Add random.c

Author: robertinant

hardware/msp430/cores/msp430/random.c

@@ -0,0 +1,90 @@
+/*-
+ * Copyright (c) 1990, 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. 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.
+ *
+ * Posix rand_r function added May 1999 by Wes Peters <[email protected]>.
+ *
+ * $Id$
+ */
+
+/*
+ * From:
+static char sccsid[] = "@(#)rand.c	8.1 (Berkeley) 6/14/93";
+*/
+#ifndef RANDOM_MAX
+#define RANDOM_MAX 0x7FFFFFFF
+#endif
+
+#include <stdlib.h>
+
+static long
+do_random(unsigned long *ctx)
+{
+	/*
+	 * Compute x = (7^5 * x) mod (2^31 - 1)
+	 * wihout overflowing 31 bits:
+	 *      (2^31 - 1) = 127773 * (7^5) + 2836
+	 * 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.
+	 */
+	long hi, lo, x;
+
+	x = *ctx;
+	/* Can't be initialized with 0, so use another value. */
+	if (x == 0)
+		x = 123459876L;
+	hi = x / 127773L;
+	lo = x % 127773L;
+	x = 16807L * lo - 2836L * hi;
+	if (x < 0)
+		x += 0x7fffffffL;
+	return ((*ctx = x) % ((unsigned long)RANDOM_MAX + 1));
+}
+
+
+long
+random_r(unsigned long *ctx)
+{
+	return do_random(ctx);
+}
+
+
+static unsigned long next = 1;
+
+long
+random(void)
+{
+	return do_random(&next);
+}
+
+void
+srandom(unsigned long seed)
+{
+	next = seed;
+}
+