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]

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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