[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