1 files changed, 79 insertions, 0 deletions
diff --git a/innobase/ut/ut0rnd.c b/innobase/ut/ut0rnd.c
new file mode 100644
index 00000000000..3335861384f
--- /dev/null
+++ b/innobase/ut/ut0rnd.c
@@ -0,0 +1,79 @@
+/*******************************************************************
+Random numbers and hashing
+
+(c) 1994, 1995 Innobase Oy
+
+Created 5/11/1994 Heikki Tuuri
+********************************************************************/
+
+#include "ut0rnd.h"
+
+#ifdef UNIV_NONINL
+#include "ut0rnd.ic"
+#endif
+
+/* These random numbers are used in ut_find_prime */
+#define	UT_RANDOM_1	1.0412321
+#define	UT_RANDOM_2	1.1131347
+#define UT_RANDOM_3	1.0132677
+
+
+ulint	ut_rnd_ulint_counter = 65654363;
+
+/***************************************************************
+Looks for a prime number slightly greater than the given argument.
+The prime is chosen so that it is not near any power of 2. */
+
+ulint
+ut_find_prime(
+/*==========*/
+			/* out: prime */
+	ulint	n)	/* in: positive number > 100 */
+{
+	ulint	pow2;
+	ulint	i;
+	
+	n += 100;
+	
+	pow2 = 1;
+	while (pow2 * 2 < n) {
+		pow2 = 2 * pow2;
+	}
+
+	if ((double)n < 1.05 * (double)pow2) {
+		n = (ulint) ((double)n * UT_RANDOM_1);
+	}
+	
+	pow2 = 2 * pow2;
+	
+	if ((double)n > 0.95 * (double)pow2) {
+		n = (ulint) ((double)n * UT_RANDOM_2);
+	}
+	
+	if (n > pow2 - 20) {
+		n += 30;
+	}
+
+	/* Now we have n far enough from powers of 2. To make
+	n more random (especially, if it was not near 
+	a power of 2), we then multiply it by a random number. */ 
+
+	n = (ulint) ((double)n * UT_RANDOM_3);
+	
+	for (;; n++) {
+		i = 2;
+		while (i * i <= n) {
+			if (n % i == 0) {
+				goto next_n;
+			}
+			i++;
+		}
+		
+		/* Found a prime */
+		break;
+	next_n: ;
+	}
+	
+	return(n);
+}
+