On Tue, Nov 14, 2006 at 05:33:09PM +0100, Dave Long wrote: > A couple of years ago* I'd wondered about gray-coded PC increments.
Do you know how to implement a local-bitflip (linear, or slightly staggered registers) Gray code with the shallowest number of gates? > Well, the DSP people haven't gone that far, but they do offer the > option of bit-reversed autoincrementing index registers. By counting > left-to-right (x000, x100, x010, x110, x001, x101, x011, x111, x000...) > one can get various power-of-two circular buffers "for free". > > That may seem like a lot of trouble to save a mask op, but there's a > good market reason to provide the feature: bit reversal simplifies > twiddling FFT butterflies. This is very old (1994-1996), but you might like http://leitl.org/oldcontent/ui22204/.html/txt/8uliw.txt -- Eugen* Leitl <a href="http://leitl.org";>leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE
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