sysdeps/ieee754/ldbl-128/s_getpayloadl.c

   1 /* Get NaN payload.  ldbl-128 version.
   2    Copyright (C) 2016-2018 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-ldouble.h>
  22 #include <stdint.h>
  23
  24 _Float128
  25 __getpayloadl (const _Float128 *x)
  26 {
  27   uint64_t hx, lx;
  28   GET_LDOUBLE_WORDS64 (hx, lx, *x);
  29   hx &= 0x7fffffffffffULL;
  30   /* Construct the representation of the return value directly, since
  31      128-bit integers may not be available.  */
  32   int lz;
  33   if (hx == 0)
  34     {
  35       if (lx == 0)
  36         return 0.0L;
  37       else
  38         lz = __builtin_clzll (lx) + 64;
  39     }
  40   else
  41     lz = __builtin_clzll (hx);
  42   int shift = lz - 15;
  43   if (shift >= 64)
  44     {
  45       hx = lx << (shift - 64);
  46       lx = 0;
  47     }
  48   else
  49     {
  50       /* 2 <= SHIFT <= 63.  */
  51       hx = (hx << shift) | (lx >> (64 - shift));
  52       lx <<= shift;
  53     }
  54   hx = (hx & 0xffffffffffffULL) | ((0x3fffULL + 127 - lz) << 48);
  55   _Float128 ret;
  56   SET_LDOUBLE_WORDS64 (ret, hx, lx);
  57   return ret;
  58 }
  59 libm_alias_ldouble (__getpayload, getpayload)