#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

	// line control, select r/w of divisor latch register
	writeReg(RegisterIndex::LINE_CONTROL,
			 static_cast<uint8_t>(RegisterMask::DIVISOR_LATCH_ACCESS_BIT));

	// config divisor
	uint16_t divisor = static_cast<uint16_t>(baud_rate);
	// write low byte of divisor latch
	writeReg(RegisterIndex::DIVISOR_LOW, divisor & 0xff);
	// write high byte
	writeReg(RegisterIndex::DIVISOR_HIGH, (divisor >> 8) & 0xff);

	// deselect r/w of divisor latch register
	// configure line control
	writeReg(RegisterIndex::LINE_CONTROL, static_cast<uint8_t>(data_bits) |
											  static_cast<uint8_t>(stop_bits) |
											  static_cast<uint8_t>(parity));

	// FIFO: Enable & clear buffers
	writeReg(RegisterIndex::FIFO_CONTROL,
			 static_cast<uint8_t>(RegisterMask::ENABLE_FIFO) |
				 static_cast<uint8_t>(RegisterMask::CLEAR_RECEIVE_FIFO) |
				 static_cast<uint8_t>(RegisterMask::CLEAR_TRANSMIT_FIFO));

	// Modem Control: OUT2 (0000 1000) must be set for interrupt
	writeReg(RegisterIndex::MODEM_CONTROL,
			 static_cast<uint8_t>(RegisterMask::OUT_2));
}

void Serial::writeReg(RegisterIndex reg, uint8_t out) {
	IOPort p(static_cast<uint16_t>(port) + static_cast<uint16_t>(reg));
	p.outb(out);
}

uint8_t Serial::readReg(RegisterIndex reg) {
	IOPort p(static_cast<uint16_t>(port) + static_cast<uint16_t>(reg));
	return p.inb();
}

int Serial::write(uint8_t out) {
	while ((readReg(RegisterIndex::LINE_STATUS) &
			static_cast<uint8_t>(RegisterMask::TRANSMITTER_EMPTY)) == 0) {
	}

	writeReg(RegisterIndex::TRANSMIT_BUFFER, out);
	return out;
}