The patch titled
Add a "rounddown_pow_of_two" routine to log2.h
has been added to the -mm tree. Its filename is
add-a-rounddown_pow_of_two-routine-to-log2h.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Add a "rounddown_pow_of_two" routine to log2.h
From: "Robert P. J. Day" <rpjday@xxxxxxxxxxxxxx>
To go along with the existing "roundup_pow_of_two" routine, add one for
rounding down since that operation appears to crop up on a regular basis in
the source tree.
Signed-off-by: Robert P. J. Day <rpjday@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/log2.h | 25 +++++++++++++++++++++++++
1 files changed, 25 insertions(+)
diff -puN include/linux/log2.h~add-a-rounddown_pow_of_two-routine-to-log2h include/linux/log2.h
--- a/include/linux/log2.h~add-a-rounddown_pow_of_two-routine-to-log2h
+++ a/include/linux/log2.h
@@ -63,6 +63,15 @@ unsigned long __roundup_pow_of_two(unsig
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
@@ -165,4 +174,20 @@ unsigned long __roundup_pow_of_two(unsig
__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 */
_
Patches currently in -mm which might be from rpjday@xxxxxxxxxxxxxx are
git-kvm.patch
git-mtd.patch
pcmcia-delete-obsolete-pcmcia_ioctl-feature.patch
remove-dead-references-to-module_parm-macro.patch
m68knommu-remove-unused-config-symbol-config_disktel.patch
force-erroneous-inclusions-of-compiler-h-files-to-be-errors.patch
force-erroneous-inclusions-of-compiler-h-files-to-be-errors-fix.patch
kconfig-make-instrumentation-support-non-experimental.patch
remove-superfluous-definition-of-__setup_null_param-macro-and-broken-for-module-__setup_param.patch
remove-valueless-definition-of-hard-selected-ramfs-option.patch
remove-final-traces-of-long-deprecated-ramdisk-kernel.patch
add-a-rounddown_pow_of_two-routine-to-log2h.patch
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