Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!ISUMVS.BITNET!GG.SPY
From: GG.SPY@ISUMVS.BITNET ("John Hascall")
Newsgroups: comp.os.vms
Subject: Re: single char input in VAX C
Message-ID: <8803130715.AA24642@ucbvax.Berkeley.EDU>
Date: 11 Mar 88 14:35:57 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 33

> From:         F026@CPC865.UEA.AC.UK
> Subject:      single char input in VAX C
>
> (as far as I know) the only way you can get single character input on a VAX
> is to use the $QIO (Queued Input/Output) system service, which involves
> setting what is effectively an interrupt vector which you then have to
> service. To make it simpler, VMS also has the $QIOW (QIO with Wait) which
> will wait for your 'interrupt'. Look it up in the System Service Manual.
>
> Mike Salmon

    To elucidate:

    #include <iodef.h>
    #include <descrip.h>
    typedef struct IOSB {
       unsigned short status;
       unsigned short count;
       unsigned long  other;
    } IOSB;
    typedef unsigned short CHANNEL;
    $DESCRIPTOR("TT",tty_name);
    unsigned long status;
    CHANNEL tty_chan;
    IOSB tty_iosb;
    char inchar;

    status = SYS$ASSIGN(&tty_name,&tty_chan);  /* only need to do this once */

    status = SYS$QIOW(0,tty_chan,IO$_READVBLK,&tty_iosb,0,0,&inchar,1,0,0,0,0);

John Hascall
Iowa State University Computation Center
GGUUU@ISUMVS.BITNET