[Nottingham] A Little Coding Gem

[Martin]

On 16/11/12 14:32, Nick Leverton wrote:
> On Fri, Nov 16, 2012 at 01:55:02PM +0000, Martin wrote:
>> On 16/11/12 13:08, Nick Leverton wrote:
>> [---]
>>> There are loads of techniques to achieve the sort of bit-twiddling
>>> where you (or at least I) sometimes think "how can I do that neatly"
>>> on Bithacks:
>>> http://graphics.stanford.edu/~seander/bithacks.html
>>
>> Thanks for that, rather good and added to the links page:
>>
>> http://nottingham.lug.org.uk/links
> 
> Thanks, I see even your one is on there, along with its rationale
[---]


And all rather importantly useful:

Bit-reversal permutation
http://en.wikipedia.org/wiki/Bit-reversal_permutation


Bit Reversal and Permutation
http://www.katjaas.nl/bitreversal/bitreversal.html


So how fast are your FFTs?! ;-)


We have had barrel shifters in CPUs for a long time now. Is bit order
reversal a new twist to that to be added as it's own ALU/FPU/GPU
instruction some time?...

Cheers,
Martin


-- 
- ------------------ - ----------------------------------------
-    Martin Lomas    - OpenPGP (GPG/PGP) Public Key: 0xCEE1D3B7
- martin @ ml1 co uk - Import from   hkp://subkeys.pgp.net   or
- ------------------ - http:// ml1 .co .uk/martin_ml1_co_uk.gpg