原创 How do I include a C file in my Nios II C++ softwa

C2H doesn’t support generating accelerators from C++ files.?

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There is a work-around which will enable you to call your accelerator(s) from a C++ program which involves moving the functions you wish to accelerate from a C++ source file to a C source file.? Once your functions are in a C source file, the C2H compiler can effectively “see them” and convert them into hardware accelerators.?

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There are some additional steps necessary for mixing C and C++ functions (and files).

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The GNU tool-chain supports the calling of C functions from C++ programs (and vice versa) through a well defined methodology of explicit assertion.? ?The way this works is that, from your C++ program you tell the compiler which functions should be call as?C?functions- instead of C++.? This operation is done through the use of the?extern “C”syntax within the C++ source file.

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Some examples of the?extern “C”?syntax in action are as follows:

1. Calling C function from C++ program

Setup:? You have a function?void bar(void), which lives in C source file “bar.c” that you want to call from the C++ source file “foo.cpp”.

Solution:? Add this to the top of “foo.cpp”-??

????????????????extern “C”void foo(void);

2. Calling C functions from C++ program

Setup:? A collection of functions which lives in C source file “bar.c” that you want to call from the C++ source file “foo.cpp”.

Solution:? Simply add braces around the group of functions at the top of the extern statement in “foo.cpp”-??

????????????????extern “C” {

void foo(void);

int foo2(int number);

int foo3(int number1, int number2);

}

3. Calling a C header from a C++ program

Setup: You have a whole collection of C functions (or a library) in a file called “bar.c” that you want to call from your C++ program “foo.c”, and you really don’t want to list them individually through procedure #2 (above).? You do have a header file for “bar.c” called “bar.h” which declares the interface to the functions.

Solution: The extern statement also works for header files… In the file “foo.cpp”, use the extern statement to add the header file-

??????????????? extern “C” {

??????????????????????????????? #include “bar.h”

}

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Which methodology is best to use with C2H???When using the C2H compiler, it is recommended that a user “isolate” the function for acceleration into its own file, so using?the first example is the best approach for accelerating functions with the?C2H compiler.