summaryrefslogtreecommitdiff
path: root/tools/testing/radix-tree/linux/bitops/ffs.h
diff options
context:
space:
mode:
authorRich Felker <dalias@libc.org>2016-03-30 00:53:03 +0300
committerRich Felker <dalias@libc.org>2016-03-30 00:53:03 +0300
commit16b02d711f4059b8338ef967064195b47cae65ea (patch)
tree6d3e0b7629210b56f8d6cfa39184c878d8a15367 /tools/testing/radix-tree/linux/bitops/ffs.h
parentb15d53d009558d14c4f394a6d1fa2039c7f45c43 (diff)
parentf55532a0c0b8bb6148f4e07853b876ef73bc69ca (diff)
downloadlinux-16b02d711f4059b8338ef967064195b47cae65ea.tar.xz
Merge tag 'v4.6-rc1'
Linux 4.6-rc1
Diffstat (limited to 'tools/testing/radix-tree/linux/bitops/ffs.h')
-rw-r--r--tools/testing/radix-tree/linux/bitops/ffs.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/tools/testing/radix-tree/linux/bitops/ffs.h b/tools/testing/radix-tree/linux/bitops/ffs.h
new file mode 100644
index 000000000000..fbbb43af7dc0
--- /dev/null
+++ b/tools/testing/radix-tree/linux/bitops/ffs.h
@@ -0,0 +1,41 @@
+#ifndef _ASM_GENERIC_BITOPS_FFS_H_
+#define _ASM_GENERIC_BITOPS_FFS_H_
+
+/**
+ * ffs - find first bit set
+ * @x: the word to search
+ *
+ * This is defined the same way as
+ * the libc and compiler builtin ffs routines, therefore
+ * differs in spirit from the above ffz (man ffs).
+ */
+static inline int ffs(int x)
+{
+ int r = 1;
+
+ if (!x)
+ return 0;
+ if (!(x & 0xffff)) {
+ x >>= 16;
+ r += 16;
+ }
+ if (!(x & 0xff)) {
+ x >>= 8;
+ r += 8;
+ }
+ if (!(x & 0xf)) {
+ x >>= 4;
+ r += 4;
+ }
+ if (!(x & 3)) {
+ x >>= 2;
+ r += 2;
+ }
+ if (!(x & 1)) {
+ x >>= 1;
+ r += 1;
+ }
+ return r;
+}
+
+#endif /* _ASM_GENERIC_BITOPS_FFS_H_ */