73 lines
2.5 KiB
C
73 lines
2.5 KiB
C
/*-
|
|
* Copyright (c) 1992, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)random.c 8.1 (Berkeley) 6/10/93
|
|
* $Id$
|
|
*/
|
|
|
|
#include <sys/libkern.h>
|
|
|
|
static u_long randseed = 1;
|
|
|
|
void
|
|
srandom(seed)
|
|
u_long seed;
|
|
{
|
|
randseed = seed;
|
|
}
|
|
|
|
/*
|
|
* Pseudo-random number generator for randomizing the profiling clock,
|
|
* and whatever else we might use it for. The result is uniform on
|
|
* [0, 2^31 - 1].
|
|
*/
|
|
u_long
|
|
random()
|
|
{
|
|
register long x, hi, lo, t;
|
|
|
|
/*
|
|
* Compute x[n + 1] = (7^5 * x[n]) mod (2^31 - 1).
|
|
* From "Random number generators: good ones are hard to find",
|
|
* Park and Miller, Communications of the ACM, vol. 31, no. 10,
|
|
* October 1988, p. 1195.
|
|
*/
|
|
x = randseed;
|
|
hi = x / 127773;
|
|
lo = x % 127773;
|
|
t = 16807 * lo - 2836 * hi;
|
|
if (t <= 0)
|
|
t += 0x7fffffff;
|
|
randseed = t;
|
|
return (t);
|
|
}
|