/*
   TestNullModem - Test a null-modem connection (loopback) to make sure
                   traffic is getting through
   Copyright (C) 2004 Frank Sorenson (frank@tuxrocks.com)

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.


   Compiling: gcc TestNullModem.cpp -o TestNullModem
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <termios.h>
#include <fcntl.h>
#include <errno.h>

int SetTerminalSettings(int PortNum)
{
  struct termios TermIO;
  int Result;

  printf("Setting terminal settings\n");

  Result = tcgetattr(PortNum, &TermIO);
  if (Result)
  {
    printf("Error while running tcgetattr\n\r");
  }
  cfsetispeed(&TermIO, B9600);
  cfsetospeed(&TermIO, B9600);
  TermIO.c_cflag |= (CREAD | CLOCAL);
  TermIO.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG | ECHOK | ECHOCTL | ECHOKE);
  TermIO.c_iflag &= ~(ICRNL | IXON);
  TermIO.c_oflag &= ~(OPOST | ONLCR);
  TermIO.c_cflag &= ~PARENB;
  TermIO.c_cflag &= ~CSTOPB;
  TermIO.c_cflag &= ~CSIZE;
  TermIO.c_cflag &= ~CRTSCTS;
  TermIO.c_cflag |= CS8;
   
  Result = tcsetattr(PortNum, TCSANOW, &TermIO);
  if (Result)
  {
    printf("Error while running tcsetattr\n\r");
    return(-1);
  }
  return(0);
}

int OpenDevice(char *DeviceFile)
{
  int PortNum;

  printf("Opening %s\n", DeviceFile);

  PortNum = open(DeviceFile, O_RDWR | O_NOCTTY);
  if (PortNum == -1)
  {
    printf("Could not open device %s\n", DeviceFile);
    exit(-1);
  }
  SetTerminalSettings(PortNum);
  return(PortNum);
}

int DataReady(int PortNum)
{
  fd_set rsel;
  int MaxFDs = 32;
  int Result;
  struct timeval tv;

  tv.tv_sec = 0;
  tv.tv_usec = 0;
  FD_ZERO(&rsel);
  FD_SET(PortNum, &rsel);
  Result = select(MaxFDs, &rsel, NULL, NULL, &tv);
  if (!Result) return(0);
  if (FD_ISSET(PortNum, &rsel) == 0) return(0);
  return(1);
}

int ReceiveChar(int PortNum)
{
  int Result;
  unsigned char Data;

  Result = read(PortNum, &Data, 1);
  if (Result == 1) return(Data);
  return(-1);
}

int TransmitChar(int PortNum, unsigned char Data)
{
  int Result;

  Result = write(PortNum, &Data, 1);
  if (Result == 1) return(1);
  if (errno == ENODEV)
  {
    printf("Lost the connection to the port - ENODEV\n");
    exit(-1);
  }
  printf("Could not send character - %d\n", errno);
  return(-1);
}

int GenTraffic(int PortNum)
{
  unsigned char TempChar;
  unsigned long BytesSent = 0;
  unsigned long BytesReceived = 0;
  double Percentage;

  printf("Starting traffic generator\n");

  while (1)
  {
    TransmitChar(PortNum, '#');
    BytesSent ++;
    if (DataReady(PortNum))
    {
      BytesReceived ++;
      TempChar = ReceiveChar(PortNum);
    }

    Percentage = (BytesReceived * 1.0) / (BytesSent * 1.0) * 100.0;
    printf("%ld sent, %ld received, %ld lost, %.2lf%%\r", BytesSent, BytesReceived, (BytesSent - BytesReceived), Percentage);
    fflush(stdout);
    usleep(1000);
  }
}

int main(int argc, char *argv[])
{
  int PortNum;

  if (argc == 2)
  {
    PortNum = OpenDevice(argv[1]);
  }
  else
  {
    PortNum = OpenDevice("/dev/ttyS0");
  }

  GenTraffic(PortNum);
}