summaryrefslogtreecommitdiffstats
path: root/lib/libc/stdlib/rand.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/libc/stdlib/rand.c')
-rw-r--r--lib/libc/stdlib/rand.c105
1 files changed, 105 insertions, 0 deletions
diff --git a/lib/libc/stdlib/rand.c b/lib/libc/stdlib/rand.c
new file mode 100644
index 0000000..94f6b50
--- /dev/null
+++ b/lib/libc/stdlib/rand.c
@@ -0,0 +1,105 @@
+/*-
+ * 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>.
+ */
+
+#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 */
+
OpenPOWER on IntegriCloud