summaryrefslogtreecommitdiffstats
path: root/include/linux/log2.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/linux/log2.h')
-rw-r--r--include/linux/log2.h26
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/log2.h b/include/linux/log2.h
index 3979c60325ff..d02e1a547a7e 100644
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -43,6 +43,15 @@ int __ilog2_u64(u64 n)
}
#endif
+/*
+ * round up to nearest power of two
+ */
+static inline __attribute__((const))
+unsigned long __roundup_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
@@ -128,4 +137,21 @@ int __ilog2_u64(u64 n)
__ilog2_u64(n) \
)
+/**
+ * roundup_pow_of_two - round the given value up to nearest power of two
+ * @n - parameter
+ *
+ * round the given balue up 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 roundup_pow_of_two(n) \
+( \
+ __builtin_constant_p(n) ? ( \
+ (n == 1) ? 0 : \
+ (1UL << (ilog2((n) - 1) + 1)) \
+ ) : \
+ __roundup_pow_of_two(n) \
+ )
+
#endif /* _LINUX_LOG2_H */