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
34static 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 */
86guint
87g_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

source code of gtk/subprojects/glib/glib/gprimes.c