Generating C Code Using emlc

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Prerequisites for Generating C Code Contents of the Example Build Script Using the Example Build Script Comparing the Generated C Code to Original M-Code Next Task

Prerequisites for Generating C Code

To use emlc, you must install Real-Time Workshop and its prerequisite products:

• MATLAB

• Simulink

• C compiler (a default compiler is supplied with MATLAB)

For instructions on installing and setting up a C compiler, see Setting Up the C Compiler in the Real-Time Workshop User's Guide.

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Contents of the Example Build Script

For this exercise, you use the build script emldemo_lms_build_02_lib.m.

emldemo_lms_build_02_lib.m contains:

close all;
clear all;
clc;

N = 73113;

emlc    emldemo_lms_02 ...
  -eg { zeros(N,1) zeros(N,1) } ...
  -report ...
  -c ...   
  -T rtw:lib

where:

• clear all removes all variables, functions, and MEX-files from memory, leaving the workspace empty. It also clears all breakpoints.

  Note   Remove the clear all command from the build scripts if you want to preserve break points for debugging.

• emlc opens the file emldemo_lms_02 and automatically translates the Embedded MATLAB compliant M-code into C source code.

  See Converting MATLAB Code to C Code in the Real-Time Workshop User's Guide for more information.

• The -report option instructs emlc to generate a compilation report.

   Best Practice — Generating a Compilation Report

  Use the -report option to generate an HTML report with hyperlinks to C source files and header files automatically generated from the MATLAB function. This information simplifies finding sources of error messages and aids understanding of type propagation rules. If this option is not specified, emlc generates a report only if there are compilation messages. See -report Generate Compilation Report for more information.

• The -c option instructs emlc to generate code only, without compiling the code to an object file.

   Best Practice — Generating C Code Only During Development Phase

  During the development cycle, use the -c option for generating C code without building an executable. This option enables you to iterate rapidly between modifying M-code and generating C code. See -c Generate Code Only for more information.

• The -T option instructs emlc to generate embeddable C code suitable for targeting a shared library instead of generating the default MEX function. See emlc in the Real-Time Workshop Reference for more information.

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Using the Example Build Script

To generate C code:

1. Set your MATLAB current folder to the folder that contains your files for this tutorial.

2. Type emldemo_lms_build_02_lib at the MATLAB command prompt.

   MATLAB processes the build file and outputs the message:

   Compilation successful: Open compilation report.

3. To view the compilation report, click the Open compilation report. link.

   The Embedded MATLAB Compilation Report appears.

   

4. Click the C-code tab to display the list of generated C files.

   

5. To view the generated C code, click the link to the target source file, for example, emldemo_lms_02.c.

   The file appears in the Embedded MATLAB Coder window.

   

   Note   The generated C code is in folder\emcprj\rtwlib\emldemo_lms_02, where folder is the folder that contains your tutorial files.

6. Close the error report and emldemo_lms_02.c file.

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Comparing the Generated C Code to Original M-Code

To compare your generated C code to the original M-code, open the C file, emldemo_lms_02.c, and the M-file, emldemo_lms_02.m, in the MATLAB Editor. Use the left/right tile feature to view the files side by side by selecting Window > Left/Right Tile. (See Comparing C Code and M-Code Using Tiling in the MATLAB Editor for more information.)

You can easily compare the generated C code to your original M-code. In the generated C code:

• Your function name is unchanged.

• Your comments are preserved in the same position.

• Your variable names are prefixed with eml_.

  Note   If a variable in your M-code is set to a constant value, it does not appear as a variable in the generated C code. Instead the generated C code contains the actual value of the variable. For example, the variable L is set to 32 in the M-code, so L does not appear in the generated C code, the value 32 appears wherever L is used.

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Next Task

You have generated C code for your Embedded MATLAB compliant M-code. You are ready to begin the next task in this tutorial, Elaborating Your Algorithm for Embedded Implementation.

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Generating C Code

Elaborating Your Algorithm for Embedded Implementation

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