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29cb9293 | 1 | /* Test whether long double value is canonical. ldbl-128ibm version. |
04277e02 | 2 | Copyright (C) 2016-2019 Free Software Foundation, Inc. |
29cb9293 JM |
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 | <http://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 | } | |
eaf5ad0b | 60 | libm_hidden_def (__iscanonicall) |