#include <avr/interrupt.h>

#include "pins_arduino_mega.h"

#include "GPIO.h"
using namespace AP_HAL_AVR;

ArduinoGPIO* ArduinoDigitalSource::parent;

// Get the bit location within the hardware port of the given virtual pin.
// This comes from the pins_*.c file for the active board configuration.

#define analogInPinToBit(P) (P)


// Get the bit location within the hardware port of the given virtual pin.
// This comes from the pins_*.c file for the active board configuration.
// 
// These perform slightly better as macros compared to inline functions
//
#define digitalPinToPort(P) ( pgm_read_byte( digital_pin_to_port_PGM + (P) ) )
#define digitalPinToBitMask(P) ( pgm_read_byte( digital_pin_to_bit_mask_PGM + (P) ) )
#define digitalPinToTimer(P) ( pgm_read_byte( digital_pin_to_timer_PGM + (P) ) )
#define analogInPinToBit(P) (P)
#define portOutputRegister(P) ( (volatile uint8_t *)( pgm_read_word( port_to_output_PGM + (P))) )
#define portInputRegister(P) ( (volatile uint8_t *)( pgm_read_word( port_to_input_PGM + (P))) )
#define portModeRegister(P) ( (volatile uint8_t *)( pgm_read_word( port_to_mode_PGM + (P))) )


void ArduinoGPIO::pinMode(uint8_t pin, uint8_t mode) {
    uint8_t bit = digitalPinToBitMask(pin);
    uint8_t port = digitalPinToPort(pin);
    volatile uint8_t *reg;

    if (port == NOT_A_PIN) return;

    // JWS: can I let the optimizer do this?
    reg = portModeRegister(port);

    if (mode == GPIO_INPUT) {
        uint8_t oldSREG = SREG;
                cli();
        *reg &= ~bit;
        SREG = oldSREG;
    } else {
        uint8_t oldSREG = SREG;
                cli();
        *reg |= bit;
        SREG = oldSREG;
    }
}

uint8_t ArduinoGPIO::read(uint8_t pin) {
    uint8_t bit = digitalPinToBitMask(pin);
    uint8_t port = digitalPinToPort(pin);

    if (port == NOT_A_PIN) return 0;

    if (*portInputRegister(port) & bit) return 1;
    return 0;
}

void ArduinoGPIO::write(uint8_t pin, uint8_t value) {
    uint8_t bit = digitalPinToBitMask(pin);
    uint8_t port = digitalPinToPort(pin);
    volatile uint8_t *out;

    if (port == NOT_A_PIN) return;

    out = portOutputRegister(port);

    uint8_t oldSREG = SREG;
    cli();

    if (value == 0) {
        *out &= ~bit;
    } else {
        *out |= bit;
    }

    SREG = oldSREG;
}

AP_HAL::DigitalSource* ArduinoGPIO::channel(int n) {
  if (ArduinoDigitalSource::parent == NULL) {
    ArduinoDigitalSource::parent = this;
  }
  return new ArduinoDigitalSource(n);
}

void ArduinoDigitalSource::mode(uint8_t output) {
  parent->pinMode(_pin, output);
}

uint8_t ArduinoDigitalSource::read() {
  return parent->read(_pin);
}

void ArduinoDigitalSource::write(uint8_t value) {
  parent->write(_pin, value);
}