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-rw-r--r--include/linux/bitops.h45
1 files changed, 45 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 387a818..e14e6c7 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -38,6 +38,43 @@ static inline int generic_ffs(int x)
return r;
}
+/**
+ * fls - find last (most-significant) bit set
+ * @x: the word to search
+ *
+ * This is defined the same way as ffs.
+ * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
+ */
+static inline int generic_fls(int x)
+{
+ int r = 32;
+
+ if (!x)
+ return 0;
+ if (!(x & 0xffff0000u)) {
+ x <<= 16;
+ r -= 16;
+ }
+ if (!(x & 0xff000000u)) {
+ x <<= 8;
+ r -= 8;
+ }
+ if (!(x & 0xf0000000u)) {
+ x <<= 4;
+ r -= 4;
+ }
+ if (!(x & 0xc0000000u)) {
+ x <<= 2;
+ r -= 2;
+ }
+ if (!(x & 0x80000000u)) {
+ x <<= 1;
+ r -= 1;
+ }
+ return r;
+}
+
+
/*
* hweightN: returns the hamming weight (i.e. the number
* of bits set) of a N-bit word
@@ -82,6 +119,14 @@ static inline unsigned int generic_hweight8(unsigned int w)
# define __clear_bit generic_clear_bit
#endif
+#ifndef ffs
+# define ffs generic_ffs
+#endif
+
+#ifndef fls
+# define fls generic_fls
+#endif
+
/**
* __set_bit - Set a bit in memory
* @nr: the bit to set