In the function addglobals_ex, assign the 'ExportedGlobal' storage class to the global variable myglobalone and the 'ExportedDefine' storage class to the global variable myglobaltwo.

function y = addglobals_ex(x) %#codegen
% Define the global variables.
global myglobalone;
global myglobaltwo;

% Assign the storage classes.
coder.storageClass('myglobalone','ExportedGlobal');
coder.storageClass('myglobaltwo','ExportedDefine');
y = myglobalone + myglobaltwo + x;
end

Create a code configuration object for a library or executable.

cfg = coder.config('dll','ecoder', true);

Generate code. This example uses the -globals argument to specify the types and initial values of myglobalone and myglobaltwo. Alternatively, you can define global variables in the MATLAB^® global workspace. To specify the type of the input argument x, use the -args option.

codegen -config cfg -globals {'myglobalone', 1, 'myglobaltwo', 2} -args {1} addglobals_ex -report

From the initial values of 1 and 2, codegen determines that myglobalone and myglobaltwo have the type double. codegen defines and declares the exported variables myglobalone and myglobaltwo. It generates code that initializes myglobalone to 1.0 and myglobaltwo to 2.0.

To view the generated code for myglobaltwo and myglobalone, click the View report link.

In the function addglobal_im, assign the 'ImportedExtern' storage class to the global variable myglobal.

function y = addglobal_im(x)

% Define the global variable.

global myglobal;

% Assign the storage classes.

coder.storageClass('myglobal','ImportedExtern');
y = myglobal + x;
end

Create a file c:\myfiles\myfile.c that defines and initializes the imported variable myglobal.

#include <stdio.h>

/* Variable definitions for imported variables */ 
double myglobal = 1.0;

Create a code configuration object. Configure the code generation parameters to include myfile.c. For output type 'lib', or if you generate source code only, you can generate code without providing this file. Otherwise, you must provide this file.

cfg = coder.config('dll','ecoder', true);
cfg.CustomSource = 'myfile.c';
cfg.CustomInclude = 'c:\myfiles';

Generate the code. This example uses the -globals argument to specify the type and initial value of myglobal. Alternatively, you can define global variables in the MATLAB global workspace. For imported global variables, the code generation software uses the initial values to determine only the type.

codegen -config cfg -globals {'myglobal', 1} -args {1}  addglobal_im -report

From the initial value 1, codegen determines that myglobal has type double. codegen declares the imported global variable myglobal. It does not define myglobal or generate code that initializes myglobal. myfile.c provides the code that defines and initializes myglobal.

To view the generated code for myglobal, click the View report link.

myglobal is declared as extern in the Variable Declarations section in addglobal_im_data.h.

/* Variable Declarations */
/* Declaration for custom storage class: ImportedExtern */
extern double myglobal;

In the function addglobal_imptr, assign the 'ImportedExternPointer' storage class to the global variable myglobal.

function y = addglobal_imptr(x)

% Define the global variable.

global myglobal;

% Assign the storage classes.

coder.storageClass('myglobal', 'ImportedExternPointer');
y = myglobal + x;
end

Create a file c:\myfiles\myfile.c that defines and initializes the imported global variable myglobal.

#include <stdio.h>

/* Variable definitions for imported variables */
double v = 1.0; 
double *myglobal = &v;

Create a code configuration object. Configure the code generation parameters to include myfile.c. For output type'lib', or if you generate source code only, you can generate code without providing this file. Otherwise, you must provide this file.

cfg = coder.config('dll','ecoder', true);
cfg.CustomSource = 'myfile.c';
cfg.CustomInclude = 'c:\myfiles';

Generate the code. This example uses the -globals argument to specify the type and initial value of the global variable myglobal. Alternatively, you can define global variables in the MATLAB global workspace. For imported global variables, the code generation software uses the initial values to determine only the type.

codegen -config cfg -globals {'myglobal', 1} -args {1} addglobal_imptr -report

From the initial value 1, codegen determines that myglobal has type double. codegen declares the imported global variable myglobal. It does not define myglobal or generate code that initializes myglobal. myfile.c provides the code that defines and initializes myglobal.

To view the generated code for myglobal, click the View report link.

myglobal is declared as extern in the Variable Declarations section in addglobal_imptr_data.h.

/* Variable Declarations */
/* Declaration for custom storage class: ImportedExternPointer */
extern double *myglobal;