1  /* Set NaN payload.
       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 <libm-alias-double.h>
      22  #include <nan-high-order-bit.h>
      23  #include <stdint.h>
      24  
      25  #define SET_HIGH_BIT (HIGH_ORDER_BIT_IS_SET_FOR_SNAN ? SIG : !SIG)
      26  #define BIAS 0x3ff
      27  #define PAYLOAD_DIG 51
      28  #define EXPLICIT_MANT_DIG 52
      29  
      30  int
      31  FUNC (double *x, double payload)
      32  {
      33    uint64_t ix;
      34    EXTRACT_WORDS64 (ix, payload);
      35    int exponent = ix >> EXPLICIT_MANT_DIG;
      36    /* Test if argument is (a) negative or too large; (b) too small,
      37       except for 0 when allowed; (c) not an integer.  */
      38    if (exponent >= BIAS + PAYLOAD_DIG
      39        || (exponent < BIAS && !(SET_HIGH_BIT && ix == 0))
      40        || (ix & ((1ULL << (BIAS + EXPLICIT_MANT_DIG - exponent)) - 1)) != 0)
      41      {
      42        INSERT_WORDS64 (*x, 0);
      43        return 1;
      44      }
      45    if (ix != 0)
      46      {
      47        ix &= (1ULL << EXPLICIT_MANT_DIG) - 1;
      48        ix |= 1ULL << EXPLICIT_MANT_DIG;
      49        ix >>= BIAS + EXPLICIT_MANT_DIG - exponent;
      50      }
      51    ix |= 0x7ff0000000000000ULL | (SET_HIGH_BIT ? 0x8000000000000ULL : 0);
      52    INSERT_WORDS64 (*x, ix);
      53    return 0;
      54  }