libc/stdlib/rand.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2008  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   4  *  Copyright (C) 2009  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   5  *
   6  *  This program is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20
  21 #include <stdlib.h>
  22
  23 static unsigned long next = 1;
  24
  25 static int do_rand (unsigned long *ctx)
  26 {
  27         return ((*ctx = *ctx * 1103515245 + 12345) % ((unsigned long) RAND_MAX + 1));
  28 }
  29
  30 int rand_r (unsigned int *ctx)
  31 {
  32         unsigned long val = (unsigned long) *ctx;
  33         *ctx = do_rand (&val);
  34
  35         return (int) *ctx;
  36 }
  37
  38 int rand ()
  39 {
  40         return do_rand (&next);
  41 }
  42
  43 void srand (unsigned int seed)
  44 {
  45         next = seed;
  46 }