[Mplayer-users] a suggestion ..
p_l at tfz.net
Mon Jul 9 18:51:54 CEST 2001
On Mon, Jul 09, 2001 at 10:28:19PM +0900, Yang Hyun wrote:
> I found that functions of "idtc_mmx.c" was called many time.
> I have heard Macro Functions are better than Inline Functions in Speed .
> I think the functions of "idtc_mmx.c" is easy to be chaged to Macro func.
> eg) block_copy,block_add function
That's not always true: if your macro is quite big you may run slower because
of cache effects. inline is juste an advice given to gcc, IIRC:
when you declare a function "inline", gcc tries to inline it if it can and
"thinks" the inlining is valuable. If inlined, the output should be
(is ?) very close to the output you would have got if it had been a macro.
> and there are many codes which must be chaged to "shift operator" .
> eg) DCT_offset = stride * 8;
> -> DCT_offset = stride << 3;
That may have been true in the past but nowadays, most compiler tend to optimize
such constructions (multiplication by a constant) by correctly generating a bitshift
or more efficient code if it's not a 2^n.
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