Bit counting

Graham Toal gtoal at an-teallach.com
Mon Jul 11 05:29:23 PDT 1994


	Again, if its speed you want, you can't beat look up tables no matter how
	hard you try.

Ray, you've missed the point of some of the explanations; VERY FAST cpu's
as unbelievably fast as long as they are executing *on-chip* - as soon as
they have to go to RAM for a table lookup, they suffer a performance hit
equivalent to executing large amounts of in-line instructions - one array
lookup might be worth 200 straight opcodes.  Hence why an in-line scheme
has to be found for critical inner-loop stuff.  The precise details vary
according to the pipelining and the amount of on-cpu instruction cache.

G
PS We'd seen the Escrow Officer Trading Card skit on t.p.c when it first
was posted a couple of months ago ;-)






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