/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

/*
 * 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 */
{
        struct blk *next;

        while ((unsigned char *)stakbsy > x)
        {
                next = stakbsy->word;
                free(stakbsy);
                stakbsy = next;
        }
        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);
}