The patch titled
Introduce a generic __fls implementation
has been added to the -mm tree. Its filename is
introduce-a-generic-__fls-implementation.patch
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------------------------------------------------------
Subject: Introduce a generic __fls implementation
From: Alexander van Heukelum <heukelum@xxxxxxxxxxxxx>
This series of patches:
[1/3] adds __fls.h to asm-generic
[2/3] modifies asm-*/bitops.h for 64-bit archs to implement __fls
[3/3] modifies asm-generic/fls64.h to make use of __fls
I have compiled i386 and x86_64, and they generate the same code as before the
change. These patches make one tiny bit of the x86-unification a tiny bit
cleaner.
This patch:
Add a generic __fls implementation in the same spirit as the generic __ffs
one. It finds the last (most significant) set bit in the given long value.
Signed-off-by: Alexander van Heukelum <heukelum@xxxxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
Cc: "Luck, Tony" <tony.luck@xxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Kyle McMartin <kyle@xxxxxxxxxxx>
Cc: Grant Grundler <grundler@xxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <matthew@xxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-generic/bitops/__fls.h | 43 +++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff -puN /dev/null include/asm-generic/bitops/__fls.h
--- /dev/null
+++ a/include/asm-generic/bitops/__fls.h
@@ -0,0 +1,43 @@
+#ifndef _ASM_GENERIC_BITOPS___FLS_H_
+#define _ASM_GENERIC_BITOPS___FLS_H_
+
+#include <asm/types.h>
+
+/**
+ * __fls - find last (most-significant) set bit in a long word
+ * @word: the word to search
+ *
+ * Undefined if no set bit exists, so code should check against 0 first.
+ */
+static inline unsigned long __fls(unsigned long word)
+{
+ int num = BITS_PER_LONG - 1;
+
+#if BITS_PER_LONG == 64
+ if (!(word & (~0ul << 32))) {
+ num -= 32;
+ word <<= 32;
+ }
+#endif
+ if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
+ num -= 16;
+ word <<= 16;
+ }
+ if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
+ num -= 8;
+ word <<= 8;
+ }
+ if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
+ num -= 4;
+ word <<= 4;
+ }
+ if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
+ num -= 2;
+ word <<= 2;
+ }
+ if (!(word & (~0ul << (BITS_PER_LONG-1))))
+ num -= 1;
+ return num;
+}
+
+#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */
_
Patches currently in -mm which might be from heukelum@xxxxxxxxxxxxx are
git-x86.patch
introduce-a-generic-__fls-implementation.patch
implement-__fls-on-all-64-bit-archs.patch
use-__fls-for-fls64-on-64-bit-archs.patch
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