coder.reservedName

Define the MATLAB function callfoo that declares a global variable g, calls an external C function foo, and returns the sum of g and the value that foo returns. Insert the coder.reservedName('g') directive to instruct the code generator to not use the identifier g in the generated code.

function u = callfoo(n)  %#codegen
% Reserve 'g' for use in the C function foo
coder.reservedName('g');

global g
u = int32(0);

coder.updateBuildInfo('addSourceFiles','foo.c');
coder.cinclude('foo.h');

u = coder.ceval('foo', n);
u = u + g;
end

Declare the function foo in the C header file foo.h:

int foo(int x);

Define the function foo in the C source file foo.c. This function accepts an integer input and returns the factorial of that integer.

#include <stdio.h>
#include <stdlib.h>
#include "foo.h"

int foo(int x)
{
    int count;
    int g = 1;
    for (count = 1;count <= x;count++)
    {
        g = g*count;
    }
    
    return (g);
}

Generate a static library for callfoo. Specify the input as a scalar 32-bit integer.

codegen -config:lib -global {'g', int32(2)} callfoo -args {int32(0)} -report

Inspect the generated header file callfoo_data.h. The name of the global variable has been changed to b_g.

extern int b_g;