C++@embedded

Selected C++ Features

We don't enable Embedded C++ (EC++) since it disables most features of C++. Instead, we only disable some C++ features which will cause performance penalty, especially the "Exceptions" and "RTTI" features which are already disabled by default.

C++ Language Feature	Performance Penalty	EC++ Subset	Our Choice
Classes	No	Yes	Yes
Overloading	No	Yes	Yes
Operator Overloading	No	Yes	Yes
Inheritance (derived classes)	No	Yes	Yes
Wide Character Support	No	Yes	UTF-8
Multiple Inheritance	No	No	Yes
Templates	No	No	Yes
Namespaces	No	No	Yes
Polymorphism (virtual functions)	Only when used	Yes	Yes
Virtual Base Classes	Only when used	No	Yes
Dynamic Casts	Only when used	No	Yes
Run-time Type Identification (RTTI)	Yes, even not used	No	No
Exceptions	Severe, even not used	No	No

TI C++ compilers supply a full implementation of the C++ library, including the STL. The C++ additions to the library are obtained from Dinkumware, a world class supplier of C++ libraries.

Task Encapsulation

It will be more convenient if RTOS can provide encapsulated C++ classes for task run-loop. PicOS has built-in a Task class to simplify the usage.

class MyTask: public pos::Task
{
private:
    int x;
public:
    MyTask();
    ~ MyTask();
    run();
};

where pos is the namespace of PicOS. run() is the run-loop which is declared as a virtual function to be further defined by the derived class.

void MyTask::run()
{
    while(1){
        msg_t msg;
        if(msgPend(&msg, 1000)){
            switch(msg.MsgID){
                case MSG_KEY_DOWN:
                    ...
                    break;
                case ...
            }
        }
    }
}