MATLAB HDL-Coder: Expression could not be reduced to a constant.

I am trying to pass a struct hwconst into a MATLAB function.

function [out] = function_hdl(in, hwconst)

That function I want to translate into Verilog code using HDL-Coder. hwconst contains a field lfsrWidth. I am then using this field in the MATLAB function as follows:

WD_lfsr = coder.const(hwconst.lfsrWidth);

However, that line gives me an error during building: "Expression could not be reduced to a constant." I guess it's because lfsrWidth is not defined as a constant, see below. That's because the option for that is not there. How to use a structure with hardware constants properly with HDL Coder?

Answer 1

[Kiran Kintali]

Is hwconst an input variable (creates hardware interface pins) or just a non-tuanble constant parameter passed into the design from the testbench. If it is a constant parameter you need to right click in the GUI for hwconst and define it a constant value.

Here are some examples on how to do this via command line workflows.

https://www.mathworks.com/help/hdlcoder/ug/handling-constants-in-hdl-and-high-level-synthesis-code-generation.html

This example shows how to pass / load constants

>> mlhdlc_demo_setup('comms_data_packet')