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Re: [Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro |
Date: |
Mon, 11 Nov 2013 12:57:29 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 |
Am 11.11.2013 08:44, schrieb Alexey Kardashevskiy:
> This adds a macro to calculate the highest bit set.
Isn't that already available as ffs / clz GCC builtin with wrapper in
qemu/bitops.h? What's the difference to your macro? CC'ing Paolo.
Andreas
> If used on constant
> values, no code will be generated.
>
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
> include/qemu/bitops.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
> index 304c90c..98ba42a 100644
> --- a/include/qemu/bitops.h
> +++ b/include/qemu/bitops.h
> @@ -23,6 +23,18 @@
> #define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
> #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
>
> +#define __BITNR(m, n) ((m) == ((m) & (1<<(n)))) ? (n) :
> +#define BITNR(m) \
> + __BITNR((m), 31) __BITNR((m), 30) __BITNR((m), 29) __BITNR((m), 28) \
> + __BITNR((m), 27) __BITNR((m), 26) __BITNR((m), 25) __BITNR((m), 24) \
> + __BITNR((m), 23) __BITNR((m), 22) __BITNR((m), 21) __BITNR((m), 20) \
> + __BITNR((m), 19) __BITNR((m), 18) __BITNR((m), 17) __BITNR((m), 16) \
> + __BITNR((m), 15) __BITNR((m), 14) __BITNR((m), 13) __BITNR((m), 12) \
> + __BITNR((m), 11) __BITNR((m), 10) __BITNR((m), 9) __BITNR((m), 8) \
> + __BITNR((m), 7) __BITNR((m), 6) __BITNR((m), 5) __BITNR((m), 4) \
> + __BITNR((m), 3) __BITNR((m), 2) __BITNR((m), 1) __BITNR((m), 0) \
> + -1
> +
> /**
> * set_bit - Set a bit in memory
> * @nr: the bit to set
>
--
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- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, (continued)
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Igor Mammedov, 2013/11/12
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Alexey Kardashevskiy, 2013/11/12
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Andreas Färber, 2013/11/12
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Alexey Kardashevskiy, 2013/11/12
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Paolo Bonzini, 2013/11/13
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Igor Mammedov, 2013/11/12
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Alexey Kardashevskiy, 2013/11/12
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Igor Mammedov, 2013/11/13
- Re: [Qemu-devel] [PATCH v3 4/6] qemu-option: support +foo/-foo command line agruments, Paolo Bonzini, 2013/11/13
[Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro, Alexey Kardashevskiy, 2013/11/11
- Re: [Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro,
Andreas Färber <=
- Re: [Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro, Alexey Kardashevskiy, 2013/11/11
- Re: [Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro, Alexey Kardashevskiy, 2013/11/12
- Re: [Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro, Paolo Bonzini, 2013/11/13
- Re: [Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro, Alexey Kardashevskiy, 2013/11/14
- Re: [Qemu-devel] [PATCH v3 5/6] bitops: add BITNR macro, Paolo Bonzini, 2013/11/14
[Qemu-devel] [PATCH v3 3/6] target-ppc: add "compat" CPU option, Alexey Kardashevskiy, 2013/11/11
[Qemu-devel] [PATCH v3 2/6] target-ppc: make use of new -cpu suboptions handling, Alexey Kardashevskiy, 2013/11/11
[Qemu-devel] [PATCH v3 6/6] target-ppc: demonstrate new "vsx" property, Alexey Kardashevskiy, 2013/11/11