sys/kern/tty_ring.c

/*
 * Copyright (c) 1989, 1990, 1991, 1992 William F. Jolitz, TeleMuse
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This software is a component of "386BSD" developed by
 *      William F. Jolitz, TeleMuse.
 * 4. Neither the name of the developer nor the name "386BSD"
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS A COMPONENT OF 386BSD DEVELOPED BY WILLIAM F. JOLITZ
 * AND IS INTENDED FOR RESEARCH AND EDUCATIONAL PURPOSES ONLY. THIS
 * SOFTWARE SHOULD NOT BE CONSIDERED TO BE A COMMERCIAL PRODUCT.
 * THE DEVELOPER URGES THAT USERS WHO REQUIRE A COMMERCIAL PRODUCT
 * NOT MAKE USE OF THIS WORK.
 *
 * FOR USERS WHO WISH TO UNDERSTAND THE 386BSD SYSTEM DEVELOPED
 * BY WILLIAM F. JOLITZ, WE RECOMMEND THE USER STUDY WRITTEN
 * REFERENCES SUCH AS THE  "PORTING UNIX TO THE 386" SERIES
 * (BEGINNING JANUARY 1991 "DR. DOBBS JOURNAL", USA AND BEGINNING
 * JUNE 1991 "UNIX MAGAZIN", GERMANY) BY WILLIAM F. JOLITZ AND
 * LYNNE GREER JOLITZ, AS WELL AS OTHER BOOKS ON UNIX AND THE
 * ON-LINE 386BSD USER MANUAL BEFORE USE. A BOOK DISCUSSING THE INTERNALS
 * OF 386BSD ENTITLED "386BSD FROM THE INSIDE OUT" WILL BE AVAILABLE LATE 1992.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPER ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE DEVELOPER BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *
 * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
 * --------------------         -----   ----------------------
 * CURRENT PATCH LEVEL:         2       00163
 * --------------------         -----   ----------------------
 *
 * 14 Mar 93    David Greenman          Upgrade bpf to match tcpdump 2.2.1
 * 27 May 93    Bruce Evans             Who really did the changes that David
 *                                      supplied in the 14 Mar 93 patch.
 */
static char rcsid[] = "$Header: /usr/bill/working/sys/kern/RCS/tty_ring.c,v 1.2 92/01/21 21:29:55 william Exp $";

#include "param.h"
#include "systm.h"
#include "buf.h"
#include "ioctl.h"
#include "tty.h"

/*
 * XXX - put this in tty.h someday.
 */
size_t rb_write __P((struct ringb *to, char *buf, size_t nfrom));

putc(c, rbp) struct ringb *rbp;
{
        char *nxtp;

        /* ring buffer full? */
        if ( (nxtp = RB_SUCC(rbp, rbp->rb_tl)) == rbp->rb_hd) return (-1);

        /* stuff character */
        *rbp->rb_tl = c;
        rbp->rb_tl = nxtp;
        return(0);
}

getc(rbp) struct ringb *rbp;
{
        u_char c;

        /* ring buffer empty? */
        if (rbp->rb_hd == rbp->rb_tl) return(-1);

        /* fetch character, locate next character */
        c = *(u_char *) rbp->rb_hd;
        rbp->rb_hd = RB_SUCC(rbp, rbp->rb_hd);
        return (c);
}

nextc(cpp, rbp) struct ringb *rbp; char **cpp; {

        if (*cpp == rbp->rb_tl) return (0);
        else {  char *cp;
                cp = *cpp;
                *cpp = RB_SUCC(rbp, cp);
                return(*cp);
        }
}

ungetc(c, rbp) struct ringb *rbp;
{
        char    *backp;

        /* ring buffer full? */
        if ( (backp = RB_PRED(rbp, rbp->rb_hd)) == rbp->rb_tl) return (-1);
        rbp->rb_hd = backp;

        /* stuff character */
        *rbp->rb_hd = c;
        return(0);
}

unputc(rbp) struct ringb *rbp;
{
        char    *backp;
        int c;

        /* ring buffer empty? */
        if (rbp->rb_hd == rbp->rb_tl) return(-1);

        /* backup buffer and dig out previous character */
        backp = RB_PRED(rbp, rbp->rb_tl);
        c = *(u_char *)backp;
        rbp->rb_tl = backp;

        return(c);
}

#define peekc(rbp)      (*(rbp)->rb_hd)

initrb(rbp) struct ringb *rbp; {
        rbp->rb_hd = rbp->rb_tl = rbp->rb_buf;
}

/*
 * Example code for contiguous operations:
        ...
        nc = RB_CONTIGPUT(&rb);
        if (nc) {
        if (nc > 9) nc = 9;
                bcopy("ABCDEFGHI", rb.rb_tl, nc);
                rb.rb_tl += nc;
                rb.rb_tl = RB_ROLLOVER(&rb, rb.rb_tl);
        }
        ...
        ...
        nc = RB_CONTIGGET(&rb);
        if (nc) {
                if (nc > 79) nc = 79;
                bcopy(rb.rb_hd, stringbuf, nc);
                rb.rb_hd += nc;
                rb.rb_hd = RB_ROLLOVER(&rb, rb.rb_hd);
                stringbuf[nc] = 0;
                printf("%s|", stringbuf);
        }
        ...
 */

/*
 * Concatenate ring buffers.
 */
catb(from, to)
        struct ringb *from, *to;
{
        size_t nfromleft;
        size_t nfromright;

        nfromright = RB_CONTIGGET(from);
        rb_write(to, from->rb_hd, nfromright);
        from->rb_hd += nfromright;
        from->rb_hd = RB_ROLLOVER(from, from->rb_hd);
        nfromleft = RB_CONTIGGET(from);
        rb_write(to, from->rb_hd, nfromleft);
        from->rb_hd += nfromleft;
}

/*
 * Copy ordinary buffer to ring buffer, return count of what fitted.
 */
size_t rb_write(to, buf, nfrom)
        struct ringb *to;
        char *buf;
        size_t nfrom;
{
        char *toleft;
        size_t ntoleft;
        size_t ntoright;

        ntoright = RB_CONTIGPUT(to);
        if (nfrom < ntoright) {
                bcopy(buf, to->rb_tl, nfrom);
                to->rb_tl += nfrom;
                return (nfrom);
        }
        bcopy(buf, to->rb_tl, ntoright);
        nfrom -= ntoright;
        toleft = to->rb_buf;    /* fast RB_ROLLOVER */
        ntoleft = to->rb_hd - toleft;   /* fast RB_CONTIGPUT */
        if (nfrom > ntoleft)
                nfrom = ntoleft;
        bcopy(buf + ntoright, toleft, nfrom);
        to->rb_tl = toleft + nfrom;
        return (ntoright + nfrom);
}