1 files changed, 27 insertions, 2 deletions

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index c05a29cb9bb2..25b8b2f33ae9 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -25,7 +25,7 @@
 static __inline__ int get_bitmask_order(unsigned int count)
 {
         int order;
-        
+
         order = fls(count);
         return order;   /* We could be slightly more clever with -1 here... */
 }
@@ -33,7 +33,7 @@ static __inline__ int get_bitmask_order(unsigned int count)
 static __inline__ int get_count_order(unsigned int count)
 {
         int order;
-        
+
         order = fls(count) - 1;
         if (count & (count - 1))
                 order++;
@@ -45,6 +45,31 @@ static inline unsigned long hweight_long(unsigned long w)
         return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
 }
 
+/*
+ * Clearly slow versions of the hweightN() functions, their benefit is
+ * of course compile time evaluation of constant arguments.
+ */
+#define HWEIGHT8(w)                                     \
+      ( BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) +   \
+        (!!((w) & (1ULL << 0))) +                       \
+        (!!((w) & (1ULL << 1))) +                       \
+        (!!((w) & (1ULL << 2))) +                       \
+        (!!((w) & (1ULL << 3))) +                       \
+        (!!((w) & (1ULL << 4))) +                       \
+        (!!((w) & (1ULL << 5))) +                       \
+        (!!((w) & (1ULL << 6))) +                       \
+        (!!((w) & (1ULL << 7))) )
+
+#define HWEIGHT16(w) (HWEIGHT8(w)  + HWEIGHT8((w) >> 8))
+#define HWEIGHT32(w) (HWEIGHT16(w) + HWEIGHT16((w) >> 16))
+#define HWEIGHT64(w) (HWEIGHT32(w) + HWEIGHT32((w) >> 32))
+
+/*
+ * Type invariant version that simply casts things to the
+ * largest type.
+ */
+#define HWEIGHT(w)   HWEIGHT64((u64)(w))
+
 /**
  * rol32 - rotate a 32-bit value left
  * @word: value to rotate