[MPlayer-dev-eng] [PATCH] Make mp3lib SIMD optimizations work on AMD64, Part 5

[Zuxy Meng]

Hi,

2007/5/25, Reimar Döffinger <Reimar.Doeffinger at stud.uni-karlsruhe.de>:
> Hello,
> On Fri, May 25, 2007 at 09:24:58PM +0800, Zuxy Meng wrote:
> > 2007/5/25, Reimar Döffinger <Reimar.Doeffinger at stud.uni-karlsruhe.de>:
> > > > -static void make_decode_tables(long scaleval)
> > > > +static void make_decode_tables()
> > > >  {
> > > > -  int i,j,k,kr,divv;
> > > > +  int i,j,k,kr,divv,scaleval=32768;
> > >
> > > This is unrelated and also completely useless since a static function
> > > that is used in only one place will be inlined anyway.
> >
> > What I feel uncomfortable is the file scope static variable
> > 'outscale'. An immediate or even a constant local variable looks
> > better to me. I had to admit it's more an aesthetic matter.
>
> And still unrelated ;-). And changing the static variable into a define
> and using that as parameter seems like a better solution to me than
> removing the parameter.

OK. Will be in a seperate patch.

> Or if you remove the parameter, adjust the code to it. At least the
> first scaleval = -scaleval; is then completely useless.
> And if you decide to optimize that function, get rid of the useless
> divisions (e.g. i % 32).
>
> > > In addition it is wrong since "static void make_decode_tables()" !=
> > > "static void make_decode_tables(void)"
> >
> > Really? I know that () isn't equivalent to (void) in declarations but
> > is (void) needed even in definitions?
>
> Why should it be treated different depending on whether there is a
> function body directly below it or not?

Because the standard says so (C99 6.7.5.3.14) :-)
An identifier list declares only the identifiers of the parameters of
the function. An empty list in a function declarator that is part of a
definition of that function specifies that the function has no
parameters. The empty list in a function declarator that is not part
of a definition of that function specifies that no information about
the number or types of the parameters is supplied.
-- 
Zuxy
Beauty is truth,
While truth is beauty.
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