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Include MATLAB Code as Comments in Generated Code

If you have Simulink® Coder™ , you can include MATLAB® source code as comments in the code generated for a MATLAB Function block. Including this information in the generated code enables you to:

  • Correlate the generated code with your source code.

  • Understand how the generated code implements your algorithm.

  • Evaluate the quality of the generated code.

When you select the MATLAB source code as comments parameter, the generated code includes:

  • The source code as a comment immediately after the traceability tag. When you enable traceability and generate code for ERT targets (requires Embedded Coder®), the traceability tags are hyperlinks to the source code. For more information, see Use Traceability in MATLAB Function Blocks (Embedded Coder).

    For examples and information on the location of the comments in the generated code, see Location of Comments in Generated Code (Embedded Coder).

  • The function help text in the function body in the generated code. The function help text is the first comment after the MATLAB function signature. It provides information about the capabilities of the function and how to use it.

    Note

    With Embedded Coder, you can also include the function help text in the generated code function banner. For more information, see Include MATLAB User Comments in Generated Code (Embedded Coder).

Include MATLAB Code as Comments in the Generated Code

To include MATLAB source code as comments in the code generated for a MATLAB Function block:

  1. On the C Code tab, click Configuration Parameters.

  2. In the Code Generation > Comments pane, select MATLAB source code as comments and click Apply.

Location of Comments in Generated Code

The comments containing the source code appear after the traceability tag in the generated code as follows. 

/* '<S2>:1:18' for y = 1 : 2 : (HEIGHT-4) */
Selecting the Stateflow object comments parameter generates the traceability comment '<S2>:1:18'. Selecting the MATLAB source code as comments parameter generates the for y = 1 : 2 : (HEIGHT-4) comment.

Straight-Line Source Code

The comment containing the source code precedes the generated code that implements the source code statement. This comment appears after comments that you add, which precede the generated code. The comments are separated from the generated code because the statements are assigned to function outputs.

MATLAB Code

function [x y] = straightline(r,theta)
%#codegen
% Convert polar to Cartesian
x = r * cos(theta);
y = r * sin(theta);

Commented C Code

/* MATLAB Function 'straightline': '<S1>:1' */
        /*  Convert polar to Cartesian */
        /* '<S1>:1:4' x = r * cos(theta); */
        /* '<S1>:1:5' y = r * sin(theta); */
        straightline0_Y.x = straightline0_U.r * cos(straightline0_U.theta);
      
        /* Outport: '<Root>/y' incorporates:
         *  Inport: '<Root>/r'
         *  Inport: '<Root>/theta'
         *  MATLAB Function Block: '<Root>/straightline'
         */
        straightline0_Y.y = straightline0_U.r * sin(straightline0_U.theta);

If Statements

The comment for the if statement immediately precedes the code that implements the statement. This comment appears after comments that you add, which precede the generated code. The comments for the elseif and else clauses appear immediately after the code that implements the clause and before the code generated for statements in the clause.

MATLAB Code

function y = ifstmt(u,v) 
%#codegen
if u > v
    y = v + 10;
elseif u == v
    y = u * 2;
else
    y = v - 10;
end

Commented C Code

/* MATLAB Function 'MLFcn': '<S1>:1' */
        /* '<S1>:1:3' if u > v */
        if (MLFcn_U.u > MLFcn_U.v) {
          /* Outport: '<Root>/y' */
          /* '<S1>:1:4' y = v + 10; */
          MLFcn_Y.y = MLFcn_U.v + 10.0;
        } else if (MLFcn_U.u == MLFcn_U.v) {
          /* Outport: '<Root>/y' */
          /* '<S1>:1:5' elseif u == v */
          /* '<S1>:1:6' y = u * 2; */
          MLFcn_Y.y = MLFcn_U.u * 2.0;
        } else {
          /* Outport: '<Root>/y' */
          /* '<S1>:1:7' else */
          /* '<S1>:1:8' y = v - 10; */
          MLFcn_Y.y = MLFcn_U.v - 10.0;

For Statements

The comment for the for statement header immediately precedes the generated code, which implements the header. This comment appears after comments that you add, which precede the generated code.

MATLAB Code

function y = forstmt(u) 
%#codegen
y = 0;
for i=1:u
    y = y + 1;
end

Commented C Code

/* MATLAB Function 'MLFcn': '<S1>:1' */
        /* '<S1>:1:3' y = 0; */
        rtb_y = 0.0;
      
        /* '<S1>:1:5' for i=1:u */
        for (i = 1.0; i <= MLFcn_U.u; i++) {
          /* '<S1>:1:6' y = y + 1; */
          rtb_y++;

While Statements

The comment for the while statement header immediately precedes the generated code, which implements the statement header. This comment appears after comments that you add, which precede the generated code.

Switch Statements

The comment for the switch statement header immediately precedes the generated code that implements the statement header. This comment appears after comments that you add that precede the generated code. The comments for the case and otherwise clauses appear immediately after the generated code that implements the clause, and before the code generated for statements in the clause.

Include MATLAB User Comments in Generated Code

MATLAB user comments include the function help text and other comments. The function help text is the first comment after the MATLAB function signature. It provides information about the capabilities of the function and how to use it. You can include the MATLAB user comments in the code generated for a MATLAB Function block.

  1. On the C Code tab, click Configuration Parameters.

  2. In the Code Generation > Comments pane, select MATLAB user comments (Embedded Coder) and click Apply.

Limitations of MATLAB Source Code as Comments

For including MATLAB source code as comments, the MATLAB Function block has these limitations :

  • You cannot include MATLAB source code as comments for:

    • MathWorks® toolbox functions

    • P-code

    • Simulation targets

    • Stateflow® Truth Table blocks

  • The appearance or location of comments can vary depending on these conditions:

    • Comments might still appear in the generated code even if the implementation code is eliminated, for example, due to constant folding.

    • Comments might be eliminated from the generated code if a complete function or code block is eliminated.

    • For certain optimizations, the comments might be separated from the generated code.

    • The generated code includes legally required comments from the MATLAB source code, even if you do not choose to include source code comments in the generated code.

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