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MSP430FR6047: __bic_SR_register_on_exit assembly code needed

tunguskar
Intellectual 380 points
Part Number: MSP430FR6047

HI,

I have to abstract the call to 

__bic_SR_register_on_exit 
My Problem: I call this routine from an interrupt routine but in a subroutine. The compiler does not recognize this unfortunately, so I get a compiler error. 
Is it possible to get the assembly code for this routine?

Kind regards

  • 0
    Intellectual 380 points

    Maybe a bit code to see what I want to achieve:

    template <typename Derived>
class ITest
{

  public:
  static constexpr inline void wakeup()
  {
    Derived::wakeupImpl();
  }
};

class Test : public ITest<Test>
{
  protected:

  friend class ITest<Test>;
  static constexpr inline void wakeupImpl()
  {
    __bic_SR_register_on_exit(LPM3_bits);
  }

};

void __attribute__((interrupt(USCI_A0_VECTOR))) USCI_A0_ISR(void)
{
  WakeState wakeState;
  MyUart::intByteReceived(wakeState);

  if(wakeState == WakeState::Wakeup)
  {
    Test::wakeup();
  }
}

    leads to this error: 

    error: MSP430 builtin functions only work inside interrupt handlers
    [build]    84 |     __bic_SR_register_on_exit(LPM3_bits);
  • 0 in reply to tunguskar
    Guru 19835 points

    This must be used within the ISR because the compiler must know exactly where on the stack the SR register was saved. It knows that in the ISR but not within a function called from the ISR.

    Given that it says "on_exit" I would assume that this would usually, but not always, be deferred until just before the rti instruction.

    The instruction used is "bic #LMP3_bits,offset(SP)". You could of course use an asm() statement to insert that using an offset you determined to work. Today. It could of course break tomorrow when you update the compiler. Or change optimization level.

  • 0 in reply to David Schultz
    Intellectual 380 points 

    static __attribute__((always_inline)) inline void wakeUp()

    Thanks for the answer. My solution, to keep the abstraction, is now to force inlining. This works.

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