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event.c revision 1.1 
      1 /*
      2  * Copyright (c) 1992, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * This software was developed by the Computer Systems Engineering group
      6  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      7  * contributed to Berkeley.
      8  *
      9  * All advertising materials mentioning features or use of this software
     10  * must display the following acknowledgement:
     11  *	This product includes software developed by the University of
     12  *	California, Lawrence Berkeley Laboratory.
     13  *
     14  * Redistribution and use in source and binary forms, with or without
     15  * modification, are permitted provided that the following conditions
     16  * are met:
     17  * 1. Redistributions of source code must retain the above copyright
     18  *    notice, this list of conditions and the following disclaimer.
     19  * 2. Redistributions in binary form must reproduce the above copyright
     20  *    notice, this list of conditions and the following disclaimer in the
     21  *    documentation and/or other materials provided with the distribution.
     22  * 3. All advertising materials mentioning features or use of this software
     23  *    must display the following acknowledgement:
     24  *	This product includes software developed by the University of
     25  *	California, Berkeley and its contributors.
     26  * 4. Neither the name of the University nor the names of its contributors
     27  *    may be used to endorse or promote products derived from this software
     28  *    without specific prior written permission.
     29  *
     30  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     31  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     32  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     33  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     34  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     35  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     36  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     37  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     38  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     39  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     40  * SUCH DAMAGE.
     41  *
     42  *	@(#)event.c	8.1 (Berkeley) 6/11/93
     43  *
     44  * from: Header: event.c,v 1.5 92/11/26 01:10:44 torek Exp  (LBL)
     45  * $Id: event.c,v 1.1 1994/01/26 21:05:41 mw Exp $
     46  */
     47 
     48 /*
     49  * Internal `Firm_event' interface for the keyboard and mouse drivers.
     50  */
     51 
     52 #include "param.h"
     53 #include "fcntl.h"
     54 #include "malloc.h"
     55 #include "proc.h"
     56 #include "systm.h"
     57 #include "vnode.h"
     58 
     59 #include "vuid_event.h"
     60 #include "event_var.h"
     61 
     62 /*
     63  * Initialize a firm_event queue.
     64  */
     65 void
     66 ev_init(ev)
     67 	register struct evvar *ev;
     68 {
     69 
     70 	ev->ev_get = ev->ev_put = 0;
     71 	ev->ev_q = malloc((u_long)EV_QSIZE * sizeof(struct firm_event),
     72 	    M_DEVBUF, M_WAITOK);
     73 	bzero((caddr_t)ev->ev_q, EV_QSIZE * sizeof(struct firm_event));
     74 }
     75 
     76 /*
     77  * Tear down a firm_event queue.
     78  */
     79 void
     80 ev_fini(ev)
     81 	register struct evvar *ev;
     82 {
     83 
     84 	free(ev->ev_q, M_DEVBUF);
     85 }
     86 
     87 /*
     88  * User-level interface: read, select.
     89  * (User cannot write an event queue.)
     90  */
     91 int
     92 ev_read(ev, uio, flags)
     93 	register struct evvar *ev;
     94 	struct uio *uio;
     95 	int flags;
     96 {
     97 	int s, n, cnt, error;
     98 
     99 	/*
    100 	 * Make sure we can return at least 1.
    101 	 */
    102 	if (uio->uio_resid < sizeof(struct firm_event))
    103 		return (EMSGSIZE);	/* ??? */
    104 	s = splev();
    105 	while (ev->ev_get == ev->ev_put) {
    106 		if (flags & IO_NDELAY) {
    107 			splx(s);
    108 			return (EWOULDBLOCK);
    109 		}
    110 		ev->ev_wanted = 1;
    111 		error = tsleep((caddr_t)ev, PEVENT | PCATCH, "firm_event", 0);
    112 		if (error) {
    113 			splx(s);
    114 			return (error);
    115 		}
    116 	}
    117 	/*
    118 	 * Move firm_events from tail end of queue (there is at least one
    119 	 * there).
    120 	 */
    121 	if (ev->ev_put < ev->ev_get)
    122 		cnt = EV_QSIZE - ev->ev_get;	/* events in [get..QSIZE) */
    123 	else
    124 		cnt = ev->ev_put - ev->ev_get;	/* events in [get..put) */
    125 	splx(s);
    126 	n = howmany(uio->uio_resid, sizeof(struct firm_event));
    127 	if (cnt > n)
    128 		cnt = n;
    129 	error = uiomove((caddr_t)&ev->ev_q[ev->ev_get],
    130 	    cnt * sizeof(struct firm_event), uio);
    131 	n -= cnt;
    132 	/*
    133 	 * If we do not wrap to 0, used up all our space, or had an error,
    134 	 * stop.  Otherwise move from front of queue to put index, if there
    135 	 * is anything there to move.
    136 	 */
    137 	if ((ev->ev_get = (ev->ev_get + cnt) % EV_QSIZE) != 0 ||
    138 	    n == 0 || error || (cnt = ev->ev_put) == 0)
    139 		return (error);
    140 	if (cnt > n)
    141 		cnt = n;
    142 	error = uiomove((caddr_t)&ev->ev_q[0],
    143 	    cnt * sizeof(struct firm_event), uio);
    144 	ev->ev_get = cnt;
    145 	return (error);
    146 }
    147 
    148 int
    149 ev_select(ev, rw, p)
    150 	register struct evvar *ev;
    151 	int rw;
    152 	struct proc *p;
    153 {
    154 	int s = splev();
    155 
    156 	switch (rw) {
    157 
    158 	case FREAD:
    159 		/* succeed if there is something to read */
    160 		if (ev->ev_get != ev->ev_put) {
    161 			splx(s);
    162 			return (1);
    163 		}
    164 		selrecord(p, &ev->ev_sel);
    165 		break;
    166 
    167 	case FWRITE:
    168 		return (1);	/* always fails => never blocks */
    169 	}
    170 	splx(s);
    171 	return (0);
    172 }
    173