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| author | Ahmad Fatoum <a.fatoum@pengutronix.de> | 2023-11-22 18:29:39 +0100 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2023-11-23 15:50:35 +0100 |
| commit | dde1c3e59b88a74a2eb85e9874384936ae20cb57 (patch) | |
| tree | 06fc76c2535ddae56085ef42b8888d7adb14eef7 /include/linux | |
| parent | 2376924e24c003def53712d91524f8ffaa6903e7 (diff) | |
| download | barebox-dde1c3e59b88a74a2eb85e9874384936ae20cb57.tar.gz barebox-dde1c3e59b88a74a2eb85e9874384936ae20cb57.tar.xz | |
include: import Linux word-at-a-time.h
The Linux <linux/word-at-a-time.h> interface is used to optimize
searching for bytes in strings by doing word-size comparisons. This will
be used in the implementation of strscpy in a follow-up commit, so
import the generic version here.
A good overview on the interface is available at LWN[1]. Note that
it discuss Linux v3.5. The asm-generic version imported here works
also on little-endian and not only big-endian[2].
[1]: https://lwn.net/Articles/501492/
[2]: Linux kernel commit a6e2f029ae34 ("Make asm/word-at-a-time.h
available on all architectures").
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20231122172951.376531-9-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/kernel.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index da6121888e..4e50f60751 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -11,6 +11,14 @@ #include <linux/instruction_pointer.h> #include <linux/minmax.h> +/** + * REPEAT_BYTE - repeat the value @x multiple times as an unsigned long value + * @x: value to repeat + * + * NOTE: @x is not checked for > 0xff; larger values produce odd results. + */ +#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) + #define ALIGN(x, a) __ALIGN_MASK(x, (typeof(x))(a) - 1) #define ALIGN_DOWN(x, a) ALIGN((x) - ((a) - 1), (a)) #define __ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask)) |