diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/carta_random32.c | 41 |
2 files changed, 42 insertions, 1 deletions
diff --git a/lib/Makefile b/lib/Makefile index 8e6662bb9c37..59070dbfbeb4 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -5,7 +5,7 @@ lib-y := 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 irq_regs.o + sha1.o irq_regs.o carta_random32.o lib-$(CONFIG_MMU) += ioremap.o lib-$(CONFIG_SMP) += cpumask.o diff --git a/lib/carta_random32.c b/lib/carta_random32.c new file mode 100644 index 000000000000..ca82df70eee4 --- /dev/null +++ b/lib/carta_random32.c @@ -0,0 +1,41 @@ +/* + * Copyright (c) 2002-2006 Hewlett-Packard Development Company, L.P. + * Contributed by David Mosberger-Tang <davidm@hpl.hp.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + * 02111-1307 USA + */ +#include <linux/types.h> +#include <linux/module.h> + +/* + * 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). + */ +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_GPL(carta_random32); |