Function ub_dist_rjmp

avr/libraries/Flash/src/urboot.cpp:224–230

Compute from rjmp opcode the relative distance, in bytes, of rjmp destination to rjmp address

// Compute from rjmp opcode the relative distance, in bytes, of rjmp destination to rjmp address
int16_t ub_dist_rjmp(uint16_t rjmp) {
  int16_t dist;

  dist = (int16_t)(rjmp<<4) >> 3; // Sign-extend 12-bit word distance and multiply by 2

  return ub_rjmpdistwrap(dist+2); // Wraps around in flashes smaller than 8k
}

// rjmp opcode from byte distance (rjmp address minus destination address); 0xcfff is an endless loop, 0xc000 is a nop
uint16_t ub_rjmp_opcode(int16_t dist) {