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-rw-r--r--include/linux/bitops.h29
1 files changed, 27 insertions, 2 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index c05a29c..25b8b2f 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
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