This patch adds the carta_random32() routine to the library.
This is a very simple and very efficient random number generator
implementing Carta's algorithm. This routine is used by
perfmon2 to compute a randomized sampling period. On some
platforms, such as IA-64, this routine may be implemented in
assembly directly.
diff -urp --exclude-from=/tmp/excl31584 linux-2.6.17.9.base/lib/Makefile linux-2.6.17.9/lib/Makefile
--- linux-2.6.17.9.base/lib/Makefile 2006-08-18 09:26:24.000000000 -0700
+++ linux-2.6.17.9/lib/Makefile 2006-08-21 03:37:45.000000000 -0700
@@ -5,7 +5,7 @@
lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \
idr.o div64.o int_sqrt.o bitmap.o extable.o prio_tree.o \
- sha1.o
+ sha1.o carta_random32.o
lib-$(CONFIG_SMP) += cpumask.o
Only in linux-2.6.17.9/lib: carta_random32.c
Only in linux-2.6.17.9: perfmon
--- linux-2.6.17.9.base/lib/carta_random32.c 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.17.9/lib/carta_random32.c 2006-08-21 03:37:46.000000000 -0700
@@ -0,0 +1,29 @@
+/*
+ * Fast, simple, yet decent quality random number generator based on
+ * a paper by David G. Carta ("Two Fast Implementations of the
+ * `Minimal Standard' Random Number Generator," Communications of the
+ * ACM, January, 1990).
+ *
+ * Copyright (c) 2002-2005 Hewlett-Packard Development Company, L.P.
+ * Contributed by David Mosberger-Tang <[email protected]>
+ */
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/perfmon.h>
+
+#ifndef __HAVE_ARCH_CARTA_RANDOM32
+u64 carta_random32 (u64 seed)
+{
+# define A 16807
+# define M ((u32) 1 << 31)
+ u64 s, prod = A * seed, p, q;
+
+ p = (prod >> 31) & (M - 1);
+ q = (prod >> 0) & (M - 1);
+ s = p + q;
+ if (s >= M)
+ s -= M - 1;
+ return s;
+}
+EXPORT_SYMBOL(carta_random32);
+#endif
-
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