[PATCH 1/5] bitops.h: Improve sign_extend32()'s documentation

From: Martin Kepplinger
Date: Fri Oct 16 2015 - 05:12:26 EST


It is often overlooked that sign_extend32(), despite it's name, is safe
to use for 16 and 8 bit types aswell. This should help that sign extension
isn't done manually some other way.

Signed-off-by: Martin Kepplinger <martin.kepplinger@xxxxxxxxxxxxxxxxxxxxx>
---
include/linux/bitops.h | 2 ++
1 file changed, 2 insertions(+)

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)
{
--
2.1.4

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