// C-like pseudo code for interrupt handler
//
// Some of the things needed to write an interrupt handler cannot be
// expressed in high-level languages (e.g., reading the cause
// register, saving the assembler temporary, returning from an
// exception).  This is why this kind of code (usually part of the
// operating system) has to be written in assembly).

void
interrupt_handler() {
  // save assembler temporary (so we don't accidentally overwrite it)
  // save $a0, $a1 registers (so we have some registers to work with)

  int cause_register = get_cause_register();  // read a coprocessor register
  if (((cause_register >> 2) & 0xf) != 0) {
    // handle exception
    return;
  }

  // otherwise it was an interrupt

  while (1) { 
    cause_register = get_cause_register();  // it could have changed
    if (cause_register == 0) {
      break;  // no more unhandled interrupts
    }

    if (cause_register & COLLISION_INTERRUPT_MASK) {  // bonk interrupt (we ran into a wall)
      set_relative_angle(70);       // write a couple I/O registers
      set_velocity(10);             // write a different I/O register
      acknowledge_bonk_interrupt(); 
      continue;
    } 

    if (cause_register & OTHER_INTERRUPT_MASK) {  // handle other interrupt
      // ...
    }
  }

  // restore $a0, $a1
  // restore assembler temporary
  return_from_exception();
}