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    Subject[tip:perf/core] bitops: Provide compile time HWEIGHT{8,16,32,64}
    Commit-ID:  9f41699ed067fa695faff8e2e9981b2550abec62
    Gitweb: http://git.kernel.org/tip/9f41699ed067fa695faff8e2e9981b2550abec62
    Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
    AuthorDate: Fri, 22 Jan 2010 15:59:29 +0100
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Fri, 29 Jan 2010 09:01:39 +0100

    bitops: Provide compile time HWEIGHT{8,16,32,64}

    Provide compile time versions of hweight.

    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    LKML-Reference: <20100122155535.797688466@chello.nl>
    [ Remove some whitespace damage while we are at it ]
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    include/linux/bitops.h | 18 ++++++++++++++++--
    1 files changed, 16 insertions(+), 2 deletions(-)

    diff --git a/include/linux/bitops.h b/include/linux/bitops.h
    index c05a29c..ba0fd1e 100644
    --- a/include/linux/bitops.h
    +++ b/include/linux/bitops.h
    @@ -25,7 +25,7 @@
    static __inline__ int get_bitmask_order(unsigned int count)
    {
    int order;
    -
    +
    order = fls(count);
    return order; /* We could be slightly more clever with -1 here... */
    }
    @@ -33,7 +33,7 @@ static __inline__ int get_bitmask_order(unsigned int count)
    static __inline__ int get_count_order(unsigned int count)
    {
    int order;
    -
    +
    order = fls(count) - 1;
    if (count & (count - 1))
    order++;
    @@ -45,6 +45,20 @@ static inline unsigned long hweight_long(unsigned long w)
    return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
    }

    +#define HWEIGHT8(w) \
    + ( (!!((w) & (1ULL << 0))) + \
    + (!!((w) & (1ULL << 1))) + \
    + (!!((w) & (1ULL << 2))) + \
    + (!!((w) & (1ULL << 3))) + \
    + (!!((w) & (1ULL << 4))) + \
    + (!!((w) & (1ULL << 5))) + \
    + (!!((w) & (1ULL << 6))) + \
    + (!!((w) & (1ULL << 7))) )
    +
    +#define HWEIGHT16(w) (HWEIGHT8(w) + HWEIGHT8(w >> 8))
    +#define HWEIGHT32(w) (HWEIGHT16(w) + HWEIGHT16(w >> 16))
    +#define HWEIGHT64(w) (HWEIGHT32(w) + HWEIGHT32(w >> 32))
    +
    /**
    * rol32 - rotate a 32-bit value left
    * @word: value to rotate

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      Last update: 2010-01-29 10:33    [W:0.032 / U:30.452 seconds]
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