2 * magic.c - PPP Magic Number routines.
4 * Copyright (c) 1989 Carnegie Mellon University.
7 * Redistribution and use in source and binary forms are permitted
8 * provided that the above copyright notice and this paragraph are
9 * duplicated in all such forms and that any documentation,
10 * advertising materials, and other materials related to such
11 * distribution and use acknowledge that the software was developed
12 * by Carnegie Mellon University. The name of the
13 * University may not be used to endorse or promote products derived
14 * from this software without specific prior written permission.
15 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
17 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
21 static char rcsid[] = "$Id: magic.c,v 1.5 1995/06/06 01:52:25 paulus Exp $";
25 #include <sys/types.h>
31 static u_int32_t next; /* Next value to return */
33 extern int gethostid __P((void));
34 extern long mrand48 __P((void));
35 extern void srand48 __P((long));
39 * magic_init - Initialize the magic number generator.
41 * Attempts to compute a random number seed which will not repeat.
42 * The current method uses the current hostid, current process ID
43 * and current time, currently.
51 gettimeofday(&t, NULL);
52 seed = gethostid() ^ t.tv_sec ^ t.tv_usec ^ getpid();
57 * magic - Returns the next magic number.
62 return (u_int32_t) mrand48();
67 * Substitute procedures for those systems which don't have
74 return (double)random() / (double)0x7fffffffL; /* 2**31-1 */
87 srandom((int)seedval);