Introduction to Mixed C and C++ Compilation
IAR C/C++ Compiler supports both C and C++ languages effectively. However, managing a project that combines code in both languages can require careful handling of various factors to ensure smooth integration and compilation. Understanding the nuances of different modules and their interactions is crucial for firmware development.
Project Configuration
Ensure that you have set the file extensions correctly in your project. Conventionally, C files use .c and header files .h, while C++ files use .cpp for implementation and .hpp for headers. This allows the compiler to correctly interpret each file's language context.
Configure your project build options to accommodate both C and C++ compilation. This might involve setting certain flags or paths for C++ libraries within the IDE.
Extern "C" for C++ Compatibility
When using C code in a C++ file, name mangling can cause linkage issues. This is because C++ changes the names of functions, whereas C does not. Use the extern "C" construct to prevent this problem and allow the linker to correctly bind the C and C++ code together:
extern "C" {
#include "my_c_header.h"
}
This tells the C++ compiler to not mangle the names of the C functions or variables.
Compiler Directives and Macros
- Define macros that differentiate between C and C++ during compilation, thereby conditionally compiling code specific to each language.
#ifdef __cplusplus
extern "C" {
#endif
// C Function Declarations
#ifdef __cplusplus
}
#endif
- Use these defines throughout your headers to ensure they can be included in both C and C++ code without causing any issues.
C++ Features and Standard Library Use
Carefully analyze the use of C++ standard library features, especially since embedded environments may have limited support compared to traditional desktop compilers.
Ensure the standard libraries used in your C++ modules are compatible with the IAR embedded C++ standard libraries, typically requiring linking with appropriate libraries offered by IAR.
Linker File and Start-up Code Management
C and C++ modules may have different runtime requirements, such as initialization code. Ensure your project's linker configuration file and start-up assembly code accommodates both runtime environments as needed for initialization and static constructors/destructors.
Use the IAR IDE to configure the linker file—using GUI settings or manually editing script files to handle startup and memory specifics for both languages.
Code Example
Here is an illustrative example for handling mixed C and C++ code within your project:
// C Header: my_c_header.h
#ifndef MY_C_HEADER_H
#define MY_C_HEADER_H
#ifdef __cplusplus
extern "C" {
#endif
void my_c_function();
#ifdef __cplusplus
}
#endif
#endif // MY_C_HEADER_H
// C++ Source File: main.cpp
#include "my_c_header.h"
int main() {
my_c_function();
return 0;
}
Testing and Debugging
Utilize integrated debugging tools provided in IAR for both C and C++ debugging. Take advantage of features such as breakpoints, variable watches, and mixed-language call stack tracking.
Conduct thorough unit testing, verifying both individually and together at the integration level to ensure that C and C++ modules interoperate smoothly without unintended side effects.
By carefully organizing your project setup, using appropriate compiler directives, and testing extensively, managing mixed C and C++ code in IAR's environment can be streamlined and effective.
