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2b778ceb | 1 | /* Copyright (C) 2005-2021 Free Software Foundation, Inc. |
fea3f995 RM |
2 | This file is part of the GNU C Library. |
3 | Contributed by Richard Henderson <rth@redhat.com>, 2005. | |
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 | |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
fea3f995 RM |
18 | |
19 | #include <stdbool.h> | |
20 | #include <math.h> | |
21 | #include <complex.h> | |
22 | ||
23 | attribute_hidden | |
24 | long double _Complex | |
25 | __multc3 (long double a, long double b, long double c, long double d) | |
26 | { | |
27 | long double ac, bd, ad, bc, x, y; | |
28 | ||
29 | ac = a * c; | |
30 | bd = b * d; | |
31 | ad = a * d; | |
32 | bc = b * c; | |
33 | ||
34 | x = ac - bd; | |
35 | y = ad + bc; | |
36 | ||
37 | if (isnan (x) && isnan (y)) | |
38 | { | |
39 | /* Recover infinities that computed as NaN + iNaN. */ | |
40 | bool recalc = 0; | |
fe8c2b33 | 41 | if (isinf (a) || isinf (b)) |
fea3f995 RM |
42 | { |
43 | /* z is infinite. "Box" the infinity and change NaNs in | |
44 | the other factor to 0. */ | |
81dca813 JM |
45 | a = copysignl (isinf (a) ? 1 : 0, a); |
46 | b = copysignl (isinf (b) ? 1 : 0, b); | |
47 | if (isnan (c)) c = copysignl (0, c); | |
48 | if (isnan (d)) d = copysignl (0, d); | |
fea3f995 RM |
49 | recalc = 1; |
50 | } | |
fe8c2b33 | 51 | if (isinf (c) || isinf (d)) |
fea3f995 RM |
52 | { |
53 | /* w is infinite. "Box" the infinity and change NaNs in | |
54 | the other factor to 0. */ | |
81dca813 JM |
55 | c = copysignl (isinf (c) ? 1 : 0, c); |
56 | d = copysignl (isinf (d) ? 1 : 0, d); | |
57 | if (isnan (a)) a = copysignl (0, a); | |
58 | if (isnan (b)) b = copysignl (0, b); | |
fea3f995 RM |
59 | recalc = 1; |
60 | } | |
61 | if (!recalc | |
fe8c2b33 WD |
62 | && (isinf (ac) || isinf (bd) |
63 | || isinf (ad) || isinf (bc))) | |
fea3f995 RM |
64 | { |
65 | /* Recover infinities from overflow by changing NaNs to 0. */ | |
81dca813 JM |
66 | if (isnan (a)) a = copysignl (0, a); |
67 | if (isnan (b)) b = copysignl (0, b); | |
68 | if (isnan (c)) c = copysignl (0, c); | |
69 | if (isnan (d)) d = copysignl (0, d); | |
fea3f995 RM |
70 | recalc = 1; |
71 | } | |
72 | if (recalc) | |
73 | { | |
74 | x = INFINITY * (a * c - b * d); | |
75 | y = INFINITY * (a * d + b * c); | |
76 | } | |
77 | } | |
78 | ||
79 | return x + I * y; | |
80 | } |