Legacy-Sync/serial.c

#include "headers/common.h"
#include "headers/screen.h" // for conversion functions(maybye put in seperate header)
#include <stdarg.h>

#define SERIAL_DATA_PORT(base)	(base)
#define SERIAL_FIFO_COMMAND_PORT(base)  (base + 2)
#define SERIAL_LINE_COMMAND_PORT(base)  (base + 3)
#define SERIAL_MODEM_COMMAND_PORT(base) (base + 4)
#define SERIAL_LINE_STATUS_PORT(base)   (base + 5)
#define SERIAL_COM1_BASE 0x3F8 // com1 base port

// SERIAL_LINE_ENABLE_DLAB:
// tells the serial port to expect high byte first
// then the low order byte follows

#define SERIAL_LINE_ENABLE_DLAB	0x80


/** serial_configure_baud_rate:
*  Sets the speed of the data being sent. The default speed of a serial
*  port is 115200 bits/s. The argument is a divisor of that number, hence
*  the resulting speed becomes (115200 / divisor) bits/s.
*
*  @param com      The COM port to configure
*  @param divisor  The divisor
*/

void serial_configure_baud_rate(unsigned short com, unsigned short divisor)
{
	outb(SERIAL_LINE_COMMAND_PORT(com),
		SERIAL_LINE_ENABLE_DLAB);
	outb(SERIAL_DATA_PORT(com),
		(divisor >> 8) & 0x00ff);
	outb(SERIAL_DATA_PORT(com),
		divisor & 0x00ff);
}

// configures line of a serial port
void serial_configure_line(unsigned short com)
{
	 /* Bit:     | 7 | 6 | 5 4 3 | 2 | 1 0 |
      * Content: | d | b | prty  | s | dl  |
	  * Value:   | 0 | 0 | 0 0 0 | 0 | 1 1 | = 0x03
      */
	outb(SERIAL_LINE_COMMAND_PORT(com), 0x03);

}



// Bit:     | 7 6 | 5  | 4 | 3   | 2   | 1   | 0 |
// Content: | lvl | bs | r | dma | clt | clr | e |
// 0xc7
/*
*Enables FIFO
*Clear both receiver and transmission FIFO queues
*Use 14 bytes as size of queue
*/
void serial_configure_buffers(unsigned short com)
{
	outb(SERIAL_FIFO_COMMAND_PORT(com), 0xc7);
		
}

// configure the modem of our serial port
// Bit:     | 7 | 6 | 5  | 4  | 3   | 2   | 1   | 0   |
// Content: | r | r | af | lb | ao2 | ao1 | rts | dtr |
void serial_configure_modem(unsigned short com)
{
	outb(SERIAL_MODEM_COMMAND_PORT(com), 0x3);

}

/** serial_is_transmit_fifo_empty:
*  Checks whether the transmit FIFO queue is empty or not for the given COM
*  port.
*
*  @param  com The COM port
*  @return 0 if the transmit FIFO queue is not empty
*          1 if the transmit FIFO queue is empty
*/
int serial_is_trasmit_fifo_empty(unsigned short com)
{
	return inb(SERIAL_LINE_STATUS_PORT(com)) & 0x20;
}

void serial_write(unsigned short com, char data)
{

	while(serial_is_trasmit_fifo_empty(com) == 0); // wait till write finished
	outb(com, data);
}


void serial_print(char *string)
{
	int j = 0;
	while(string[j] != 0)
	{
		serial_write(0x3f8, string[j]);
		j++;
	}
}

void serial_printf(const char *format, ...) // printf style func for serial port
{
	int j = 0;
	int num; // number to hold our stuff :)
	char string2[10] = {0}; // string for printing ints :)
	/* list stuff :) */
	va_list ap;
	va_start(ap, format);


	while(format[j] != 0)
	{
		if(format[j] == '%') // if a format specifier
		{
			if(format[j+1] == 'd')
			{
				num = va_arg(ap, int);
				itoa(num, string2);
				serial_print(string2);
				zerostring(string2);
				j += 2;
			}
			
			else if(format[j+1] == 'x')
			{
				num = va_arg(ap, int);
				tohex(num, string2);
				serial_print(string2);
				zerostring(string2);
				j += 2;
			}
			
			else if(format[j+1] == 's')
			{
				serial_print(va_arg(ap, char* ));
				j += 2;
			}

			else // unknown format string
			{
				serial_print("[ERROR]attempted to parse unknown format string\n");
				return; // prevent undefined behaviour
			}
		}

		else  // is a regular character
		{
			serial_write(0x3f8,format[j]);
			j++;
		}
	}
	va_end(ap); // clean up variable length list
}

// init our serial com1 port for debuggin purpoes(rest are general use functions for other ports)
#define PORT 0x3f8   /* COM1 */

void init_serial() 
{
   outb(PORT + 1, 0x00);    // Disable all interrupts
   outb(PORT + 3, 0x80);    // Enable DLAB (set baud rate divisor)
   outb(PORT + 0, 0x03);    // Set divisor to 3 (lo byte) 38400 baud
   outb(PORT + 1, 0x00);    //                  (hi byte)
   outb(PORT + 3, 0x03);    // 8 bits, no parity, one stop bit
   outb(PORT + 2, 0xC7);    // Enable FIFO, clear them, with 14-byte threshold
   outb(PORT + 4, 0x0B);    // IRQs enabled, RTS/DSR set
}