cmd/sh/stak.c

	stak.c revision 965005c81e0f731867d47892b9fb677030b102df
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1992 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

#pragma ident   "%Z%%M% %I% %E% SMI"
/*
 * UNIX shell
 */

#include    "defs.h"


/* ======== storage allocation  ======== */

unsigned char *
getstak(asize)          /* allocate requested stack */
int asize;
{
    unsigned char   *oldstak;
    int     size;

    size = round(asize, BYTESPERWORD);
    oldstak = stakbot;
    staktop = stakbot += size;
    if (staktop >= brkend)
        growstak(staktop);
    return(oldstak);
}

/*
 * set up stack for local use
 * should be followed by `endstak'
 */
unsigned char *
locstak()
{
    if (brkend - stakbot < BRKINCR)
    {
        if (setbrk(brkincr) == -1)
            error(nostack);
        if (brkincr < BRKMAX)
            brkincr += 256;
    }
    return(stakbot);
}

void
growstak(newtop)
unsigned char   *newtop;
{
    unsigned    incr;

    incr = (unsigned)round(newtop - brkend + 1, BYTESPERWORD);
    if (brkincr > incr)
        incr = brkincr;
    if (setbrk(incr) == -1)
        error(nospace);
}

unsigned char *
savstak()
{
    assert(staktop == stakbot);
    return(stakbot);
}

unsigned char *
endstak(unsigned char *argp)        /* tidy up after `locstak' */
{
    unsigned char   *oldstak;

    if (argp >= brkend)
        growstak(argp);
    *argp++ = 0;
    oldstak = stakbot;
    stakbot = staktop = (unsigned char *)round(argp, BYTESPERWORD);
    if (staktop >= brkend)
        growstak(staktop);
    return(oldstak);
}

void
tdystak(unsigned char   *x)     /* try to bring stack back to x */
{
    while ((unsigned char *)stakbsy > x)
    {
        free(stakbsy);
        stakbsy = stakbsy->word;
    }
    staktop = stakbot = max(x, stakbas);
    rmtemp(x);
}

void
stakchk(void)
{
    if ((brkend - stakbas) > BRKINCR + BRKINCR)
        setbrk(-BRKINCR);
}

unsigned char *
cpystak(x)
unsigned char   *x;
{
    return(endstak(movstrstak(x, locstak())));
}

unsigned char *
movstrstak(unsigned char *a, unsigned char *b)
{
    do
    {
        if (b >= brkend)
            growstak(b);
    }
    while (*b++ = *a++);
    return(--b);
}

/*
 * Copy s2 to s1, always copy n bytes.
 * Return s1
 */
unsigned char *
memcpystak(unsigned char *s1, unsigned char *s2, int n)
{
    unsigned char *os1 = s1;

    while (--n >= 0) {
        if (s1 >= brkend)
            growstak(s1);
        *s1++ = *s2++;
    }
    return (os1);
}