This adds a helper function that extends any signed value smaller than 8 bits to a s8.
Signed-off-by: Martin Kepplinger <[email protected]> --- include/linux/bitops.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 5d858e0..3c2a539 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -161,6 +161,17 @@ static inline __u8 ror8(__u8 word, unsigned int shift) } /** + * sign_extend8 - sign extend a 8-bit value using specified bit as sign-bit + * @value: value to sign extend + * @index: 0 based bit index (0<=index<8) to sign bit + */ +static inline __s8 sign_extend8(__u8 value, int index) +{ + __u8 shift = 7 - index; + return (__s8)(value << shift) >> 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 -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
