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From: scs@adam.mit.edu (Steve Summit)
Newsgroups: comp.unix.programmer
Subject: Re: Losing pending input in entering RAW or CBREAK
Message-ID: <1991May7.012922.2647@athena.mit.edu>
Date: 7 May 91 01:29:22 GMT
References: <5027@lib.tmc.edu> <243@bria.UUCP>
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In article <243@bria.UUCP> uunet!bria!mike writes:
>In an article, dfenyes@thesis1.med.uth.tmc.edu (David Fenyes) writes:
>|When I switch from cooked to CBREAK, any pending input appears
>|to be discarded.  How can this be avoided or worked around?
>|
>|I'm using Coherent.  Is this an anomaly, or standard tty behavior?
>
>An excerpt from The Holiest of Tomes:
>
>	TCSETA		set the parameters associated with the terminal
>			from the structure passed as `arg'.  The change
>			is immediate
>
>	TCSETAF		wait for the output to drain and flush the input
>			queue before setting the new parameters
>
>It would seem that the ioctl() that is setting the terminal characteristics
>is using TCSETAF which is forcing the flush on the input queue.  If
>your cbreak is homegrown, then try using TCSETA instead.

I'm not familiar with Coherent, either, and Michael is probably
correct in assuming that it is termio and/or termios based, but
in case it derives from V7 and/or BSD, the equivalent ioctl's are

	TIOCSETP	set tty parameters (and flush pending input)
	TIOCSETN	set tty parameters (no flush of pending input)

                                            Steve Summit
                                            scs@adam.mit.edu