]>
Commit | Line | Data |
---|---|---|
5b200ac2 | 1 | /* Support routines for the intrinsic power (**) operator. |
e3c063ce | 2 | Copyright (C) 2004-2013 Free Software Foundation, Inc. |
5b200ac2 FW |
3 | Contributed by Paul Brook |
4 | ||
57dea9f6 | 5 | This file is part of the GNU Fortran 95 runtime library (libgfortran). |
5b200ac2 | 6 | |
57dea9f6 TM |
7 | Libgfortran is free software; you can redistribute it and/or |
8 | modify it under the terms of the GNU General Public | |
5b200ac2 | 9 | License as published by the Free Software Foundation; either |
748086b7 | 10 | version 3 of the License, or (at your option) any later version. |
57dea9f6 TM |
11 | |
12 | Libgfortran is distributed in the hope that it will be useful, | |
5b200ac2 FW |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
57dea9f6 | 15 | GNU General Public License for more details. |
5b200ac2 | 16 | |
748086b7 JJ |
17 | Under Section 7 of GPL version 3, you are granted additional |
18 | permissions described in the GCC Runtime Library Exception, version | |
19 | 3.1, as published by the Free Software Foundation. | |
20 | ||
21 | You should have received a copy of the GNU General Public License and | |
22 | a copy of the GCC Runtime Library Exception along with this program; | |
23 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
24 | <http://www.gnu.org/licenses/>. */ | |
5b200ac2 | 25 | |
5b200ac2 FW |
26 | #include "libgfortran.h" |
27 | ||
36ae8a61 | 28 | |
7d7b8bfe | 29 | /* Use Binary Method to calculate the powi. This is not an optimal but |
5b200ac2 FW |
30 | a simple and reasonable arithmetic. See section 4.6.3, "Evaluation of |
31 | Powers" of Donald E. Knuth, "Seminumerical Algorithms", Vol. 2, "The Art | |
32 | of Computer Programming", 3rd Edition, 1998. */ | |
33 | ||
644cb69f FXC |
34 | #if defined (HAVE_GFC_COMPLEX_8) && defined (HAVE_GFC_INTEGER_8) |
35 | ||
7d7b8bfe RH |
36 | GFC_COMPLEX_8 pow_c8_i8 (GFC_COMPLEX_8 a, GFC_INTEGER_8 b); |
37 | export_proto(pow_c8_i8); | |
38 | ||
5b200ac2 | 39 | GFC_COMPLEX_8 |
7d7b8bfe | 40 | pow_c8_i8 (GFC_COMPLEX_8 a, GFC_INTEGER_8 b) |
5b200ac2 FW |
41 | { |
42 | GFC_COMPLEX_8 pow, x; | |
3d1f465a TK |
43 | GFC_INTEGER_8 n; |
44 | GFC_UINTEGER_8 u; | |
5b200ac2 FW |
45 | |
46 | n = b; | |
47 | x = a; | |
48 | pow = 1; | |
49 | if (n != 0) | |
50 | { | |
51 | if (n < 0) | |
52 | { | |
53 | ||
3d1f465a | 54 | u = -n; |
5b200ac2 FW |
55 | x = pow / x; |
56 | } | |
3d1f465a TK |
57 | else |
58 | { | |
59 | u = n; | |
60 | } | |
5b200ac2 FW |
61 | for (;;) |
62 | { | |
63 | if (u & 1) | |
64 | pow *= x; | |
65 | u >>= 1; | |
66 | if (u) | |
67 | x *= x; | |
68 | else | |
69 | break; | |
70 | } | |
71 | } | |
72 | return pow; | |
73 | } | |
644cb69f FXC |
74 | |
75 | #endif |