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Calling C function from ISR

Aykut Birsen

Hi,

I am trying to call a C function from the interrupt subroutine in LPC3250.

When I call the function from a C file, there is no problem. However, when I use a C++ file containing the required function I get an error.

The error says:
Undefined symbol C_Irq_Handler (referred from lpc32x0.o)

How can I call the function from the C++ file?

Thanks for your help.

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  • 0

    This is a standard C/C++ FAQ question.

    You have to do something like:

    extern "C" void myfunction(int);


    to inform the C++ compiler that it should call a C function, and not a C++ function. How else would the C++ compiler be able to know that you are mixing C and C++ code?

    To be type safe, C++ augments the symbol names with data type information, so a call to a C++ function creates a reference to the augmented name - and the linker will then look for this symbol, instead of just the function name. The use of name mangling allows you to have a function my_func(int) and another function my_func(float).

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  • 0

    This is a standard C/C++ FAQ question.

    You have to do something like:

    extern "C" void myfunction(int);


    to inform the C++ compiler that it should call a C function, and not a C++ function. How else would the C++ compiler be able to know that you are mixing C and C++ code?

    To be type safe, C++ augments the symbol names with data type information, so a call to a C++ function creates a reference to the augmented name - and the linker will then look for this symbol, instead of just the function name. The use of name mangling allows you to have a function my_func(int) and another function my_func(float).

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