1 | /* GLIB - Library of useful routines for C programming |
2 | * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald |
3 | * |
4 | * This library is free software; you can redistribute it and/or |
5 | * modify it under the terms of the GNU Lesser General Public |
6 | * License as published by the Free Software Foundation; either |
7 | * version 2.1 of the License, or (at your option) any later version. |
8 | * |
9 | * This library is distributed in the hope that it will be useful, |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | * Lesser General Public License for more details. |
13 | * |
14 | * You should have received a copy of the GNU Lesser General Public |
15 | * License along with this library; if not, see <http://www.gnu.org/licenses/>. |
16 | */ |
17 | |
18 | /* |
19 | * Modified by the GLib Team and others 1997-2000. See the AUTHORS |
20 | * file for a list of people on the GLib Team. See the ChangeLog |
21 | * files for a list of changes. These files are distributed with |
22 | * GLib at ftp://ftp.gtk.org/pub/gtk/. |
23 | */ |
24 | |
25 | /* |
26 | * MT safe |
27 | */ |
28 | |
29 | #include "config.h" |
30 | |
31 | #include "gprimes.h" |
32 | |
33 | |
34 | static const guint g_primes[] = |
35 | { |
36 | 11, |
37 | 19, |
38 | 37, |
39 | 73, |
40 | 109, |
41 | 163, |
42 | 251, |
43 | 367, |
44 | 557, |
45 | 823, |
46 | 1237, |
47 | 1861, |
48 | 2777, |
49 | 4177, |
50 | 6247, |
51 | 9371, |
52 | 14057, |
53 | 21089, |
54 | 31627, |
55 | 47431, |
56 | 71143, |
57 | 106721, |
58 | 160073, |
59 | 240101, |
60 | 360163, |
61 | 540217, |
62 | 810343, |
63 | 1215497, |
64 | 1823231, |
65 | 2734867, |
66 | 4102283, |
67 | 6153409, |
68 | 9230113, |
69 | 13845163, |
70 | }; |
71 | |
72 | /** |
73 | * g_spaced_primes_closest: |
74 | * @num: a #guint |
75 | * |
76 | * Gets the smallest prime number from a built-in array of primes which |
77 | * is larger than @num. This is used within GLib to calculate the optimum |
78 | * size of a #GHashTable. |
79 | * |
80 | * The built-in array of primes ranges from 11 to 13845163 such that |
81 | * each prime is approximately 1.5-2 times the previous prime. |
82 | * |
83 | * Returns: the smallest prime number from a built-in array of primes |
84 | * which is larger than @num |
85 | */ |
86 | guint |
87 | g_spaced_primes_closest (guint num) |
88 | { |
89 | gsize i; |
90 | |
91 | for (i = 0; i < G_N_ELEMENTS (g_primes); i++) |
92 | if (g_primes[i] > num) |
93 | return g_primes[i]; |
94 | |
95 | return g_primes[G_N_ELEMENTS (g_primes) - 1]; |
96 | } |
97 | |