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41a359e2 | 1 | /* Return the least floating-point number greater than X. |
04277e02 | 2 | Copyright (C) 2016-2019 Free Software Foundation, Inc. |
41a359e2 RS |
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 | ||
8f5b00d3 | 19 | #include <float.h> |
41a359e2 RS |
20 | #include <math.h> |
21 | #include <math_private.h> | |
22 | #include <math_ldbl_opt.h> | |
23 | ||
24 | /* Return the least floating-point number greater than X. */ | |
25 | long double | |
26 | __nextupl (long double x) | |
27 | { | |
28 | int64_t hx, ihx, lx; | |
29 | double xhi, xlo, yhi; | |
30 | ||
31 | ldbl_unpack (x, &xhi, &xlo); | |
32 | EXTRACT_WORDS64 (hx, xhi); | |
33 | EXTRACT_WORDS64 (lx, xlo); | |
34 | ihx = hx & 0x7fffffffffffffffLL; | |
35 | ||
36 | if (ihx > 0x7ff0000000000000LL) /* x is nan. */ | |
37 | return x + x; /* Signal the nan. */ | |
38 | if (ihx == 0) | |
39 | return LDBL_TRUE_MIN; | |
40 | ||
41 | long double u; | |
42 | if ((hx == 0x7fefffffffffffffLL) && (lx == 0x7c8ffffffffffffeLL)) | |
43 | return INFINITY; | |
44 | if ((uint64_t) hx >= 0xfff0000000000000ULL) | |
45 | { | |
46 | u = -0x1.fffffffffffff7ffffffffffff8p+1023L; | |
47 | return u; | |
48 | } | |
49 | if (ihx <= 0x0360000000000000LL) | |
50 | { /* x <= LDBL_MIN. */ | |
51 | x += LDBL_TRUE_MIN; | |
52 | if (x == 0.0L) /* Handle negative LDBL_TRUE_MIN case. */ | |
53 | x = -0.0L; | |
54 | return x; | |
55 | } | |
56 | /* If the high double is an exact power of two and the low | |
57 | double is the opposite sign, then 1ulp is one less than | |
58 | what we might determine from the high double. Similarly | |
59 | if X is an exact power of two, and negative, because | |
60 | making it a little larger will result in the exponent | |
61 | decreasing by one and normalisation of the mantissa. */ | |
62 | if ((hx & 0x000fffffffffffffLL) == 0 | |
63 | && ((lx != 0 && lx != 0x8000000000000000LL && (hx ^ lx) < 0) | |
64 | || ((lx == 0 || lx == 0x8000000000000000LL) && hx < 0))) | |
65 | ihx -= 1LL << 52; | |
66 | if (ihx < (106LL << 52)) | |
67 | { /* ulp will denormal. */ | |
68 | INSERT_WORDS64 (yhi, ihx & (0x7ffLL << 52)); | |
69 | u = yhi * 0x1p-105; | |
70 | } | |
71 | else | |
72 | { | |
73 | INSERT_WORDS64 (yhi, (ihx & (0x7ffLL << 52)) - (105LL << 52)); | |
74 | u = yhi; | |
75 | } | |
76 | return x + u; | |
77 | } | |
78 | ||
79 | weak_alias (__nextupl, nextupl) |