From: David Howells <[email protected]>
Alter roundup_pow_of_two() so that it can make use of long_log2() on a constant
to produce a constant value, retaining the ability for an arch to override it
in the non-const case.
This permits the function to be used to initialise variables.
Signed-Off-By: David Howells <[email protected]>
---
include/linux/kernel.h | 6 ------
include/linux/log2.h | 23 +++++++++++++++++++++++
2 files changed, 23 insertions(+), 6 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index e8c6c66..e5947fb 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -155,12 +155,6 @@ #endif
unsigned long int_sqrt(unsigned long);
-static inline unsigned long
-__attribute_const__ roundup_pow_of_two(unsigned long x)
-{
- return 1UL << fls_long(x - 1);
-}
-
extern int printk_ratelimit(void);
extern int __printk_ratelimit(int ratelimit_jiffies, int ratelimit_burst);
diff --git a/include/linux/log2.h b/include/linux/log2.h
index a2f6858..2b55af0 100644
--- a/include/linux/log2.h
+++ b/include/linux/log2.h
@@ -74,6 +74,15 @@ #endif
#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);
+}
+
+/*
* constant-capable 32-bit log of base 2 calculation
* - this can be used to initialise global variables from constant data, hence
* the massive ternary operator construction
@@ -218,4 +227,18 @@ ( \
__get_order(n, PAGE_SHIFT) \
)
+/*
+ * round up to 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 << (long_log2((n) - 1) + 1)) \
+ ) : \
+ __roundup_pow_of_two(n) \
+ )
+
#endif /* _LINUX_LOG2_H */
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
