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authormsmith <msmith@FreeBSD.org>1998-08-20 08:19:55 +0000
committermsmith <msmith@FreeBSD.org>1998-08-20 08:19:55 +0000
commit335c4be5b17816baac6b70d4d0b3132925de858d (patch)
tree93349031c3cbd63fd287516f83a63841b7e8105b /lib/libstand/random.c
parent0ad6b3714378015da93827e12e95fa078a91ef12 (diff)
downloadFreeBSD-src-335c4be5b17816baac6b70d4d0b3132925de858d.zip
FreeBSD-src-335c4be5b17816baac6b70d4d0b3132925de858d.tar.gz
This is libstand; a support library for standalone executables (eg. bootstrap
modules). Obtained from: NetBSD, with some architectural changes and many additions.
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diff --git a/lib/libstand/random.c b/lib/libstand/random.c
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+/*-
+ * 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: random.c,v 1.6 1997/02/22 09:39:59 peter Exp $
+ */
+
+#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);
+}
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