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Re: [Qemu-devel] [PATCH 1/5] BIT_RANGE convenience macro
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH 1/5] BIT_RANGE convenience macro |
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Date: |
Thu, 16 Jun 2016 19:23:09 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 |
On 16/06/2016 19:12, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> e.g. BIT_RANGE(15, 0) gives 0xff00
That looks more like BIT_RANGE(15, 8). :)
Paolo
> Suggested by: Paolo Bonzini <address@hidden>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---
> include/qemu/bitops.h | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
> index 755fdd1..e411688 100644
> --- a/include/qemu/bitops.h
> +++ b/include/qemu/bitops.h
> @@ -23,6 +23,9 @@
> #define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
> #define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
> #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE *
> sizeof(long))
> +/* e.g. BIT_RANGE(15, 0) -> 0xff00 */
> +#define BIT_RANGE(hb, lb) ((2ull << (hb)) - (1ull << (lb)))
> +
>