sysdeps/ieee754/ldbl-128/s_getpayloadl.c

   1 /* Get NaN payload.  ldbl-128 version.
   2    Copyright (C) 2016-2024 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    <https://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   if ((hx & 0x7fff000000000000ULL) != 0x7fff000000000000ULL
  30       || ((hx & 0xffffffffffffULL) | lx) == 0)
  31     return -1;
  32   hx &= 0x7fffffffffffULL;
  33   /* Construct the representation of the return value directly, since
  34      128-bit integers may not be available.  */
  35   int lz;
  36   if (hx == 0)
  37     {
  38       if (lx == 0)
  39         return 0.0L;
  40       else
  41         lz = __builtin_clzll (lx) + 64;
  42     }
  43   else
  44     lz = __builtin_clzll (hx);
  45   int shift = lz - 15;
  46   if (shift >= 64)
  47     {
  48       hx = lx << (shift - 64);
  49       lx = 0;
  50     }
  51   else
  52     {
  53       /* 2 <= SHIFT <= 63.  */
  54       hx = (hx << shift) | (lx >> (64 - shift));
  55       lx <<= shift;
  56     }
  57   hx = (hx & 0xffffffffffffULL) | ((0x3fffULL + 127 - lz) << 48);
  58   _Float128 ret;
  59   SET_LDOUBLE_WORDS64 (ret, hx, lx);
  60   return ret;
  61 }
  62 libm_alias_ldouble (__getpayload, getpayload)