X-Git-Url: https://git.saurik.com/apple/libc.git/blobdiff_plain/3b2a1fe8d3d02703ddca1b0ead469074d4e47820..5b2abdfbf4211b6592cdd02b9507555a0ecbb04b:/stdlib/rand.c

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+/*-
+ * 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. 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.
+ *
+ * Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>.
+ *
+ * $FreeBSD: src/lib/libc/stdlib/rand.c,v 1.2.2.1 2001/03/05 11:33:57 obrien Exp $
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)rand.c	8.1 (Berkeley) 6/14/93";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+#include <stdlib.h>
+
+#ifdef TEST
+#include <stdio.h>
+#endif /* TEST */
+
+static int
+do_rand(unsigned long *ctx)
+{
+	return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1));
+}
+
+
+int
+rand_r(unsigned int *ctx)
+{
+	u_long val = (u_long) *ctx;
+	*ctx = do_rand(&val);
+	return (int) *ctx;
+}
+
+
+static u_long next = 1;
+
+int
+rand()
+{
+	return do_rand(&next);
+}
+
+void
+srand(seed)
+u_int seed;
+{
+	next = seed;
+}
+
+#ifdef TEST
+
+main()
+{
+    int i;
+    unsigned myseed;
+
+    printf("seeding rand with 0x19610910: \n");
+    srand(0x19610910);
+
+    printf("generating three pseudo-random numbers:\n");
+    for (i = 0; i < 3; i++)
+    {
+	printf("next random number = %d\n", rand());
+    }
+
+    printf("generating the same sequence with rand_r:\n");
+    myseed = 0x19610910;
+    for (i = 0; i < 3; i++)
+    {
+	printf("next random number = %d\n", rand_r(&myseed));
+    }
+
+    return 0;
+}
+
+#endif /* TEST */
+