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Problem in using cfft function

Question asked by Senthil on Dec 14, 2010
Latest reply on Dec 15, 2010 by Senthil

Hi all,

      I am trying to implement 32 Point FFT using VDSP in-built function as reference. First I used cfftf_simd.asm residing at “C:\ Program Files\Analog Devices\VisualDSP 5.0\214xx\lib\src\libdsp_src\” to implement 128 point FFT.


void cfftf            (float data_real[], float data_imag[],

             float temp_real[]. float temp_imag[],

             const float twid_real[],

const float twid_imag[],

             int n);


But from the comments provided in the file it is found that 32 point is not possible with that routine. So we used routine in cfft_simd.asm attached herewith,

complex_float *cfft32    (complex_float dm input[],

                                                  complex_float dm output[]);


Passing arguments for that routine is input buffer and output buffer address. In the document it is said to keep both buffer of size ‘N’ where N is the FFT points.


In that case whether input buffer should be interleaved with real and imaginary values. Then what we will get in the output buffer.


Expecting a quick response. Thanks in advance.