diff options
| author | Martin Kepplinger <[email protected]> | 2015-11-06 16:31:02 -0800 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2015-11-06 17:50:42 -0800 |
| commit | 48e203e21b29cd4b2c58403fe8bca68e2e854895 (patch) | |
| tree | 7318382eb04eeea8d3370ca03a688b99592916da | |
| parent | e2eb53aa96754b97d158eff884dde88abbad925e (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 <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: George Spelvin <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Maxime Coquelin <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Yury Norov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | include/linux/bitops.h | 11 |
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) |