+static inline unsigned int hweight8(unsigned int w)
+{
+ unsigned int res = w - ((w >> 1) & 0x55);
+ res = (res & 0x33) + ((res >> 2) & 0x33);
+ return (res + (res >> 4)) & 0x0F;
+}
+
+static inline unsigned int hweight16(unsigned int w)
+{
+ unsigned int res = w - ((w >> 1) & 0x5555);
+ res = (res & 0x3333) + ((res >> 2) & 0x3333);
+ res = (res + (res >> 4)) & 0x0F0F;
+ return (res + (res >> 8)) & 0x00FF;
+}
+
+/**
+ * DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union
+ *
+ * @TYPE: The type of each flexible array element
+ * @NAME: The name of the flexible array member
+ *
+ * In order to have a flexible array member in a union or alone in a
+ * struct, it needs to be wrapped in an anonymous struct with at least 1
+ * named member, but that member can be empty.
+ */
+#define DECLARE_FLEX_ARRAY(TYPE, NAME) \
+ struct { \
+ struct { } __empty_ ## NAME; \
+ TYPE NAME[]; \
+ }
+
+#define __bf_shf(x) (__builtin_ffsll(x) - 1)
+
+#define FIELD_MAX(_mask) \
+ ({ \
+ (typeof(_mask))((_mask) >> __bf_shf(_mask)); \
+ })
+