lkml.org 
[lkml]   [2017]   [Jun]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v12 5/6] lib: add bitrev8x4()
    Date
    Add a function to reverse bytes within a 32 bit word.
    Operate on a u32 rather than individual bytes.

    Signed-off-by: Joshua Clayton <stillcompiling@gmail.com>
    ---
    include/linux/bitrev.h | 19 +++++++++++++++++++
    1 file changed, 19 insertions(+)

    diff --git a/include/linux/bitrev.h b/include/linux/bitrev.h
    index fb790b8449c1..b97be27e5a85 100644
    --- a/include/linux/bitrev.h
    +++ b/include/linux/bitrev.h
    @@ -29,6 +29,8 @@ static inline u32 __bitrev32(u32 x)

    #endif /* CONFIG_HAVE_ARCH_BITREVERSE */

    +#define __bitrev8x4(x) (__bitrev32(swab32(x)))
    +
    #define __constant_bitrev32(x) \
    ({ \
    u32 __x = x; \
    @@ -50,6 +52,15 @@ static inline u32 __bitrev32(u32 x)
    __x; \
    })

    +#define __constant_bitrev8x4(x) \
    +({ \
    + u32 __x = x; \
    + __x = ((__x & (u32)0xF0F0F0F0UL) >> 4) | ((__x & (u32)0x0F0F0F0FUL) << 4); \
    + __x = ((__x & (u32)0xCCCCCCCCUL) >> 2) | ((__x & (u32)0x33333333UL) << 2); \
    + __x = ((__x & (u32)0xAAAAAAAAUL) >> 1) | ((__x & (u32)0x55555555UL) << 1); \
    + __x; \
    +})
    +
    #define __constant_bitrev8(x) \
    ({ \
    u8 __x = x; \
    @@ -75,6 +86,14 @@ static inline u32 __bitrev32(u32 x)
    __bitrev16(__x); \
    })

    +#define bitrev8x4(x) \
    +({ \
    + u32 __x = x; \
    + __builtin_constant_p(__x) ? \
    + __constant_bitrev8x4(__x) : \
    + __bitrev8x4(__x); \
    + })
    +
    #define bitrev8(x) \
    ({ \
    u8 __x = x; \
    --
    2.11.0
    \
     
     \ /
      Last update: 2017-06-05 00:16    [W:3.232 / U:0.132 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site