X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=include%2Flinux%2Flog2.h;h=c8cf5e8ef1717d40cde2768fd0608f29924b1545;hb=47fe064831a2a949f6c1e0086f61a105e99ea867;hp=57e641e19a8106122783073291cf53adfc36acd0;hpb=874ff01bd9183ad16495acfd54e93a619d12b8b5;p=linux-2.6-omap-h63xx.git

diff --git a/include/linux/log2.h b/include/linux/log2.h
index 57e641e19a8..c8cf5e8ef17 100644
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -63,6 +63,15 @@ unsigned long __roundup_pow_of_two(unsigned long n)
 	return 1UL << fls_long(n - 1);
 }
 
+/*
+ * round down to nearest power of two
+ */
+static inline __attribute__((const))
+unsigned long __rounddown_pow_of_two(unsigned long n)
+{
+	return 1UL << (fls_long(n) - 1);
+}
+
 /**
  * ilog2 - log of base 2 of 32-bit or a 64-bit unsigned value
  * @n - parameter
@@ -159,10 +168,26 @@ unsigned long __roundup_pow_of_two(unsigned long n)
 #define roundup_pow_of_two(n)			\
 (						\
 	__builtin_constant_p(n) ? (		\
-		(n == 1) ? 0 :			\
+		(n == 1) ? 1 :			\
 		(1UL << (ilog2((n) - 1) + 1))	\
 				   ) :		\
 	__roundup_pow_of_two(n)			\
  )
 
+/**
+ * rounddown_pow_of_two - round the given value down to nearest power of two
+ * @n - parameter
+ *
+ * round the given value down to the nearest power of two
+ * - the result is undefined when n == 0
+ * - this can be used to initialise global variables from constant data
+ */
+#define rounddown_pow_of_two(n)			\
+(						\
+	__builtin_constant_p(n) ? (		\
+		(n == 1) ? 0 :			\
+		(1UL << ilog2(n))) :		\
+	__rounddown_pow_of_two(n)		\
+ )
+
 #endif /* _LINUX_LOG2_H */