1  /* Set NaN payload.  ldbl-128ibm version.
       2     Copyright (C) 2016-2023 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 <nan-high-order-bit.h>
      22  #include <stdint.h>
      23  
      24  #define SET_HIGH_BIT (HIGH_ORDER_BIT_IS_SET_FOR_SNAN ? SIG : !SIG)
      25  #define BIAS 0x3ff
      26  #define PAYLOAD_DIG 51
      27  #define EXPLICIT_MANT_DIG 52
      28  
      29  int
      30  FUNC (long double *x, long double payload)
      31  {
      32    double hi, lo;
      33    uint64_t hx, lx;
      34  
      35    ldbl_unpack (payload, &hi, &lo);
      36    EXTRACT_WORDS64 (hx, hi);
      37    EXTRACT_WORDS64 (lx, lo);
      38    int exponent = hx >> EXPLICIT_MANT_DIG;
      39    /* Test if argument is (a) negative or too large; (b) too small,
      40       except for 0 when allowed; (c) not an integer.  All valid
      41       arguments have the low part zero.  */
      42    if ((lx & 0x7fffffffffffffffULL) != 0
      43        || exponent >= BIAS + PAYLOAD_DIG
      44        || (exponent < BIAS && !(SET_HIGH_BIT && hx == 0))
      45        || (hx & ((1ULL << (BIAS + EXPLICIT_MANT_DIG - exponent)) - 1)) != 0)
      46      {
      47        *x = 0.0L;
      48        return 1;
      49      }
      50    if (hx != 0)
      51      {
      52        hx &= (1ULL << EXPLICIT_MANT_DIG) - 1;
      53        hx |= 1ULL << EXPLICIT_MANT_DIG;
      54        hx >>= BIAS + EXPLICIT_MANT_DIG - exponent;
      55      }
      56    hx |= 0x7ff0000000000000ULL | (SET_HIGH_BIT ? 0x8000000000000ULL : 0);
      57    INSERT_WORDS64 (hi, hx);
      58    *x = ldbl_pack (hi, 0.0);
      59    return 0;
      60  }