754/ldbl-96/s_iscanonicall.c

   1 /* Test whether long double value is canonical.  ldbl-96 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 <float.h>
  20 #include <math.h>
  21 #include <math_private.h>
  22 #include <stdbool.h>
  23 #include <stdint.h>
  24
  25 int
  26 __iscanonicall (long double x)
  27 {
  28   uint32_t se, i0, i1 __attribute__ ((unused));
  29
  30   GET_LDOUBLE_WORDS (se, i0, i1, x);
  31   int32_t ix = se & 0x7fff;
  32   bool mant_high = (i0 & 0x80000000) != 0;
  33
  34   if (LDBL_MIN_EXP == -16381)
  35     /* Intel variant: the high mantissa bit should have a value
  36        determined by the exponent.  */
  37     return ix > 0 ? mant_high : !mant_high;
  38   else
  39     /* M68K variant: both values of the high bit are valid for the
  40        greatest and smallest exponents, while other exponents require
  41        the high bit to be set.  */
  42     return ix == 0 || ix == 0x7fff || mant_high;
  43 }
  44 libm_hidden_def (__iscanonicall)