Messages in this thread Patch in this message | | | From | Martin Kepplinger <> | Subject | [PATCH 2/5] bitops.h: add sign_extend64() | Date | Fri, 16 Oct 2015 11:07:04 +0200 |
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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 only fell asleep but since there are possible users, let's add it.
Signed-off-by: Martin Kepplinger <martin.kepplinger@theobroma-systems.com> --- include/linux/bitops.h | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 5629923..2b8ed12 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) -- 2.1.4
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