serial.cc

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#include <stdio.h>
#include <fcntl.h>
#include <sys/time.h>
#include <unistd.h>

#include "serial.h"
#include <string.h>
#include <errno.h>

SerialDevice::~SerialDevice(){
  if (tty_fd_slot != -1) {
    empty_serial (tty_fd_slot);
    close_serial (tty_fd_slot);
  }
}
SerialDevice::SerialDevice(){
  tty_fd_slot = -1;
  strcpy(device_name,"");
}


/******************************************************************************
 ***
 *** Name:       open_serial
 ***
 *** Purpose:    oeffnet ein serielles Device
 ***
 *** Parameters: devicename (z.B. "/dev/ttyS4") und flags (z.B. CS8|B9600 ) 
 ***
 *** Returns:    filedescriptor, bzw. -1 im Fehlerfall
 ***
 ******************************************************************************
 */

int  SerialDevice::open_serial (const char *p_tty_name)
{
   struct termio tty_set;
   int tty_fd = -1;
    
   if ( (tty_fd = open(p_tty_name, O_RDWR |O_NOCTTY)) < 0 )//NONBLOCK
     {
       printf("ERROR: Couldn't open port %s!\n", p_tty_name);
       perror(NULL);
       return (-1);
     }
   
   if (ioctl(tty_fd, TCGETA, &tty_set ) == -1 )
     {
       printf("ERROR: ioctl() failed to read settings!\n");
       perror(NULL);
       return (-1);
     }
   
   tty_set.c_cflag = (B115200 | CS8 | CLOCAL | CREAD);
   tty_set.c_iflag = IXOFF;
   tty_set.c_lflag = 0;
   tty_set.c_oflag = 0;
   tty_set.c_cc[VTIME]    = 20;
   tty_set.c_cc[VMIN]     = 0;

   if (ioctl(tty_fd, TCSETAW, &tty_set ) == -1 ) 
     {
       printf("ERROR: ioctl() failed to set settings!\n");
       perror(NULL);
       return (-1);
     }

   tty_fd_slot = tty_fd;
   strcpy(device_name,p_tty_name);
   return (tty_fd);
}

/******************************************************************************
 ***
 *** Name:       change_baud_serial
 ***
 *** Purpose:    stellt die Geschwindigkeit der seriellen Schnittstelle um
 ***
 *** Parameters: filedescriptor und neue Geschwindigkeit (z.B. B38400)
 ***
 *** Returns:    STATUS_OK, bzw. STATUS_ERROR im Fehlerfall
 ***
 ******************************************************************************
 */

long SerialDevice::change_baud_serial (int tty_fd, speed_t speed)
 {
   struct termio tty_set;

   if (ioctl(tty_fd, TCGETA, &tty_set ) == -1 ) 
     {
       printf("ERROR: ioctl() failed to read settings!\n");
       perror(NULL);
       return (STATUS_ERROR);
     }
   
   tty_set.c_cflag &= ~CBAUD;
   tty_set.c_cflag |= speed;
   
   if (ioctl(tty_fd, TCSETAW, &tty_set ) == -1 ) 
     {
       printf("ERROR: ioctl() failed to set settings!\n");
       perror(NULL);
       return (STATUS_ERROR);
     }

   return (STATUS_OK);
 }

/******************************************************************************
 ***
 *** Name:       write_serial
 ***
 *** Purpose:    Schickt Daten an die serielle Schnittstelle
 ***
 *** Parameters: filedescriptor, Pointer auf Speicher, Zahl der zu versendenden bytes
 ***
 *** Returns:    STATUS_OK, bzw. STATUS_ERROR im Fehlerfall
 ***
 ******************************************************************************
 */

long SerialDevice::write_serial(int tty_fd, unsigned char *p_buffer, long nb_byte)
 {
   int bytes_out;

   if (( bytes_out = write(tty_fd, p_buffer, nb_byte)) < nb_byte)
     {
       printf("ERROR: write() failed!\n");
       perror(NULL);
       return (STATUS_ERROR);
     };

   return (STATUS_OK);
 }

/******************************************************************************
 ***
 *** Name:       read_serial
 ***
 *** Purpose:    Liest Daten von der seriellen Schnittstelle. Liegen gerade
 ***             keine Daten an, wird eine 20tel Sekunde darauf gewartet!
 ***
 *** Parameters: filedescriptor, Pointer auf Speicherbereich, maximale 
 ***             Zahl der zu lesenden bytes
 ***
 *** Returns:    Zahl der gelesenen bytes
 ***
 ******************************************************************************
 */

long SerialDevice::read_serial(int tty_fd, unsigned char *p_buffer, long nb_bytes_max)
 {
   struct timeval tz;
   fd_set fds;
   int tries       = 0;
   int qu_new      = 0;
   int bytes_read  = 0;
   int ready       = STATUS_ERROR;
  
   /* read max nb_bytes_max bytes */

   while (tries < 2 && !ready)
     {
       tz.tv_sec  = 1;
       tz.tv_usec = 0;
       
       FD_ZERO(&fds);
       FD_SET(tty_fd, &fds);
       if (select(FD_SETSIZE, &fds, 0, 0, &tz) > 0)
         {
           qu_new = read(tty_fd, &p_buffer[bytes_read], (nb_bytes_max - bytes_read));
           if (qu_new > 0)
             bytes_read += qu_new;
           else
             tries++;
           ready = (bytes_read == nb_bytes_max);
         }
       else
         tries++;
     }

   return(bytes_read);
 }

/******************************************************************************
 ***
 *** Name:      close_serial
 ***
 *** Purpose:   schliesst das serielle device
 ***
 *** Parameter: filedescriptor
 ***
 ******************************************************************************
 */

void SerialDevice::close_serial (int tty_fd)
 {
   close(tty_fd);
 }

/******************************************************************************
 ***
 *** Name:       wait_for_serial
 ***
 *** Purpose:    Wartet maximal eine vorgegebene Zeit auf das Eintreffen von 
 ***             Daten an der seriellen Schnittstelle
 ***
 *** Parameters: filedescriptor, maximale Wartezeit
 ***
 *** Returns:    STATUS_OK wenn Daten anliegen, bzw. STATUS_ERROR wenn nicht
 ***
 ******************************************************************************
 */

long SerialDevice::wait_for_serial(int tty_fd, long max_time_secs)
 {
   struct timeval tz;
   fd_set fds;

   while (max_time_secs--)
     {
       tz.tv_sec  = 1;
       tz.tv_usec = 0;
       
       FD_ZERO (&fds);
       FD_SET(tty_fd, &fds);
       
       if (select(FD_SETSIZE, &fds, 0, 0, &tz) > 0)
         return (STATUS_OK);
     }  

   return (STATUS_ERROR);
 }


/******************************************************************************
 ***
 *** Name:       empty_serial
 ***
 *** Purpose:    Loescht den Eingangspuffer der seriellen Schnittstelle
 ***
 *** Caveats:    Noch nicht getestet... (see manpage zu termios)
 ***
 *** Parameters: filedescriptor
 ***
 *** Returns:    STATUS_OK, bzw. STATUS_ERROR im Fehlerfall
 ***
 ******************************************************************************
 */

long SerialDevice::empty_serial(int tty_fd)
 {
   if (-1 == tcflush (tty_fd, TCIFLUSH))
     return (STATUS_ERROR);
   else
     return (STATUS_OK);
 }