path: root/include
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authorMartin Kepplinger <martink@posteo.de>2015-11-06 16:31:02 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-06 17:50:42 -0800
commit48e203e21b29cd4b2c58403fe8bca68e2e854895 (patch)
tree7318382eb04eeea8d3370ca03a688b99592916da /include
parente2eb53aa96754b97d158eff884dde88abbad925e (diff)
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@theobroma-systems.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: George Spelvin <linux@horizon.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Maxime Coquelin <maxime.coquelin@st.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Yury Norov <yury.norov@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 5629923a8701..2b8ed123ad36 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -173,6 +173,17 @@ static inline __s32 sign_extend32(__u32 value, int index)
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)