termios raw question

Fernando RUIZ CASAS correo at fernando-ruiz.com
Fri Feb 17 08:04:55 UTC 2006

HI jennifer,


You have availiable a raw stream.

   setvbuf(stdin,NULL,_IONBF,0); /* Not buffered*/
   /* make a raw terminal,Linux MANuals */
   if (tcgetattr (fileno(stdin), &term)>=0) {
    term.c_iflag &= 
    term.c_oflag &= ~OPOST;
    term.c_oflag |= (OPOST|ONLCR); /* But with cr+nl on 
output */
    term.c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
    term.c_cflag  = CLOCAL | CREAD |(shell_env->tcflag);
    term.c_cc[VMIN]  = 1;
    term.c_cc[VTIME] = 0;
    if (tcsetattr (fileno(stdin), TCSADRAIN, &term) < 0) {
      fprintf(stderr,"shell:cannot set terminal 
A lot of RTEMS people use it in telnetd and shell serial 
console without problems.

Maybe in the output better set to no CR+LF.

See you.

On Tue, 14 Feb 2006 18:03:13 -0600 (CST)
  "Jennifer Averett" <jennifer.averett at oarcorp.com> wrote:
> I'm trying to use termios for reading/writing a raw data 
> I am using tcgetattr to get the attributes then setting:
>  termios_attr.c_iflag &= ~(IXON|IXANY|IXOFF);
>  termios_attr.c_oflag &= ~OPOST;
>  termios_attr.c_lflag &= 
>  termios_attr.c_cflag = CREAD;
>  termios_attr.c_cflag &= ~(CSIZE|PARENB);
>  Setting Baud rate in c_cflag based upon a table value
>  Setting bits per charachter in c_cflag based upon a 
>table value
>  Setting parity in c_cflag based upon a table value
>  Setting number in c_cflag of stop bits based upon a 
>table value
>  Settiing flow control in c_iflag based upon a table 
> Then I use tcsetattr to set the attribute.  I found a 
>problem where 0xd
> was being changed to a 0xa with this code and replaced 
>the first c_iflag
> setting with:
>  termios_attr.c_iflag &= ~(IXON|IXANY|IXOFF|ICRNL);
> However this causes a queue overflow when reading the 
>device.  Does anyone
> know if clearing ICRNL, would have the effect of 
>hoarding input characters
> and if so how to keep this from happening?  Any other 
>suggestions would be
> appreciated.
> Jennifer

More information about the users mailing list