1  /* Set NaN payload.  ldbl-96 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 <libm-alias-ldouble.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 0x3fff
      27  #define PAYLOAD_DIG 62
      28  #define EXPLICIT_MANT_DIG 63
      29  
      30  int
      31  FUNC (long double *x, long double payload)
      32  {
      33    uint32_t hx, lx;
      34    uint16_t exponent;
      35    GET_LDOUBLE_WORDS (exponent, hx, lx, payload);
      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
      40  			       && exponent == 0 && hx == 0 && lx == 0)))
      41      {
      42        SET_LDOUBLE_WORDS (*x, 0, 0, 0);
      43        return 1;
      44      }
      45    int shift = BIAS + EXPLICIT_MANT_DIG - exponent;
      46    if (shift < 32
      47        ? (lx & ((1U << shift) - 1)) != 0
      48        : (lx != 0 || (hx & ((1U << (shift - 32)) - 1)) != 0))
      49      {
      50        SET_LDOUBLE_WORDS (*x, 0, 0, 0);
      51        return 1;
      52      }
      53    if (exponent != 0)
      54      {
      55        if (shift >= 32)
      56  	{
      57  	  lx = hx >> (shift - 32);
      58  	  hx = 0;
      59  	}
      60        else if (shift != 0)
      61  	{
      62  	  lx = (lx >> shift) | (hx << (32 - shift));
      63  	  hx >>= shift;
      64  	}
      65      }
      66    hx |= 0x80000000 | (SET_HIGH_BIT ? 0x40000000 : 0);
      67    SET_LDOUBLE_WORDS (*x, 0x7fff, hx, lx);
      68    return 0;
      69  }