Add hweight64()

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/lib/hweight.c b/lib/hweight.c
index 738ed277380118eca1672e7095023c95ac7340c6..bc9b51bc22704cb6b285aa227779c43397e5e661 100644 (file)
--- a/lib/hweight.c
+++ b/lib/hweight.c
@@ -17,3 +17,17 @@ unsigned int hweight32(uint32_t w)
        res = res + (res >> 8);
        return (res + (res >> 16)) & 0x000000FF;
 }
+
+unsigned int hweight64(uint64_t w)
+{
+#if BITS_PER_LONG == 32
+       return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w);
+#else
+       uint64_t res = w - ((w >> 1) & 0x5555555555555555ul);
+       res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
+       res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
+       res = res + (res >> 8);
+       res = res + (res >> 16);
+       return (res + (res >> 32)) & 0x00000000000000FFul;
+#endif
+}

diff --git a/lib/hweight.h b/lib/hweight.h
index 1965eaa641186a2995063d50db48bf63581161eb..68861ddd9dc6e5cf808e09e38a6ee1248f1b51c6 100644 (file)
--- a/lib/hweight.h
+++ b/lib/hweight.h
@@ -5,5 +5,6 @@
 
 unsigned int hweight8(uint8_t w);
 unsigned int hweight32(uint32_t w);
+unsigned int hweight64(uint64_t w);
 
 #endif