From 11ec50caedb56e3a87715edeff6a1852e6ae5416 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 12 Dec 2013 17:40:22 +0000 Subject: [PATCH] word-at-a-time: provide generic big-endian zero_bytemask implementation Whilst architectures may be able to do better than this (which they can, by simply defining their own macro), this is a generic stab at a zero_bytemask implementation for the asm-generic, big-endian word-at-a-time implementation. On arm64, a clz instruction is used to implement the fls efficiently. Signed-off-by: Will Deacon Signed-off-by: Linus Torvalds --- include/asm-generic/word-at-a-time.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/asm-generic/word-at-a-time.h b/include/asm-generic/word-at-a-time.h index 3f21f1b72e4..d3909effd72 100644 --- a/include/asm-generic/word-at-a-time.h +++ b/include/asm-generic/word-at-a-time.h @@ -49,4 +49,12 @@ static inline bool has_zero(unsigned long val, unsigned long *data, const struct return (val + c->high_bits) & ~rhs; } +#ifndef zero_bytemask +#ifdef CONFIG_64BIT +#define zero_bytemask(mask) (~0ul << fls64(mask)) +#else +#define zero_bytemask(mask) (~0ul << fls(mask)) +#endif /* CONFIG_64BIT */ +#endif /* zero_bytemask */ + #endif /* _ASM_WORD_AT_A_TIME_H */ -- 2.43.2