ANSI

[unix-history] / usr / src / usr.bin / window / wwrint.c

/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Edward Wang at The University of California, Berkeley.
*
* %sccs.include.redist.c%
*/

#ifndef lint
static char sccsid[] = "@(#)wwrint.c    3.11 (Berkeley) %G%";
#endif /* not lint */

#include "ww.h"
#include <fcntl.h>

/*
* Tty input interrupt handler.
* (1) Read input into buffer (wwib*).
* (2) Set the interrupt flag if anything is read.
* Currently, the last is used to get out of the blocking
* select() in wwiomux().
* To avoid race conditions, we only modify wwibq in here, except
* when the buffer is empty; and everywhere else, we only change wwibp.
* It should be completely safe.
*/
void
wwrint()
{
       register n;

       if (wwibp == wwibq)
               wwibp = wwibq = wwib;
       wwnread++;
       (void) fcntl(0, F_SETFL, FNDELAY|wwnewtty.ww_fflags);
       n = read(0, wwibq, wwibe - wwibq);
       (void) fcntl(0, F_SETFL, wwnewtty.ww_fflags);
       if (n > 0) {
               wwibq += n;
               wwnreadc += n;
               wwsetintr();
       } else if (n == 0)
               wwnreadz++;
       else
               wwnreade++;
}