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From: bill@twwells.uucp (T. William Wells)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Re: keyscan wanted
Message-ID: <1016@twwells.uucp>
Date: 5 Jun 89 23:59:54 GMT
References: <1006@twwells.uucp> <607@wn2.sci.kun.nl>
Reply-To: bill@twwells.UUCP (T. William Wells)
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In article <607@wn2.sci.kun.nl> medfys@wn2.sci.kun.nl (Victor Langeveld/Tjeerd Dijkstra) writes:
: In article <1006@twwells.uucp>, bill@twwells.uucp (T. William Wells)
: writes:
: > In article <475@wn2.sci.kun.nl> medfys@wn2.sci.kun.nl (Victor Langeveld/Tjeerd Dijkstra) writes:
: > : I am searching for a (small?) routine that informs me about a
: > : possible pressed key. This routine should *not* wait for input,
: > : but return immediately, wether succesfull or not.
: > : Suggestions?
: >
: > Yes. Tell us what hardware and OS you are talking about.
: >
: > For example, this should be doable on my system, a '386 running
: > Microport's Unix, by telling the driver to return scan codes and
: > doing nonblocking reads. It's all in the relevant sections of the
: > manual, under keyboard(7), open(2), and fcntl(2), and maybe a few
: > other places I can't think of off hand.
: >
: > But on your system, who knows? We certainly don't, since we don't
: > know the system.
: >
: > ---
: > Bill                            { uunet | novavax } !twwells!bill
:
: There is no need to know what hardware this should be working on.
: Mr Charles Thayer (Thanks again, Charles!) gave me a perfect solution:
:
: int key_pressed()
: {
:       int mask=1;
:       struct timeval wait;
:
:       wait.tv_sec=0;
:       wait.tv_usec=0;
:       return (select(1,&mask,0,0,&wait));
: }
:
: This can be used as e.g. if(!key_pressed) { do stuff} else { key
: handling}. Works fine! (As is should (?) on any unix machine)

Leaving aside the possible interpretational problem (the solution I
suggested *really* permits checking for key pressed, and key
released, too), you're talking BSD. Your code won't work on my sysV
3.0 and on many others.

---
Bill                            { uunet | novavax } !twwells!bill