| /*- |
| * 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. |
| * 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 |
| */ |
| |
| #include <sys/bsd_cdefs.h> |
| //__FBSDID("$FreeBSD$"); |
| |
| #include <sys/bsd_libkern.h> |
| |
| #define NSHUFF 50 /* to drop some "seed -> 1st value" linearity */ |
| |
| static u_long randseed = 937186357; /* after srandom(1), NSHUFF counted */ |
| |
| void |
| srandom(seed) |
| u_long seed; |
| { |
| int i; |
| |
| randseed = seed; |
| for (i = 0; i < NSHUFF; i++) |
| (void)random(); |
| } |
| |
| /* |
| * 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. |
| */ |
| /* Can't be initialized with 0, so use another value. */ |
| if ((x = randseed) == 0) |
| x = 123459876; |
| hi = x / 127773; |
| lo = x % 127773; |
| t = 16807 * lo - 2836 * hi; |
| if (t < 0) |
| t += 0x7fffffff; |
| randseed = t; |
| return (t); |
| } |
