Re: [ros-dev] [ros-diffs] [tkreuzer] 44464: [RTL] Rewrite the rtl bitmap implementation. The old one was a little .... suboptimal. The new one should outperform the old one by several orders of magnitude, especially RtlFindClearBits that was literally searching bit by bit.

[Timo Kreuzer]

Why should I bother reimplementing the intrinsics yet another time for
different compilers in host headers? and what about compiling on a
non-x86 linux machine? This code is portable and serves it's pupose very
well.
Or are you seriously concerned about the performance?


Alex Ionescu schrieb:
>   So? Use intrinsics anyways.
>
>  Or __builtin_clz...
>
>  On 2009-12-07, at 10:07 PM, Timo Kreuzer wrote:
>
>    
> >   Because this is a host module.
> >
> >  Alex Ionescu wrote:
> >      
> > >   Well why this then? They should be intrinsics...
> > >
> > >  On 2009-12-07, at 8:43 PM, Timo Kreuzer wrote:
> > >
> > >
> > >        
> > > >  >> +unsigned char BitScanForward(ULONG *
> > > > Index, unsigned long Mask)
> > > > >> +{
> > > > >> +    *Index = 0;
> > > > >> +    while (Mask && ((Mask & 1) == 0))
> > > > >> +    {
> > > > >> +        Mask >>= 1;
> > > > >> +        ++(*Index);
> > > > >> +    }
> > > > >> +    return Mask ? 1 : 0;
> > > > >> +}
> > > > >> +
> > > > >> +unsigned char BitScanReverse(ULONG * const Index, unsigned long Mask)
> > > > >> +{
> > > > >> +    *Index = 0;
> > > > >> +    while (Mask && ((Mask & (1 << 31)) == 0))
> > > > >> +    {
> > > > >> +        Mask <<= 1;
> > > > >> +        ++(*Index);
> > > > >> +    }
> > > > >> +    return Mask ? 1 : 0;
> > > > >> +}
> > > > >>
> > > > >>              
> > >  Best regards,
> > >  Alex Ionescu
> > >
> > >
> > >  _______________________________________________
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> > >  Ros-dev(a)reactos.org
> > >  http://www.reactos.org/mailman/listinfo/ros-dev
> > >
> > >
> > >         
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> >       
>  Best regards,
>  Alex Ionescu
>
>
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