Why do I get this error Code generation does not support display for MATLAB classes. 'dsp.HDLIFFT' is a class. ?

I am trying to call a function, which create dsp.IFFT system object, inside another for HDL Code generation.

My Code: %main function

function [out1,out2] = main(x,y,z)
 %call subfunction 1
out1 = sub1(x);
 %call subfunction 2
out2 = sub2(y,z);
end

subfucntion 2 codecode:

function [yOut,validOut] = HDLIFFT128(yIn,validIn)
persistent ifft128;
if isempty(ifft128)
  ifft128 = dsp.HDLIFFT('FFTLength',128);
end    
[yOut,validOut] = step(ifft128,yIn,validIn);
end

Answer 1

[Walter Roberson]

The connection between your two routines is not clear.

I suspect the problem might be because you have not put semi-colon on the end of your assignments to out1, so you are requesting that the result be displayed. If the result is not numeric then the coder will not know how to display it.

Note that you do not assign to out2 in your main function.

[Pablo Medina]

Thanks!

The semi-colon works. But now I get this error:

The function 'HDLIFFT128' contains persistent variables 'ifft128' and has specialization 'HDLIFFT128_s1' associated with it. Function specializations containing persistent variables are not supported for fixed-point conversion. Consider rewriting your algorithm such that it does not use persistent variables within functions that require specialization.

[Walter Roberson]

I would suggest breaking it up into two pieces, one of which constructs the ifft128 object, and the other of which expects that object to be always input.