The patch titled
Subject: bitops.h: add sign_extend64()
has been added to the -mm tree. Its filename is
bitopsh-add-sign_extend64.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/bitopsh-add-sign_extend64.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/bitopsh-add-sign_extend64.patch
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------------------------------------------------------
From: Martin Kepplinger <martink@xxxxxxxxx>
Subject: bitops.h: add sign_extend64()
Months back, this was discussed, see https://lkml.org/lkml/2015/1/18/289
The result was the 64-bit version being "likely fine", "valuable" and
"correct". The discussion fell asleep but since there are possible users,
let's add it.
Signed-off-by: Martin Kepplinger <martin.kepplinger@xxxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: George Spelvin <linux@xxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Maxime Coquelin <maxime.coquelin@xxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Yury Norov <yury.norov@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/bitops.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff -puN include/linux/bitops.h~bitopsh-add-sign_extend64 include/linux/bitops.h
--- a/include/linux/bitops.h~bitopsh-add-sign_extend64
+++ a/include/linux/bitops.h
@@ -173,6 +173,17 @@ static inline __s32 sign_extend32(__u32
return (__s32)(value << shift) >> shift;
}
+/**
+ * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
+ * @value: value to sign extend
+ * @index: 0 based bit index (0<=index<64) to sign bit
+ */
+static inline __s64 sign_extend64(__u64 value, int index)
+{
+ __u8 shift = 63 - index;
+ return (__s64)(value << shift) >> shift;
+}
+
static inline unsigned fls_long(unsigned long l)
{
if (sizeof(l) == 4)
_
Patches currently in -mm which might be from martink@xxxxxxxxx are
bitopsh-improve-sign_extend32s-documentation.patch
bitopsh-add-sign_extend64.patch
arch-sh-use-sign_extend64-for-sign-extension.patch
arch-sh-use-sign_extend64-for-sign-extension-2.patch
arch-x86-use-sign_extend64-for-sign-extension.patch
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