BitArray/BitFields - Review

[Don Clugston]

On 29/07/12 23:36, bearophile wrote:
> Era Scarecrow:

 >>> Another commonly needed operation is a very fast bit count. There 
are very refined algorithms to do this.
>
>>  Likely similar to the hamming weight table mentioned in TDPL.
>> Combined with the canUseBulk I think I could make it fairly fast.
>
> There is lot of literature about implementing this operation
> efficiently. For the first implementation a moderately fast (and short)
> code is probably enough. Later faster versions of this operation will go
> in Phobos, coming from papers.

See bug 4717. On x86, even on 32 bits you can get close to 1 cycle per 
byte, on 64 bits you can do much better.