Re: hash function optimization

[James W. W. <ja...@wr...>]

Dair Grant <da...@re...> wrote:

>This was actually one of the changes that came up when looking at
>Roger's changes to the way instance data is found; the existing hash
>function turned out to be really quite suboptimal (use of % generates an
>expensive divide), and so replacing that was definitely a good idea.
>
>I actually had it changed here too, but never got round to checking it
>in - thanks! :-)

Did you change it the same way?  I didn't get rid of the % operation 
entirely, just reduced from 4 times to one.  If we could require that 
the table size is always a power of 2, then we could replace x % 
tableSize by x & (tableSize - 1).  Do you suppose that would be 
worthwhile?
-- 
   James W. Walker, ScriptPerfection Enterprises, Inc.
   <http://www.write-brain.com/>