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