#include "serial.h"

/*
 * SERIAL_LINE_COMMAND_PORT configuration
 * Bit:     | 7 | 6 | 5 4 3 | 2 | 1 0 |
 * Content: | d | b | prty  | s | dl  |
 * d = enable/disable DLAB
 * b = enable/disable break control
 * prty = # of parity bits to use
 * s = # no of stop bits [0 is 1] and [1 is 1.5 or 2]
 * dl = length of data
 *
 */

void serial_set_baud_rate(const u16 com_port, const u16 divisor) {
	// Activate line - ready to send higher 8 bits of data
	// send the higher 8 bits first
	// send the lower 8 bits next

	serial_control(SERIAL_LINE_COMMAND_PORT(com_port), 
			SERIAL_LINE_ENABLE);

	serial_control(SERIAL_DATA_PORT(com_port), 
			(divisor>>8) & 0x00ff);

	serial_control(SERIAL_DATA_PORT(com_port), 
			divisor & 0x00ff);
}

// Payload described above
void serial_configure_line(const u16 line, const u8 payload) {
	serial_control(SERIAL_LINE_COMMAND_PORT(line), payload);
}

u8 serial_fifo_empty(const u16 com_port) {
	// If the 5th bit is set then we know that the fifo queue is empty
	return serial_read_buffer(SERIAL_LINE_STATUS_PORT(com_port)) & 0x20;
}

u64 serial_write(const s8* buffer, const u64 size) {
	/*
	 * Writes a given buffer to the com1 serial port for debugging in bochs
	 */
	u64 idx = 0;
	serial_set_baud_rate(SERIAL_COM1_BASE, 1); // base baud rate
	while(idx < size) {
		if(serial_fifo_empty(SERIAL_COM1_BASE) == 0x20) {
			serial_control(SERIAL_COM1_BASE, buffer[idx]);
			idx++;
		}
		// otherwise we just wait until the queue is empty
		else {
			continue;
		}
	}
	return idx;
}