Re: [Xen-devel] [PATCH v4 02/11] x86/intel_pstate: add some calculation related support

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.07.15 at 07:48, <wei.w.wang@xxxxxxxxx> wrote:
>> > +/*
>> > + * clamp_t - return a value clamped to a given range using a given
>> > +type
>> > + * @type: the type of variable to use
>> > + * @val: current value
>> > + * @lo: minimum allowable value
>> > + * @hi: maximum allowable value
>> > + *
>> > + * This macro does no typechecking and uses temporary variables of
>> > +type
>> > + * 'type' to make all the comparisons.
>> > + */
>> > +#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo),
>> > +hi)
>> 
>> Shouldn't you also add a type checking variant then (which ought to be used
>> instead of the one above wherever possible)?
> 
> Hi Jan, I think the max_t() and min_t() have handled the typechecking thing, 
> maybe we do not need to do it again here.  
> If you have a different opinion, how should we do a typechecking here? Is 
> the following what you expected?
> #define clamp_t(type, val, lo, hi)    \
> ({     type _val = (val);                   \
>         type _lo = (lo);                      \
>         type _hi = (hi);                      \
>        min_t(type, max_t(type, _val, _lo), _hi)
> })

I don't think you understood: I asked for a clamp() to accompany
clamp_t(), just like e.g. max_t() is a less preferred sibling of max().

Jan


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