/***                 LISTING 2                ***/
/***                                          ***/
/***                   set.c                  ***/
/*** **************************************** ***/
/***          SET SERIAL PARAMETERS           ***/
/*** **************************************** ***/
#include "serial.h"

int portbase;

int SetSerial (int ComPort,long Baud,int Parity,
			   int DataBits,int StopBits)
{
  if (SetPort(ComPort))
     {
      return (-1);
     }

  if (SetBaud(Baud))
     {
      return (-1);
     }

  if (SetOthers(Parity,DataBits,StopBits))
     {
      return (-1);
     }

return (0);
}

/*** **************************************** ***/
/***  SET THE PORT VALUE TO CORRECT COM PORT  ***/
/*** **************************************** ***/

int SetPort (int ComPort)
{
  switch (ComPort)
    {
	case COM1:   portbase = COM1BASE;
		     break;

	case COM2:   portbase = COM2BASE;
		     break;

	case COM3:   portbase = COM3BASE;
		     break;

	case COM4:   portbase = COM4BASE;
		     break;

	default:     return (-1);
    }
  return (0);
}

/*** **************************************** ***/
/***  SET THE BAUD RATE - DLAB MUST BE SET ON.***/
/*** **************************************** ***/
int SetBaud (long Baud)
{
  char Current_Value;
  int  divisor;

  if ((Baud <= 0) || (Baud > 115200L))
    {
     return (-1);
    }

  else
    {
     divisor = (int)(115200L/Baud);
    }

 /*** READ CURRENT VALUES IN LINE CONTROL REG ***/

   Current_Value = inp(portbase + LCR);

 /*** OR CURRENT VALUE WITH 0x80 TO SET DLAB  ***/

   outp(portbase + LCR,(Current_Value | DLAB));

 /***    OUTPUT BAUD DIVISOR TO LOW BYTE      ***/

   outp(portbase + DLL,(divisor & 0x00FF));

 /***   OUTPUT BAUD DIVISOR TO HIGH BYTE      ***/

   outp(portbase + DLH,((divisor >> 8) & 0x00FF));

 /*** TURN DLAB OFF BY SENDING CURRENT VALUE  ***/

   outp(portbase + LCR,Current_Value);

return (0);
}

/*** **************************************** ***/
/***   SET PARITY, DATA BITS, AND STOPBITS    ***/
/*** **************************************** ***/
int SetOthers (int Parity,int DataBits,int StopBits)
{
  int setting;

  if ((DataBits < 5) || (DataBits > 8))
     {
      return (-1);
     }

  if ((StopBits != 1 && StopBits != 2))
     {
      return (-1);
     }

  if ((Parity != NO_PARITY) && (Parity != ODD_PARITY)
			&& (Parity != EVEN_PARITY))
     {
      return (-1);
     }

  setting = DataBits - 5;
  setting |= ((StopBits == 1) ? 0x00 : 0x04);
  setting |= Parity;

  outp(portbase + LCR,setting);

  return (0);
}