#include "serial.h"
#include "ioport.h"

Serial::Serial(ComPort port, BaudRate baud_rate, DataBits data_bits,
               StopBits stop_bits, Parity parity)
    : port(port) {
  // initialize FIFO mode, no irqs for sending, irq if first byte was received
  writeReg(INTERRUPT_ENABLE_REGISTER, RECEIVED_DATA_AVAILABLE);

  // line control, select r/w of divisor latch register
  writeReg(LINE_CONTROL_REGISTER, DIVISOR_LATCH_ACCESS_BIT);

  writeReg(DIVISOR_LOW_REGISTER, baud_rate & 0xFF);
  writeReg(DIVISOR_HIGH_REGISTER, (baud_rate>>8) & 0xFF);

  // also turns DLAB off
  uint8_t val = parity;
  val |= stop_bits;
  val |= data_bits;
  writeReg(LINE_CONTROL_REGISTER, val);

  // FIFO: Enable & clear buffers
  writeReg(FIFO_CONTROL_REGISTER,
           ENABLE_FIFO | CLEAR_RECEIVE_FIFO | CLEAR_TRANSMIT_FIFO);

  // Modem Control: OUT2 (0000 1000) must be set for interrupt
  writeReg(MODEM_CONTROL_REGISTER, OUT_2);
}

void Serial::writeReg(RegisterIndex reg, char out) {
  uint16_t addr = port;
  IOPort iop = IOPort(addr += reg);
  iop.outb(out);
}

char Serial::readReg(RegisterIndex reg) {
  uint16_t addr = port;
  IOPort iop = IOPort(addr += reg);
  return iop.inb();
}

int Serial::write(char out) {
  // TODO: Implement
  if(readReg(LINE_STATUS_REGISTER) & TRANSMITTER_EMPTY){
      writeReg(TRANSMIT_BUFFER_REGISTER, out);
      return out;
  }
  return -1;
}