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| author | Martin Kepplinger <martink@posteo.de> | 2015-11-06 16:30:58 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-06 17:50:42 -0800 |
| commit | e2eb53aa96754b97d158eff884dde88abbad925e (patch) | |
| tree | 0159c242d120da9cd02dc3d59a8b7787da811fb8 /include/linux/bitops.h | |
| parent | cd2c3e7f94f3d8210320bfb9b5712bdcbb12f8db (diff) | |
| download | op-kernel-dev-e2eb53aa96754b97d158eff884dde88abbad925e.zip op-kernel-dev-e2eb53aa96754b97d158eff884dde88abbad925e.tar.gz | |
bitops.h: improve sign_extend32()'s documentation
It is often overlooked that sign_extend32(), despite its name, is safe to
use for 16 and 8 bit types as well. This should help prevent sign
extension being done manually some other way.
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/linux/bitops.h')
| -rw-r--r-- | include/linux/bitops.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index e635533..5629923 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -164,6 +164,8 @@ static inline __u8 ror8(__u8 word, unsigned int shift) * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit * @value: value to sign extend * @index: 0 based bit index (0<=index<32) to sign bit + * + * This is safe to use for 16- and 8-bit types as well. */ static inline __s32 sign_extend32(__u32 value, int index) { |
