[U-Boot] [PATCH v6 1/3] lib: add rand() function
Michael Walle
michael at walle.cc
Sat May 26 01:43:13 CEST 2012
It's a PRNG using the simple and fast xorshift method.
Signed-off-by: Michael Walle <michael at walle.cc>
Cc: Wolfgang Denk <wd at denx.de>
---
include/common.h | 6 ++++++
lib/Makefile | 1 +
lib/rand.c | 43 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 50 insertions(+), 0 deletions(-)
create mode 100644 lib/rand.c
diff --git a/include/common.h b/include/common.h
index 4b5841e..a9cb62c 100644
--- a/include/common.h
+++ b/include/common.h
@@ -733,6 +733,12 @@ char * strmhz(char *buf, unsigned long hz);
/* lib/crc32.c */
#include <u-boot/crc.h>
+/* lib/rand.c */
+#ifdef CONFIG_RANDOM_MACADDR
+void srand(unsigned int seed);
+unsigned int rand(void);
+#endif
+
/* common/console.c */
int console_init_f(void); /* Before relocation; uses the serial stuff */
int console_init_r(void); /* After relocation; uses the console stuff */
diff --git a/lib/Makefile b/lib/Makefile
index a0fec60..74579f9 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -65,6 +65,7 @@ COBJS-y += string.o
COBJS-y += time.o
COBJS-$(CONFIG_BOOTP_PXE) += uuid.o
COBJS-y += vsprintf.o
+COBJS-$(CONFIG_RANDOM_MACADDR) += rand.o
COBJS := $(COBJS-y)
SRCS := $(COBJS:.o=.c)
diff --git a/lib/rand.c b/lib/rand.c
new file mode 100644
index 0000000..6cb76ac
--- /dev/null
+++ b/lib/rand.c
@@ -0,0 +1,43 @@
+/*
+ * Simple xorshift PRNG
+ * see http://www.jstatsoft.org/v08/i14/paper
+ *
+ * Copyright (c) 2012 Michael Walle
+ * Michael Walle <michael at walle.cc>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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 <common.h>
+
+static unsigned int y = 1U;
+
+void srand(unsigned int seed)
+{
+ y = seed;
+}
+
+unsigned int rand(void)
+{
+ y ^= (y << 13);
+ y ^= (y >> 17);
+ y ^= (y << 5);
+
+ return y;
+}
--
1.7.2.5
More information about the U-Boot
mailing list