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/* Construct a signalling NaN 'float' with a given payload.
Copyright 2024-2025 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible. */
#include <config.h>
/* Specification. */
#include <math.h>
#include <float.h>
#include <stdint.h>
#include <string.h>
#include "signed-snan.h"
int
setpayloadsigf (float *result, float payload)
{
#if FLT_MANT_DIG == 24
if (
# if defined __hppa || (defined __mips__ && !MIPS_NAN2008_FLOAT) || defined __sh__
payload >= 0.0f
# else
/* A zero payload is not allowed, because that would denote Infinity.
Cf. snan.h. */
payload > 0.0f
# endif
&& payload < 4194304.0f /* (float) (1U << (FLT_MANT_DIG - 2)) */
&& payload == (float) (int32_t) payload)
{
memory_float x = memory_positive_SNaNf ();
x.word[0] = (x.word[0] & ~((1U << (FLT_MANT_DIG - 2)) - 1))
| (int32_t) payload;
# if 0
*result = x.value;
# else
/* On 32-bit x86 processors, as well as on x86_64 processors with
CC="gcc -mfpmath=387", the evaluation of *x and *y above is done
through an 'flds' instruction, which converts a signalling NaN to
a quiet NaN. See
<https://lists.gnu.org/archive/html/bug-gnulib/2023-10/msg00060.html>
for details. Use memcpy to avoid this. */
memcpy (result, &x.value, sizeof (float));
# endif
return 0;
}
else
{
*result = 0.0f;
return -1;
}
#else
# error "Please port gnulib setpayloadsigf.c to your platform!"
#endif
}
|
