Re: [Bluez-devel] Elimination of pow() in SBC code

[Marcel Holtmann <marcel@holtmann.org>]

Hi Henryk,

> > the pow() function is the only reason for linking with -lm and it is
> > only used in one place with a limit range of parameters.
> 
> Oh yes, that occurence of pow(2.0, x) is in older code I forgot about.
> (And before -lm was necessary for cos(), too)
> 
> > So what is the range of scale_factor[ch][sb]. From a quick testing a
> > saw that it ranges from 0 - 15. Is this always true? 
> 
> Yes, scale_factor is a 4 bit integer (Table 12.13 of A2DP) and there
> should be no way of getting it bigger. If there was this would be a bug.
> 
> > If yes, then I would use a pre-calculated array for 2^x.
> 
> Isn't 1<<x good enough for that?

stupid me. Of course power of two is done by bitshifting. I committed
the following to the CVS:

	2 << frame->scale_factor[ch][sb]

Regards

Marcel




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