Generation of C code from simulink

I am trying to get a C code for the peaking IIR filter, but I am getting the following error in MATLAB Code Report Viewer.I am attaching the MATLAB code below .Please help me to debug this error .Any help would be appreciated

function Hd = Filter1_150_matlab
%FILTER1_150_MATLAB Returns a discrete-time filter object.

% MATLAB Code
% Generated by MATLAB(R) 9.4 and DSP System Toolbox 9.6.
% Generated on: 26-Mar-2019 16:44:54

% IIR Peaking filter designed using the IIRPEAK function.

% All frequency values are in Hz.
Fs = 1000;  % Sampling Frequency

Fpeak = 150;  % Peak Frequency
Q     = 100;  % Q-factor
Apass = 1;    % Bandwidth Attenuation

BW = Fpeak/Q;

% Calculate the coefficients using the IIRNOTCHPEAK function.
[b, a] = iirpeak(Fpeak/(Fs/2), BW/(Fs/2), Apass);
Hd = dsp.IIRFilter( ...
    'Structure', 'Direct form II', ...
    'Numerator', b, ...
    'Denominator', a);
num = [0.0092 0 -0.0092]
den = [1 -1.1648 0.9816]
%Hz1 = filt(num,den)
%disp(Hz1)

% [EOF]

I am getting following error message

Handle Classes in top-level outputs are not supported in MATLAB Coder. 
Output parameter 'Hd' contains a handle class.

[Walter Roberson]

What error message are you observing?

[Walter Roberson]

Are you asking Coder to compile this as your main routine, or is there a different main routine that calls this one and you are asking to compile that other routine?

Answer 1

[David Fink]

Based on the error message, Hd (a dsp.IIRFilter) contains a member that is a handle class, which let multiple names refer to the same object.

While handle classes are supported for code generation, as of R2019a, they are not yet supported as inputs or outputs (or data members of inputs or outputs) to entry-point functions (the function name you tell MATLAB Coder to generate code for).

We've made an internal note of your request so we can look at lifting that limitation in the future.

For now, a workaround is to pass non-handle data as output.

Instead of the filter as output, the function could take in input data and output the result of the filter on that data.