Found unsupported type in switch expression; switch expression must be of discrete type

Tobis_stelzer - 2021-09-04T12:18:51+00:00

Question: Found unsupported type in switch expression; switch expression must be of discrete type

Hello,   I use a Matlab Function block as state machine in my Simulink module. Everything works, except the RTL Code generation in the HDL Workflow Advisor. At this point I get the following error: Found unsupported type in switch expression; switch expression must be of discrete type, Function 'MNIST_CNN/MAXPOOL_BANK_20/CONTROL/MATLAB Function' (#1650.355.365), line 13, column 9.   My Matlab Code looks like this:   function [hStart,hEnd,valid,reset,enable] = maxpool_fsm(hStart_in,hEnd_in,valid_in) %states: ready = 0; vector = 1; matrix = 2; wait_for_next_line=3; % using persistent keyword to model state registers in hardware persistent curr_state; if isempty(curr_state) curr_state = ready; end % switch to new state based on the value state register switch (curr_state) case ready, if (hStart_in==true && valid_in==true) curr_state=vector; valid=false; reset=true; enable=true; hEnd=false; hStart=true; else curr_state=ready; valid=false; reset=true; enable=true; hEnd=false; hStart=false; end case vector, if (valid_in == true && hEnd_in==true) curr_state=wait_for_next_line; valid=true; reset=false; enable=true; hEnd=true; hStart=false; elseif (valid_in == true) curr_state=matrix; valid=true; reset=false; enable=true; hEnd=false; hStart=false; else curr_state=vector; valid=false; reset=true; enable=true; hEnd=false; hStart=false; end case matrix, if (hEnd_in==true) curr_state=wait_for_next_line; valid = false; reset = false; enable = false; hEnd=true; hStart=false; elseif (valid_in==true) curr_state=vector; valid = false; reset = true; enable = true; hEnd=false; hStart=false; else curr_state=matrix; valid=false; reset=false; enable=false; hEnd=false; hStart=false; end case wait_for_next_line, if (hEnd_in==true) curr_state=ready; valid = false; reset=false; enable = false; hEnd=false; hStart=false; else curr_state=wait_for_next_line; valid = false; reset=false; enable = false; hEnd=false; hStart=false; end otherwise, valid = false; reset=false; enable = false; hEnd=false; hStart=false; end During compilation and simulation everything works. I have no clue, where the error is. In the Model Advisor the following error appeas:   Failed The model contains constructs that are unsupported for HDL code generation.   Error using hdlcoder.pirctx/invokeBackEnd   The model contains constructs that are unsupported for HDL code generation.   Error in slhdlcoder.HDLCoder/makehdl   Error in slhdlcoder.HDLCoder/makehdlturnkey   Error in downstream.DownstreamIntegrationDriver/runIPCoreCodeGen   Error in generateIPCore   Error in Simulink.ModelAdvisor/executeCheckCallbackFct   Error in Simulink.ModelAdvisor/run   Error in Simulink.ModelAdvisor/runCheck   Error in ModelAdvisor.Node/runTaskAdvisor   Error in ModelAdvisor.Node.runtohere>runToBreakpoint   Error in ModelAdvisor.Node.runtohere  

Related Questions

Expert Answer

Prashant Kumar answered . 2025-11-20

I solved the issue by not declaring the state variable as persistent, but instead using a delay outside the matlab function block:

 

function [hStart,hEnd,valid,reset,enable,curr_state_out] = maxpool_fsm(curr_state_in,hStart_in,hEnd_in,valid_in)
%states:
ready = uint8(0);
vctr = uint8(1);
mtrx = uint8(2);
wait_for_next_line=uint8(3);
% using persistent keyword to model state registers in hardware
%persistent curr_state;
curr_state_out=uint8(0);
if isempty(curr_state_out)
    curr_state_out = ready;   
end
% switch to new state based on the value state register
switch(curr_state_in)
    case ready,        
        if (hStart_in==true && valid_in==true)
            curr_state_out=vctr;
            valid=false;
            reset=true;
            enable=true;
            hEnd=false;
            hStart=true;
        else
            curr_state_out=ready;
            valid=false;
            reset=true;
            enable=true;
            hEnd=false;
            hStart=false;
        end
        
    case vctr,        
        if (valid_in == true && hEnd_in==true)
            curr_state_out=wait_for_next_line;
            valid=true;
            reset=false;
            enable=true;
            hEnd=true;
            hStart=false;
        elseif (valid_in == true)
            curr_state_out=mtrx;
            valid=true;
            reset=false;
            enable=true;
            hEnd=false;
            hStart=false;
        else
            curr_state_out=vctr;
            valid=false;
            reset=true;
            enable=true;
            hEnd=false;
            hStart=false;
        end
        
    case mtrx,       
        if (hEnd_in==true)
            curr_state_out=wait_for_next_line;
            valid = false;
            reset = false;
            enable = false;
            hEnd=true;
            hStart=false;
        elseif (valid_in==true)
            curr_state_out=vctr;
            valid = false;
            reset = true;
            enable = true;
            hEnd=false;
            hStart=false;
        else
            curr_state_out=mtrx;
            valid=false;
            reset=false;
            enable=false;
            hEnd=false;
            hStart=false;
        end
        
   
    case wait_for_next_line,
        if (hEnd_in==true)
            curr_state_out=ready;
            valid = false;
            reset=false;
            enable = false;
            hEnd=false;
            hStart=false;
        else
            curr_state_out=wait_for_next_line;
            valid = false;
            reset=false;
            enable = false;
            hEnd=false;
            hStart=false;
        end
    otherwise,
        valid = false;
        reset=false;
        enable = false;
        hEnd=false;
        hStart=false;
        
end

Not satisfied with the answer ?? ASK NOW