shawn@jdyx.UUCP (Shawn Hayes) (03/26/90)
I'm trying to set up a program to read and write characters to a tty
port. What I would like to have happen is I read a character from the port
and if it's a numeric character I echo it back, and if it is anything else
I ignore it. Currently I can type in alphabetic characters and they are ignored
, but as soon as I echo a numeric character back to the terminal the port
echoes every character.
I've set up the port with a stty -echo -echoe -echok raw
but something must still be wrong in the setup. Is there a way to configure
a tty port to never echo characters, so that only the output from my program
shows up on the port?
Shawn Hayespenneyj@servio.UUCP (D. Jason Penney) (03/27/90)
[100 lashes with a wet noodle for anyone who doesn't post enough return address that one can follow up with e-mail!] In article <1990Mar25.170947.2415@jdyx.UUCP> shawn@jdyx.UUCP (Shawn Hayes) writes: > > I'm trying to set up a program to read and write characters to a tty >port. What I would like to have happen is I read a character from the port >and if it's a numeric character I echo it back, and if it is anything else >I ignore it. Currently I can type in alphabetic characters and they are ignored >, but as soon as I echo a numeric character back to the terminal the port >echoes every character. > > I've set up the port with a stty -echo -echoe -echok raw >but something must still be wrong in the setup. Is there a way to configure >a tty port to never echo characters, so that only the output from my program >shows up on the port? > > Shawn Hayes You don't say what brand of pUnyx you're running, but I suppose from the Newsgroups line that it's some form of AIX. I strongly recommend setting the terminal into RAW mode directly from within your program (i.e., c_lflag &= ~(HUPCL | ICANON | ISIG | ECHO), c_cc[VMIN] = 1, c_cc[VTIME] = 0). Note: the BSD incantation is somewhat different from this... I suspect from your description that you're using stdio to do the echoing. It could possibly be the case that stdio clears these flags. Workaround: use sprintf() to build the strings and then use write(2) to output the characters to the screen. This works like a champ for me in all pUnyx variants. -- D. Jason Penney Ph: (503) 629-8383 Beaverton, OR 97006 uucp: ...uunet!servio!penneyj (penneyj@slc.com) "Talking about music is like dancing about architecture." -- Steve Martin
guy@auspex.auspex.com (Guy Harris) (03/28/90)
>I strongly recommend setting the terminal into RAW mode directly >from within your program (i.e., > >c_lflag &= ~(HUPCL | ICANON | ISIG | ECHO), >c_cc[VMIN] = 1, c_cc[VTIME] = 0). Well: 1) HUPCL has nothing to do with "raw mode"; 2) you may or may not want to turn ISIG off. Turning it off means your interrupt character (^C, <DEL>, whatever) has no effect; leaving it on means that it still generates the appropriate signal. If you *do* want to be able to interrupt things with ^C or <DEL> or whatever, leave it on, but remember to *catch* the SIGINT signal and restore the tty modes back to their original values before exiting. >Note: the BSD incantation is somewhat different from this... BSD RAW mode turns off the signal characters; BSD CBREAK mode doesn't, just as turning ICANON off doesn't. >I suspect from your description that you're using stdio to do the >echoing. It could possibly be the case that stdio clears these flags. The only terminal "ioctl" function every standard I/O implementation I know of does is the one to read the current settings, and it only does that to see if a file descriptor refers to a terminal. None of them change the settings; it's conceivable that some broken implementation out there does, but it's unlikely.