sysdeps/ieee754/flt-32/s_setpayloadf_main.c

   1 /* Set NaN payload.  flt-32 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-float.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 0x7f
  27 #define PAYLOAD_DIG 22
  28 #define EXPLICIT_MANT_DIG 23
  29
  30 int
  31 FUNC (float *x, float payload)
  32 {
  33   uint32_t ix;
  34   GET_FLOAT_WORD (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 & ((1U << (BIAS + EXPLICIT_MANT_DIG - exponent)) - 1)) != 0)
  41     {
  42       SET_FLOAT_WORD (*x, 0);
  43       return 1;
  44     }
  45   if (ix != 0)
  46     {
  47       ix &= (1U << EXPLICIT_MANT_DIG) - 1;
  48       ix |= 1U << EXPLICIT_MANT_DIG;
  49       ix >>= BIAS + EXPLICIT_MANT_DIG - exponent;
  50     }
  51   ix |= 0x7f800000 | (SET_HIGH_BIT ? 0x400000 : 0);
  52   SET_FLOAT_WORD (*x, ix);
  53   return 0;
  54 }