1/* Set NaN payload. ldbl-128ibm version.
2 Copyright (C) 2016-2022 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 <nan-high-order-bit.h>
22#include <stdint.h>
23
24#define SET_HIGH_BIT (HIGH_ORDER_BIT_IS_SET_FOR_SNAN ? SIG : !SIG)
25#define BIAS 0x3ff
26#define PAYLOAD_DIG 51
27#define EXPLICIT_MANT_DIG 52
28
29int
30FUNC (long double *x, long double payload)
31{
32 double hi, lo;
33 uint64_t hx, lx;
34
35 ldbl_unpack (payload, &hi, &lo);
36 EXTRACT_WORDS64 (hx, hi);
37 EXTRACT_WORDS64 (lx, lo);
38 int exponent = hx >> EXPLICIT_MANT_DIG;
39 /* Test if argument is (a) negative or too large; (b) too small,
40 except for 0 when allowed; (c) not an integer. All valid
41 arguments have the low part zero. */
42 if ((lx & 0x7fffffffffffffffULL) != 0
43 || exponent >= BIAS + PAYLOAD_DIG
44 || (exponent < BIAS && !(SET_HIGH_BIT && hx == 0))
45 || (hx & ((1ULL << (BIAS + EXPLICIT_MANT_DIG - exponent)) - 1)) != 0)
46 {
47 *x = 0.0L;
48 return 1;
49 }
50 if (hx != 0)
51 {
52 hx &= (1ULL << EXPLICIT_MANT_DIG) - 1;
53 hx |= 1ULL << EXPLICIT_MANT_DIG;
54 hx >>= BIAS + EXPLICIT_MANT_DIG - exponent;
55 }
56 hx |= 0x7ff0000000000000ULL | (SET_HIGH_BIT ? 0x8000000000000ULL : 0);
57 INSERT_WORDS64 (hi, hx);
58 *x = ldbl_pack (hi, 0.0);
59 return 0;
60}
61

source code of glibc/sysdeps/ieee754/ldbl-128ibm/s_setpayloadl_main.c