9 years, 3 months ago.  This question has been closed. Reason: Too broad - no single answer

Thread or RtosTimer as member variable

Hey guys. Sorry if this has come up before, but I'm looking for the best way for a class to use one or more Threads or RtosTimers internally. The problem is that RTX only accepts regular C function pointers, not C++ method pointers. Any ideas?

UPDATE

I may have figured out a solution, but I need somebody smarter than me to tell me if it makes sense. I added a static helper method to my class that matches the expected Thread function signature. Then, from inside the class, I create a Thread object using this helper method as the thread function, passing in the this pointer as the thread argument. The helper method casts the const void* argument back to an instance pointer, and calls the thread method. The thread method then executes a while loop, same as normal, except now it has access to the internal member variables. Make sense? I've attached some code:

#ifndef TEST_CLASS_H
#define TEST_CLASS_H

#include "mbed.h"
#include "rtos.h"

/** TestClass class.
 *  Used for demonstrating stuff.
 */
class TestClass
{
public:
    /** Create a TestClass object with the specified specifics
     *
     * @param led The LED pin.
     * @param flashRate The rate to flash the LED at in Hz.
     */
    TestClass(PinName led, float flashRate);

    /** Start flashing the LED using a Thread
     */
    void start();

private:
    //Member variables
    DigitalOut m_Led;
    float m_FlashRate;
    Thread* m_Thread;

    //Internal methods
    static void threadHelper(const void* arg);
    void threadMethod();
};

#endif

#include "TestClass.h"

TestClass::TestClass(PinName led, float flashRate) : m_Led(led, 0), m_FlashRate(flashRate)
{
    //NOTE: The RTOS hasn't started yet, so we can't create the internal thread here
}

void TestClass::start()
{
    //Create the internal thread using the helper function
    m_Thread = new Thread(TestClass::threadHelper, this);
}

void TestClass::threadHelper(const void* arg)
{
    //Cast the argument to a TestClass instance pointer
    TestClass* instancePtr = static_cast<TestClass*>(const_cast<void*>(arg));

    //Call the thread method for the TestClass instance
    instancePtr->threadMethod();
}

void TestClass::threadMethod()
{
    while (1) {
        //Toggle the LED
        m_Led = !m_Led;

        //Wait for a period of time
        Thread::wait((1.0 / m_FlashRate) * 1000);
    }
}

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