Re: [PARPORT] new library 'parapin' for parallel port programming

From: Jeremy Elson (
Date: Thu Jun 15 2000 - 10:16:51 EDT

  • Next message: Tim Waugh: "Re: [PARPORT] new library 'parapin' for parallel port programming"

    Tim Waugh writes:

    >On Wed, Jun 14, 2000 at 06:59:19PM -0700, Jeremy Elson wrote:
    >> "parapin" ( is a
    >> parallel port programming library for Linux. The library makes it
    >> easy to write C code under Linux that controls individual pins on a PC
    >> parallel port.
    >What's the license?
    >There are some enhancements that it would be good to make..

    Oops... it is GPL, and it just occurred to me that I did not actually
    say that explicitly in the documentation.

    There are at least a couple of enhancements I have in mind also that
    I'd like to get around to eventually. Mainly:

    1- support for more than one parallel port in the kernel-module version.
       Probably, the initialization function should give you a handle
       which you then pass back to it with all the other functions.
       Unfortunately this breaks the interface, or adds new functions to it.

       The current version grew out of what was only a user-space library,
       where this was less of an issue (different processes would have
       different instances of the library, so could be using a different
       ports. Although, even in this case, you're out of luck if one
       process wants to use more than one port).

    2- Support for finer-grained timing in the user-space library.
       Basically a reimplementation in userspace of the kernel's bogomips
       calcluation and udelay() busy-wait loop. Of course, it won't be as
       exact as the kernel's udelay() due to interrupt handling and other
       processes being scheduled. But, doing delays using system calls
       (e.g. sleep()) doesn't work if you want to wait for less than 1
       jiffy (10ms on the 386).


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