[CELT-dev] Bitrev for FFT

Jean-Marc Valin
Thu, 03 Mar 2011 12:00:08 -0000

I'd be *very* surprised if your DSP's bitrev instruction worked for
sizes that are non-powers of two, so you should probably stick with the
table.

	Jean-Marc

On 11-03-03 06:42 AM, Riccardo Micci wrote:
>
> Hi,
> Our DSP has a built-in bitrev instruction so we're exploring the
> possibility of calculating the bitrev every time instead of filling the
> table during initialisation, hence saving some memory.
>
> Our frame size is fixed to 320 samples. The two FFTs sizes for normal
> block and short block are 160 and 40 respectively. It's not really
clear
> how the function "compute_bitrev_table" calculates the values.
> Could you quickly explain the idea behind the function so we can try to
> implement it on the fly?
>
> Regards
> Riccardo
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> Riccardo Micci
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