On Mon, Jan 05, 2015 at 01:20:57PM +0000, David Laight wrote:
> > +/* simplify initialization of mask field */
> > +#define CYCLECOUNTER_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1)
> > : -1)
>
> That has me chasing through the C integer promotion rules.
> Better might be:
> ((bits) < 64 ? (1ULL << (bits)) - 1 : (((1ULL << 63) - 1) << 1) + 1)
> I actually suspect there is a standard definition somewhere?
This is an exact copy of CLOCKSOURCE_MASK, and if wrong, then both are
wrong. In any case, I can't see any issue here. Is not
(some_int_type) -1
always equal to
0xf...(width of type)
for all integer types, when using 2s compliment?
Thanks
Richard
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