lib/copysignl.c

   1 /* Copy sign into another 'long double' number.
   2    Copyright (C) 2011-2024 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation, either version 3 of the
   7    License, or (at your option) any later version.
   8
   9    This file is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <math.h>
  21
  22 #if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
  23
  24 long double
  25 copysignl (long double x, long double y)
  26 {
  27   return copysign (x, y);
  28 }
  29
  30 #else
  31
  32 # if defined __hpux && !defined __GNUC__
  33
  34 #  include <float.h>
  35
  36 /* HP cc on HP-UX 10.20 has a bug with the constant expression -0.0L.  */
  37 static long double
  38 compute_minus_zerol (void)
  39 {
  40   return -LDBL_MIN * LDBL_MIN;
  41 }
  42 #  define minus_zerol compute_minus_zerol ()
  43
  44 /* HP cc on HP-UX 11 has a bug: When x is a positive zero, - x comes out
  45    as a positive zero, rather than as a minus zero.  Work around it.  */
  46 static long double
  47 unary_minus (long double x)
  48 {
  49   if (x == 0.0L)
  50     {
  51       if (signbit (x))
  52         return 0.0L;
  53       else
  54         return minus_zerol;
  55     }
  56   else
  57     return - x;
  58 }
  59
  60 # endif
  61
  62 long double
  63 copysignl (long double x, long double y)
  64 {
  65 # if defined __hpux && !defined __GNUC__
  66   return (signbit (x) != signbit (y) ? unary_minus (x) : x);
  67 # else
  68   return (signbit (x) != signbit (y) ? - x : x);
  69 # endif
  70 }
  71
  72 #endif