1 | /* Test whether long double value is canonical. 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 <stdint.h> |
22 | |
23 | int |
24 | __iscanonicall (long double x) |
25 | { |
26 | double xhi, xlo; |
27 | uint64_t hx, lx; |
28 | |
29 | ldbl_unpack (x, &xhi, &xlo); |
30 | EXTRACT_WORDS64 (hx, xhi); |
31 | EXTRACT_WORDS64 (lx, xlo); |
32 | int64_t ix = hx & 0x7fffffffffffffffULL; |
33 | int64_t iy = lx & 0x7fffffffffffffffULL; |
34 | int hexp = (ix & 0x7ff0000000000000LL) >> 52; |
35 | int lexp = (iy & 0x7ff0000000000000LL) >> 52; |
36 | |
37 | if (iy == 0) |
38 | /* Low part 0 is always OK. */ |
39 | return 1; |
40 | |
41 | if (hexp == 0x7ff) |
42 | /* If a NaN, the low part does not matter. If an infinity, the |
43 | low part must be 0, in which case we have already returned. */ |
44 | return ix != 0x7ff0000000000000LL; |
45 | |
46 | /* The high part is finite and the low part is nonzero. There must |
47 | be sufficient difference between the exponents. */ |
48 | bool low_p2; |
49 | if (lexp == 0) |
50 | { |
51 | /* Adjust the exponent for subnormal low part. */ |
52 | lexp = 12 - __builtin_clzll (iy); |
53 | low_p2 = iy == (1LL << (51 + lexp)); |
54 | } |
55 | else |
56 | low_p2 = (iy & 0xfffffffffffffLL) == 0; |
57 | int expdiff = hexp - lexp; |
58 | return expdiff > 53 || (expdiff == 53 && low_p2 && (ix & 1) == 0); |
59 | } |
60 | libm_hidden_def (__iscanonicall) |
61 | |