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c++arduinoavratmegaavr-gcc

How stack pointer works

I'm trying to make an multithreading kernel for atmega328p micro an for that i need to know how the stack pointer it works.

Solution

  • Most probably, your functions are rightly being inlined, so everything actually gets done straight in setup(), with no function calls involved. If you want to forcefully disable inlining for them (to see the stack pointer change), you can apply the gcc noinline attribute.

    void __attribute__ ((noinline)) func1() {
    ...
}

    If this still doesn't work, it's possible that gcc is applying tail call optimization anyhow. In that case, a simple method to make your functions not prone to this optimization is to print SP both before and after the call.