glib/gprimes.c

   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 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, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 /*
  21  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  22  * file for a list of people on the GLib Team.  See the ChangeLog
  23  * files for a list of changes.  These files are distributed with
  24  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  25  */
  26
  27 /*
  28  * MT safe
  29  */
  30
  31 #include "config.h"
  32
  33 #include "glib.h"
  34
  35
  36 static const guint g_primes[] =
  37 {
  38   11,
  39   19,
  40   37,
  41   73,
  42   109,
  43   163,
  44   251,
  45   367,
  46   557,
  47   823,
  48   1237,
  49   1861,
  50   2777,
  51   4177,
  52   6247,
  53   9371,
  54   14057,
  55   21089,
  56   31627,
  57   47431,
  58   71143,
  59   106721,
  60   160073,
  61   240101,
  62   360163,
  63   540217,
  64   810343,
  65   1215497,
  66   1823231,
  67   2734867,
  68   4102283,
  69   6153409,
  70   9230113,
  71   13845163,
  72 };
  73
  74 static const guint g_nprimes = sizeof (g_primes) / sizeof (g_primes[0]);
  75
  76 guint
  77 g_spaced_primes_closest (guint num)
  78 {
  79   gint i;
  80
  81   for (i = 0; i < g_nprimes; i++)
  82     if (g_primes[i] > num)
  83       return g_primes[i];
  84
  85   return g_primes[g_nprimes - 1];
  86 }