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authorJeff Garzik <jeff@garzik.org>2006-03-29 17:18:49 -0500
committerJeff Garzik <jeff@garzik.org>2006-03-29 17:18:49 -0500
commite02a4cabfcb9a999b74a2e2e6f13ffcb7ff2d606 (patch)
tree2f3db60be4c57eca2a4c3ab3f3122dcf1ec0c624 /include/asm-generic/bitops/ffs.h
parent600511e86babe3727264a0883a3a264f6fb6caf5 (diff)
parentf3cab8a0b1a772dc8b055b7affa567a366627c9e (diff)
Merge branch 'master'
Diffstat (limited to 'include/asm-generic/bitops/ffs.h')
-rw-r--r--include/asm-generic/bitops/ffs.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/ffs.h b/include/asm-generic/bitops/ffs.h
new file mode 100644
index 00000000000..fbbb43af7dc
--- /dev/null
+++ b/include/asm-generic/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_ */