From:	jmarin AT pyy DOT jmp DOT fi (Jukka Marin)
Newsgroups:	comp.os.msdos.djgpp
Subject:	usleep() and 95dos problems
Date:	24 Jul 1997 07:07:03 GMT
Organization:	Muikku Internet Server (JMP-Electronics)
Lines:	38
Message-ID:	<slrn5tdvon.1hb.jmarin@pyy.jmp.fi>
NNTP-Posting-Host:	pyy.jmp.fi
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

I'm new to djgpp (and dos programming in general :-)  I'm trying to write
a packet protocol which requires small, but accurate time delays.  I was
happy to find the usleep() call - and unhappy to find out it doesn't
work properly.  Not on my hardware, at least.

If I have a loop like this:

    while(1) {
        printf("huu\n");
        for (i = 0; i < 1000; i++) usleep(1000);
    }

The printf() is being run as fast as it can, it seems - ie. the usleep()
call doesn't delay the execution at all.  If I change the usleep argument
to 100000, I get a delay - but I need 1 ms delays, not 100 ms ones.

I am running the programs in a dos window of win95 on a 486/80.  How can
I create a delay of 1 ms - which is 1 ms on every machine from the lowliest
386 to the fastest K6/233?

Another problem: If I hit ctrl-c while the machine is executing a long
usleep(), I get a software error message from win 95 ("this program has
performed an illegal operation an dwill be terminated" or some such).
Is there a bug in the djgpp libraries or am I doing something wrong?
(Even the loop above causes the problem, so I don't think the bug is in
my code.)

I'm using gcc2721b.zip, if that matters.

Thanks in advance,

  -jm

-- 

                       1503 kHz @ 22:30 EET DST Mon-Fri

                     ---> http://www.jmp.fi/~jmarin/ <---

- Raw text -