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Documentation of sub-FFT parameters in DSPLIB

Remco Poelstra
Intellectual 985 points

Hi,

Is there any documentation or explanantion about the last two parameters in the FFT functions?

void DSPF_sp_fftSPxSP (int N, float *ptr_x, float *ptr_w, float *ptr_y, unsigned char *brev, int n_min, int offset, int n_max)

The argument documentation says that 'offset' is some index of a sub-FFT inside the main FFT. What is its use? Does it allow to skip over a zero-added array? Or does it allow to calculate a larger FFT in chunks so it will fit in memory?

Kind regards,

Remco Poelstra

  • 0
    TI__Mastermind 43955 points

    Hi Remco,

    Please mention the version details of the DSPLIB and for which series of devices it belongs to?(For example: Is it for c674x? ).

    You mentioned that you referred some documentation. Please let us know about the name and version of the document you are referring to.

    In general, there are lots of useful documentation about FFT in TI websites. Please go to www.ti.com and search for "FFT" (no quotes)

    Check wether the links below are useful:

    http://processors.wiki.ti.com/index.php/Efficient_FFT_Computation_of_Real_Input

    http://e2e.ti.com/support/dsp/tms320c6000_high_performance_dsps/f/115/t/95526.aspx

     

    Regards,

    Shankari.

     

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  • 0 in reply to Shankari G
    Intellectual 985 points

    Hi,

    Thanks for your answer.

    I'm using a C6748 and my DSPLIB is of version 3_1_1_1.

    I'm referring to the included API reference which is supplied as HTML but it can also be found here:

    http://processors.wiki.ti.com/index.php/C674x_DSPLIB#DSPF_sp_fftSPxSP_.28Mixed_Radix_Forward_FFT_with_Bit_Reversal.29.

    I found the usage of the last two parameters in this document:

    http://www.ti.com/lit/an/spra947a/spra947a.pdf

    Maybe it's a good idea to link to that document from the API reference?

    Kind regards,

    Remco Poelstra