codegen - Generate C/C++ code from MATLAB code

Syntax

Description

codegen options files fcn_1 args... fcn_n args translates the MATLAB^® functions fcn_1 through fcn_n to a C/C++ static or dynamic library, executable, or to a MEX function. Optionally, you can specify custom files to include in the build. codegen applies the options to all functions fcn_1 through fcn_n. It applies args to the preceding function only (fcn_n). If you specify C++, MATLAB Coder™ wraps the C code into .cpp files so that you can use a C++ compiler and interface with external C++ applications. It does not generate C++ classes.

codegen project_name generates output for the MATLAB Coder project project_name. codegen generates a MEX function, C/C++ static or dynamic library or C/C++ executable depending on the project settings defined for project_name.

Each time codegen generates the same type of output for the same code or project, it removes the files from the previous build. If you want to preserve files from a previous build, copy them to a different location before starting another build.

Input Arguments

codegen/target/fcn_name. 

Examples

Generate a MEX function from a MATLAB function that is suitable for code generation.

1. Write a MATLAB function, coderand, that generates a random scalar value from the standard uniform distribution on the open interval (0,1).

   function r = coderand() %#codegen
   % The directive %#codegen indicates that the function
   % is intended for code generation
   r = rand();

2. Generate and run the MEX function. By default, codegen names the generated MEX function coderand_mex.

   codegen coderand
   coderand_mex

Generate C executable files from a MATLAB function that is suitable for code generation. Specify the main C function as a configuration parameter.

1. Write a MATLAB function, coderand, that generates a random scalar value from the standard uniform distribution on the open interval (0,1).

   function r = coderand() %#codegen
   r = rand();

2. Write a main C function, c:\myfiles\main.c, that calls coderand.

   /*
   ** main.c
   */
   #include <stdio.h>
   #include <stdlib.h>
   #include "coderand.h"
   
   int main()
   {
       coderand_initialize();
       
       printf("coderand=%g\n", coderand());
       
       coderand_terminate();
       
       return 0;
   }

3. Configure your code generation parameters to include the main C function, then generate the C executable.

   cfg = coder.config('exe')
   cfg.CustomSource = 'main.c'
   cfg.CustomInclude = 'c:\myfiles'
   codegen -config cfg coderand

   codegen generates a C executable, coderand.exe, in the current folder, and supporting files in the default folder, codegen/exe/coderand.

   This example shows how to specify a main function as a parameter in the configuration object coder.CodeConfig. Alternatively, you can specify the file containing main() separately on the command line. You can use a source, object, or library file.

Generate C library files in a custom folder from a MATLAB function with inputs of different classes and sizes. The first input is a 1-by-4 vector of unsigned 16-bit integers. The second input is a double-precision scalar.

1. Write a MATLAB function, mcadd, that returns the sum of two values.

   function y = mcadd(u,v) %#codegen
   y = u + v;

2. Generate the C library files in a custom folder mcaddlib using the -config:lib option.

   codegen -d mcaddlib -config:lib  mcadd -args {zeros(1,4,'uint16'),0} 

Generate C library files from a MATLAB function that takes a fixed-point input.

1. Write a MATLAB language function, mcsqrtfi, that computes the square root of a fixed-point input.

   function y = mcsqrtfi(x) %#codegen
   y = sqrt(x);

2. Define numerictype and fimath properties for the fixed-point input x and generate C library code for mcsqrtfi using the -config:lib option.

   T = numerictype('WordLength',32, ...
                   'FractionLength',23, ...
                   'Signed',true)
   F = fimath('SumMode','SpecifyPrecision', ...
              'SumWordLength',32, ...
              'SumFractionLength',23, ...
              'ProductMode','SpecifyPrecision', ...
              'ProductWordLength',32, ...
              'ProductFractionLength',23)
   % Define a fixed-point variable with these
   %  numerictype and fimath properties
   myfiprops = {fi(4.0,T,F)}
   codegen -config:lib mcsqrtfi -args myfiprops 

   codegen generates C library and supporting files in the default folder, codegen/lib/mcsqrtfi.

Specify global data at the command line.

1. Write a MATLAB function, use_globals, that takes one input parameter u and uses two global variables AR and B.

   function y = use_globals(u)
   %#codegen
   % Turn off inlining to make 
   % generated code easier to read
   coder.inline('never');
   global AR;
   global B;
   AR(1) = u(1) + B(1);
   y = AR * 2;

2. Generate a MEX function. By default, codegen generates a MEX function named use_globals_mex in the current folder. Specify the properties of the global variables at the command line using the -globals option. Specify that input u is a real, scalar, double, using the -args option.

   codegen -globals {'AR', ones(4), 'B', [1 2 3 4]} ...
   	use_globals -args {0}

Alternatively, you can initialize the global data in the MATLAB workspace. At the MATLAB prompt, enter:

global AR B;
AR = ones(4);
B=[1 2 3];

Compile the function to generate a MEX file named use_globalsx.

codegen use_globals -args {0}

Generate output for a MATLAB Coder project, test_foo.prj, that includes one file, foo.m, and has it output type set to C/C++ Static Library.

codegen test_foo.prj

codegen generates a C library, foo, in the codegen\lib\foo folder.

Generate a MEX function for a function, displayState that has an input parameter that is an enumerated type.

1. Write a function, displayState, that uses enumerated data to activate an LED display, based on the state of a device. It lights a green LED display to indicate the ON state and lights a red LED display to indicate the OFF state.

   function led = displayState(state)
   %#codegen
   
   if state == sysMode.ON
       led = LEDcolor.GREEN;
   else
       led = LEDcolor.RED;
   end

2. Define an enumeration LEDColor. On the MATLAB path, create a file named 'LEDColor' containing:

   classdef(Enumeration) LEDcolor < int32
       enumeration
           GREEN(1),
           RED(2),
       end
   end

3. Create a coder.EnumType object using a value from an existing MATLAB enumeration.

   1. Define an enumeration sysMode. On the MATLAB path, create a file named 'sysMode' containing:

      classdef(Enumeration) sysMode < int32
        enumeration
          OFF(0)
          ON(1)
        end
      end

   2. Create a coder.EnumType object from this enumeration.

      t = coder.typeof(sysMode.OFF);

4. Generate a MEX function for displayState.

   codegen  displayState -args {t}

Alternatives

Use the coder function to create a MATLAB Coder project. The project provides a user interface that facilitates adding MATLAB files, defining input parameters, and specifying build parameters.

See Also

coder | coder.EnumType | coder.runTest | coder.typeof | fi | fimath | mex | numerictype

Tutorials

• Generating C Code from MATLAB Code at the Command Line
• Generating C Code from MATLAB Code Using the MATLAB Coder Project Interface
• Generating MEX Functions from MATLAB Code at the Command Line

How To

• Preparing MATLAB Code for C/C++ Code Generation
• Generating C/C++ Code from MATLAB Code
• Primary Function Input Specification
• Specifying a Language for Code Generation
• Paths and File Infrastructure Setup
• Code Generation for Global Data
• Synchronizing Global Data with MATLAB
• Code Generation for More Than One Entry-Point MATLAB Function

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• MATLAB
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