Re: [PATCH 1/1] unify DMA_..BIT_MASK definitions: v3.1

Andreas Schwab
2007-10-05T21:24:39Z

"Robert P. J. Day" <rpjday@mindspring.com> writes:

> On Fri, 5 Oct 2007, Andrew Morton wrote:
>
>> -#define DMA_BIT_MASK(n) ((1ULL<<(n))-1)
>> +#define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
>
> or you could take advantage of the macros in kernel.h and write that
> as:
>
> +#define DMA_BIT_MASK(n) (((n) == 64) ? ULLONG_MAX : ((1ULL<<(n))-1))

#define DMA_BIT_MASK(n) ((u64)-1 >> (64 - (n)))

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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