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Subject: Re: Would you trade 384 Kbyte of memory for a one percent speed increase?

Author: Steven Edwards

Date: 11:28:51 08/22/03

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On August 22, 2003 at 14:14:03, Matthias Gemuh wrote:

>On August 22, 2003 at 13:46:55, Steven Edwards wrote:

>>So, instead of
>>
>>    theHash ^= HashManSqVec[man][source] ^ HashManSqVec[man][target]
>>
>>we have
>>
>>    theHash ^= HashManSqSqVec[man][source][target]

>Don't experts say accessing [][] is just expensive, but accessing [][][] is
>death ?

Note that the lower index spans are a power of two, so a left shift is
sufficient.  In both cases there are two left shifts total.  The second case has
one less eight byte xor and, more importantly, one less eight byte memory fetch.




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