The following example shows how to use local functions in MATLAB®, so that each execution of a local function corresponds to a separate hardware module in the generated HDL code.
This example demonstrates best practices for writing local functions in MATLAB code that is suitable for HDL code generation.
If your MATLAB code executes a local function multiple times, the generated HDL code does not necessarily instantiate multiple hardware modules. Rather than instantiating multiple hardware modules, multiple calls to a function typically update the state variable.
If you want the generated HDL code to contain multiple hardware modules corresponding to each execution of a local function, specify two different local functions with the same code but different function names. If you want to avoid code duplication, consider using System objects to implement the behavior in the function, and instantiate the System object™ multiple times.
If you want to specify a separate HDL file for each local function in the MATLAB code, in the Workflow Advisor, on the Advanced tab in the HDL Code Generation section, select Generate instantiable code for functions .
This function creates two counters and adds the output of these
counters. To create two counters, there are two local functions with
The main method calls each of these local functions once. If the function
were to call the
counter function twice, separate
hardware modules for the counters would not be generated in the HDL
%#codegen function total_count = mlhdlc_two_counters(a,b) %This function contains two different local functions with identical %counters and calls each counter once. total_count1=counter(a); total_count2=counter2(b); total_count=total_count1+total_count2; function count = counter(enable_ctr) %four bit synchronous up counter %persistent variable for the state persistent count_val; if isempty(count_val) count_val = 0; end %counting up if enable_ctr count_val=count_val+1; end %limit from four bits if count_val>15 count_val=0; end count=count_val; function count = counter2(enable_ctr) %four bit synchronous up counter %persistent variable for the state persistent count_val; if isempty(count_val) count_val = 0; end %counting up if enable_ctr count_val=count_val+1; end %limit from four bits if count_val>15 count_val=0; end count=count_val;