serial.c

#include "port-io.h"

#define SERIAL_COM1_BASE                0x3F8
#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_LINE_ENABLE_DLAB         0x80

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));
}

void serial_configure_line(unsigned short com) {
  outb(SERIAL_LINE_COMMAND_PORT(com), 0x03);
}

void serial_configure_buffer(unsigned short com) {
  outb(SERIAL_FIFO_COMMAND_PORT(com), 0xC7);
}

void serial_configure_modem(unsigned short com) {
  outb(SERIAL_MODEM_COMMAND_PORT(com), 0x03);
}

void serial_is_transmit_fifo_empty(unsigned int com) {
  return inb(SERIAL_LINE_STATUS_PORT(com) & 0x20);
}