bitops: Provide compile time HWEIGHT{8,16,32,64}
Peter Zijlstra [Fri, 22 Jan 2010 14:59:29 +0000 (15:59 +0100)]
Provide compile time versions of hweight.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <20100122155535.797688466@chello.nl>
[ Remove some whitespace damage while we are at it ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/bitops.h

index c05a29c..ba0fd1e 100644 (file)
@@ -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 +45,20 @@ static inline unsigned long hweight_long(unsigned long w)
        return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
 }
 
+#define HWEIGHT8(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))
+
 /**
  * rol32 - rotate a 32-bit value left
  * @word: value to rotate