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.

[Alex Ionescu]

I'm concerned about code duplication.

Why can't our intrinsic header be used on host machines???

On 2009-12-07, at 11:16 PM, Timo Kreuzer wrote:

>   
>  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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> > > >  
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> > >   
> >  
> >  Best regards,
> >  Alex Ionescu
> >  
> >  
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> >   
>  
>  
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Best regards,
Alex Ionescu