// adrport.c - Serial Port Handler
// Copyright MMI, MMII by Sisusypro Incorporated

// Permission is hereby granted to freely copy, 
// modify, utilize and distribute this example in 
// whatever manner you desire without restriction.

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <string.h>
#include <errno.h>
#include "adrport.h"
static int fd = 0;


main(){
  char buf[100];
  int i;
  OpenAdrPort("6");
  WriteAdrPort("DATETIME?\r\n");
  usleep(1000000);
  ReadAdrPort(buf,100);
  printf("%s",buf);
  for(i=0;buf[i];i++) {
    printf("0x%2.2x\n",buf[i]);
  }
  CloseAdrPort();

}

// opens the serial port
// return code:
//   > 0 = fd for the port
//   -1 = open failed
int OpenAdrPort(char* sPortNumber)
{
    char sPortName[64];
    printf("in OpenAdrPort port#=%s\n", sPortNumber);
    sprintf(sPortName, "/dev/ttyS%s", sPortNumber);
    printf("sPortName=%s\n", sPortName);

    // make sure port is closed
    CloseAdrPort(fd);

    fd = open(sPortName, O_RDWR | O_NOCTTY | O_NONBLOCK);

    if (fd < 0)
    {
        printf("open error %d %s\n", errno, strerror(errno));
    }
    else
    {
        struct termios my_termios;
        printf("fd is %d\n", fd);
        tcgetattr(fd, &my_termios);
        // NOTE: you may want to save the port attributes 
        //       here so that you can restore them later
	/*
        printf("old cflag=%08o\n", my_termios.c_cflag);
        printf("old oflag=%08o\n", my_termios.c_oflag);
        printf("old iflag=%08o\n", my_termios.c_iflag);
        printf("old lflag=%08o\n", my_termios.c_lflag);
        printf("old line=%03o\n", my_termios.c_line);
	*/
        tcflush(fd, TCIFLUSH);
        tcflush(fd, TCOFLUSH);
        
        my_termios.c_cflag = CS7 | CREAD | CLOCAL | HUPCL| PARENB | PARODD;
	//	my_termios.c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
	my_termios.c_iflag &= ~ICRNL;
	my_termios.c_lflag = 0;
        
        cfsetospeed(&my_termios, B9600);
        tcsetattr(fd, TCSANOW, &my_termios);
	/* 
        printf("new cflag=%08o\n", my_termios.c_cflag);
        printf("new oflag=%08o\n", my_termios.c_oflag);
        printf("new iflag=%08o\n", my_termios.c_iflag);
        printf("new lflag=%08o\n", my_termios.c_lflag);
        printf("new line=%03o\n", my_termios.c_line);
	*/
    } // end if
    return fd;
} // end OpenAdrPort

// writes zero terminated string to the serial port
// return code:
//   >= 0 = number of characters written
//   -1 = write failed
int WriteAdrPort(char* psOutput)
{
    int iOut;
    if (fd < 1)
    {
        printf(" port is not open\n");
        return -1;
    } // end if
    iOut = write(fd, psOutput, strlen(psOutput));
    if (iOut < 0)
    {
        printf("write error %d %s\n", errno, strerror(errno));
    }
    else
    {
    	printf("wrote %d chars: %s\n", iOut, psOutput);
    } // end if
    return iOut;
} // end WriteAdrPort

// read string from the serial port
// return code:
//   >= 0 = number of characters read
//   -1 = read failed
int ReadAdrPort(char* psResponse, int iMax)
{
    int iIn;
    int i;
    printf("in ReadAdrPort iMax=%d\n", iMax);
    if (fd < 1)
    {
        printf(" port is not open\n");
        return -1;
    } // end if
    strncpy (psResponse, "N/A", iMax<4?iMax:4);
    iIn = read(fd, psResponse, iMax-1);
    if (iIn < 0)
    {
    	if (errno == EAGAIN)
    	{
		return 0; // assume that command generated no response
	}
	else
	{
		printf("read error %d %s\n", errno, strerror(errno));
	} // end if
    }
    else
    {
    	psResponse[iIn<iMax?iIn:iMax] = '\0';
	    printf("read %d chars: %s\n", iIn, psResponse);
    } // end if
    for(i=0;psResponse[i];i++) {
      psResponse[i] &= 0x7f;
    }
    return iIn;
} // end ReadAdrPort

// closes the serial port
void CloseAdrPort()
{
	// you may want to restore the saved port attributes
    if (fd > 0)
    {
        close(fd);
    } // end if
} // end CloseAdrPort