magic.c

vxworks的tcpip协议栈源码

/* magic.c - PPP Magic Number routines */

/* Copyright 1995 Wind River Systems, Inc. */
#include "copyright_wrs.h"

/*
 * Copyright (c) 1989 Carnegie Mellon University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Carnegie Mellon University.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
modification history
--------------------
01b,16jun95,dzb  header file consolidation.
01a,21dec94,dab  VxWorks port - first WRS version.
	   +dzb  added: path for ppp header files, WRS copyright, tickLib.h.
*/

#include "vxWorks.h"
#include "tickLib.h"
#include "sys/types.h"
#include "sys/times.h"
#include "pppLib.h"

static u_long next;		/* Next value to return */

extern u_long gethostid __ARGS((void));

/*
 * magic_init - Initialize the magic number generator.
 *
 * Computes first magic number and seed for random number generator.
 * Attempts to compute a random number seed which will not repeat.
 * The current method uses the current hostid and current time.
 */
void magic_init()
{
    next = tickGet();
    srandom((int) next);
}


/*
 * magic - Returns the next magic number.
 */
u_long magic()
{
    u_long m;

    m = next;
    next = (u_long) random();
    return (m);
}