1/*
2  PIM for Quagga
3  Copyright (C) 2008  Everton da Silva Marques
4
5  This program is free software; you can redistribute it and/or modify
6  it under the terms of the GNU General Public License as published by
7  the Free Software Foundation; either version 2 of the License, or
8  (at your option) any later version.
9
10  This program is distributed in the hope that it will be useful, but
11  WITHOUT ANY WARRANTY; without even the implied warranty of
12  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13  General Public License for more details.
14
15  You should have received a copy of the GNU General Public License
16  along with this program; see the file COPYING; if not, write to the
17  Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
18  MA 02110-1301 USA
19
20  $QuaggaId: $Format:%an, %ai, %h$ $
21*/
22
23#include "pim_rand.h"
24#include "pim_time.h"
25
26/* Quick and dirty random number generator from NUMERICAL RECIPES IN C:
27   THE ART OF SCIENTIFIC COMPUTING (ISBN 0-521-43108-5). */
28/* BEWARE: '_qseed_' is assigned! */
29#define QRANDOM(_qseed_)  ((_qseed_) = (((_qseed_) * 1664525L) + 1013904223L))
30
31static long qpim_rand_seed;
32
33void pim_rand_init()
34{
35  qpim_rand_seed = pim_time_monotonic_sec() ^ getpid();
36}
37
38long pim_rand()
39{
40  return QRANDOM(qpim_rand_seed);
41}
42
43int pim_rand_next(int min, int max)
44{
45  long rand;
46
47  assert(min <= max);
48
49  /* FIXME better random generator ? */
50
51  rand = QRANDOM(qpim_rand_seed);
52  if (rand < 0)
53    rand = -rand;
54  rand = rand % (1 + max - min) + min;
55
56  assert(rand >= min);
57  assert(rand <= max);
58
59  return rand;
60}
61