gistfile1.txt

Arduino.h:
#define digitalPinToPort(P) digitalPinToPortFunction(pin);
static inline uint8_t digitalPinToPortFunction(uint8_t pin) __attribute__((always_inline));
static inline uint8_t digitalPinToPortFunction(uint8_t pin) {
#if !defined(ARDUINO_MAIN)
  if __builtin_constant_p(pin)
    return digital_pin_to_port[P];
  else
#endif
    return pgm_read_byte( digital_pin_to_port_PGM + pin );
}

#ifdef ARDUINO_MAIN
#define DIGITAL_PIN_TO_PORT_TABLE const uint8_t PROGMEM digital_pin_to_port_PGM[]
#else
#define DIGITAL_PIN_TO_PORT_TABLE static const uint8_t PROGMEM digital_pin_to_port[]
#endif

pins_arduino.h:

DIGITAL_PIN_TO_PORT_TABLE = {
	PD, /* 0 */
	PD,
	etc.
}