// 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>


static int fd = 0;

// closes the serial port
void CloseAdrPort() {	
    if (fd > 0) {
        close(fd);
    } 
} // end CloseAdrPort

// opens the serial port
// return code:
//   > 0 = fd for the port
//   -1 = open failed
int OpenAdrPort()
{
    // make sure port is closed
    CloseAdrPort();

	/*  O_RDWR = read/write, 
        O_NOCTTY = If pathname refers to a terminal device -- see tty(4) -- it will 
		not become the process's controlling terminal even if the process does not have one
		O_NDELAY = The file is opened in non-blocking mode. Neither the open nor any subsequent operations 
		on the file descriptor which is returned will cause the calling process to wait. */
    fd = open("/dev/ttyS0", O_RDWR);

    if (fd < 0) {
        printf("Error opening /dev/ttyS0: %d %s\n", errno, strerror(errno));
    } else {
        struct termios my_termios;
        
		/* gets the parameters associated with the object
           referred by fd and stores them in  the  termios  structure */
        tcgetattr(fd, &my_termios);
       
	   /* flushes data received but not read */
        tcflush(fd, TCIFLUSH);
        
		/* 2400bps, 8 bit data, enable receive, ignore modem control lines
	
		lower modem control after last process leaves the device
	*/
        my_termios.c_cflag = CREAD | CLOCAL | CS8; // | PARENB | PARODD;
        
		/* sets transmission speed to 2400bps */
        cfsetospeed(&my_termios, B2400);
	cfsetospeed(&my_termios, B2400);

		/* sets the parameters associated with the terminal.
		TCSANOW = the change occurs immediately. */
        tcsetattr(fd, TCSANOW, &my_termios);
	} 
    
	return fd;

} // end OpenAdrPort

// writes zero terminated string to the serial port
// return code:
//   >= 0 = number of characters written
//   -1 = write failed
int WriteAdrPort(unsigned char* output,int length) {
	int k;
    for (k = 0; k < length; k++) {
	printf("Valor: %d\n", ((int)output[k]));
	}
     int iOut;
    
	if (fd < 1) {
        printf("Write error: port is not open.\n");
        return -1;
    } 
	
	/* the number of bytes written are returned */
    iOut = write(fd, output, length);

    if (iOut < 0) {
        printf("Write error: %d %s\n", errno, strerror(errno));
    } else {
    	printf("Wrote %d chars.\n", iOut);
    } 

    return iOut;

} // end WriteAdrPort

// read string from the serial port
// return code:
//   >= 0 = number of characters read
//   -1 = read failed
int ReadAdrPort(unsigned char* psResponse, int& length, int iMax)
{
    int iIn;
    
    if (fd < 1) {
        printf("Read error: port is not open.\n");
        return -1;
    } 
    //sleep(1);
    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));
		} 
    } else {
    	printf("Read %d bytes.\n", iIn);
    } 

	length = iIn;

    return iIn;
} // end ReadAdrPort