Re: Simple/Fast Algorithm for binary logarithm in C (on ARM7)

On Fri, 11 May 2007 23:02:31 +0200, Tilmann Reh
<tilmannreh@xxxxxxxxxxxxx> wrote:

Jonathan Kirwan schrieb:

You've gotten some responses already, but here's another you might
consider looking at. It's one of the chapters of a book that Analog
used to give away (don't know if they still do) to customers. Great
book. Anyway, this chapter covers the logarithm for the ADSP-21xx DSP
processor, but it includes a good description about the whys and
wherefores as well as a coded example (which requires a little bit of
learning of the isntruction set if you want to understand each and
every step of the code -- but that isn't too hard.) Here is the
chapter:

http://www.analog.com/UploadedFiles/Associated_Docs/727652249Chapter_4.pdf

Thanks for that link, Jonathan. I had also found it doing one more
internet search this afternoon, but didn't yet find the time to look at
it more deeply (which I'll surely do, however).

I used that routine, with modifications I made, in an application I
wrote (and is still in use today) back in 1990, or so. It's worked
very well. If you have further questions about the concepts there,
feel free to ask. I can address the mathematical treatment to get
there as well as the implementation details.

Jon
.

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