[dpdk-stable] [EXT] Re: [PATCH] eal: fix macros to align value
Thomas Monjalon
thomas at monjalon.net
Wed Jun 24 10:30:18 CEST 2020
24/06/2020 10:24, Harman Kalra:
> On Wed, Jun 24, 2020 at 10:13:18AM +0200, Thomas Monjalon wrote:
> > 09/06/2020 21:17, Harman Kalra:
> > > Found an issue while using RTE_ALIGN_MUL_NEAR with an
> > > expression, like as passed in estimate_tsc_freq().
> > > RTE_ALIGN_MUL_FLOOR resulted in unexpected value in the
> > > above function as division has more precedence over
> > > substraction.
> >
> > The only change I see is adding parenthesis around v.
> > Am I right?
>
> Yes, parathesis are required if an expression is passed.
I think the commit log needs to be updated.
I don't see the relation between
"division has more precedence over substraction"
and
"parathesis are required if an expression is passed"
> > > #define RTE_ALIGN_MUL_CEIL(v, mul) \
> > > - (((v + (typeof(v))(mul) - 1) / ((typeof(v))(mul))) * (typeof(v))(mul))
> > > + ((((v) + (typeof(v))(mul) - 1) / ((typeof(v))(mul))) * (typeof(v))(mul))
> > [...]
> > > #define RTE_ALIGN_MUL_FLOOR(v, mul) \
> > > - ((v / ((typeof(v))(mul))) * (typeof(v))(mul))
> > > + (((v) / ((typeof(v))(mul))) * (typeof(v))(mul))
> > [...]
> > > ({ \
> > > typeof(v) ceil = RTE_ALIGN_MUL_CEIL(v, mul); \
> > > typeof(v) floor = RTE_ALIGN_MUL_FLOOR(v, mul); \
> > > - (ceil - v) > (v - floor) ? floor : ceil; \
> > > + (ceil - (v)) > ((v) - floor) ? floor : ceil; \
> > > })
> >
> >
> >
> >
>
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