1 files changed, 54 insertions, 0 deletions

diff --git a/firmware/common/ffs.c b/firmware/common/ffs.c
new file mode 100644
index 0000000000..e3dc9b0dc5
--- /dev/null
+++ b/firmware/common/ffs.c
@@ -0,0 +1,54 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2008 by Michael Sevakis
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+#include <inttypes.h>
+
+/* find_first_set_bit() - this is a C version of the ffs algorithm devised
+ * by D.Seal and posted to comp.sys.arm on  16 Feb 1994.
+ *
+ * Find the index of the least significant set bit in the word.
+ * return values:
+ *   0  - bit 0 is set
+ *   1  - bit 1 is set
+ *   ...
+ *   31 - bit 31 is set
+ *   32 - no bits set
+ */
+
+/* Table shared with assembly code */
+const uint8_t L_ffs_table[64] ICONST_ATTR =
+{
+/*   0   1   2   3   4   5   6   7           */
+/* ----------------------------------------- */
+    32,  0,  1, 12,  2,  6,  0, 13, /*  0- 7 */
+     3,  0,  7,  0,  0,  0,  0, 14, /*  8-15 */
+    10,  4,  0,  0,  8,  0,  0, 25, /* 16-23 */
+     0,  0,  0,  0,  0, 21, 27, 15, /* 24-31 */
+    31, 11,  5,  0,  0,  0,  0,  0, /* 32-39 */
+     9,  0,  0, 24,  0,  0, 20, 26, /* 40-47 */
+    30,  0,  0,  0,  0, 23,  0, 19, /* 48-55 */
+    29,  0, 22, 18, 28, 17, 16,  0, /* 56-63 */
+};
+
+#if !defined(CPU_COLDFIRE)
+int find_first_set_bit(uint32_t val)
+{
+    return L_ffs_table[((val & -val)*0x0450fbaf) >> 26];
+}
+#endif