glibc/sysdeps/ieee754/dbl-64/s_setpayload_main.c

55 lines
1.8 KiB
C

/* Set NaN payload.
Copyright (C) 2016-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library 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 2.1 of the License, or (at your option) any later version.
The GNU C Library 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 the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <math.h>
#include <math_private.h>
#include <libm-alias-double.h>
#include <nan-high-order-bit.h>
#include <stdint.h>
#define SET_HIGH_BIT (HIGH_ORDER_BIT_IS_SET_FOR_SNAN ? SIG : !SIG)
#define BIAS 0x3ff
#define PAYLOAD_DIG 51
#define EXPLICIT_MANT_DIG 52
int
FUNC (double *x, double payload)
{
uint64_t ix;
EXTRACT_WORDS64 (ix, payload);
int exponent = ix >> EXPLICIT_MANT_DIG;
/* Test if argument is (a) negative or too large; (b) too small,
except for 0 when allowed; (c) not an integer. */
if (exponent >= BIAS + PAYLOAD_DIG
|| (exponent < BIAS && !(SET_HIGH_BIT && ix == 0))
|| (ix & ((1ULL << (BIAS + EXPLICIT_MANT_DIG - exponent)) - 1)) != 0)
{
INSERT_WORDS64 (*x, 0);
return 1;
}
if (ix != 0)
{
ix &= (1ULL << EXPLICIT_MANT_DIG) - 1;
ix |= 1ULL << EXPLICIT_MANT_DIG;
ix >>= BIAS + EXPLICIT_MANT_DIG - exponent;
}
ix |= 0x7ff0000000000000ULL | (SET_HIGH_BIT ? 0x8000000000000ULL : 0);
INSERT_WORDS64 (*x, ix);
return 0;
}