xref: /titanic_41/usr/src/cmd/sh/stak.c (revision 1573d361e97690e67db291a1e0dc9a9b58f73fd8)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
27 /*	  All Rights Reserved  	*/
28 
29 #pragma ident	"%Z%%M%	%I%	%E% SMI"
30 /*
31  * UNIX shell
32  */
33 
34 #include	"defs.h"
35 
36 
37 /* ========	storage allocation	======== */
38 
39 unsigned char *
getstak(asize)40 getstak(asize)			/* allocate requested stack */
41 int	asize;
42 {
43 	unsigned char	*oldstak;
44 	int		size;
45 
46 	size = round(asize, BYTESPERWORD);
47 	oldstak = stakbot;
48 	staktop = stakbot += size;
49 	if (staktop >= brkend)
50 		growstak(staktop);
51 	return(oldstak);
52 }
53 
54 /*
55  * set up stack for local use
56  * should be followed by `endstak'
57  */
58 unsigned char *
locstak()59 locstak()
60 {
61 	if (brkend - stakbot < BRKINCR)
62 	{
63 		if (setbrk(brkincr) == -1)
64 			error(nostack);
65 		if (brkincr < BRKMAX)
66 			brkincr += 256;
67 	}
68 	return(stakbot);
69 }
70 
71 void
growstak(newtop)72 growstak(newtop)
73 unsigned char	*newtop;
74 {
75 	unsigned	incr;
76 
77 	incr = (unsigned)round(newtop - brkend + 1, BYTESPERWORD);
78 	if (brkincr > incr)
79 		incr = brkincr;
80 	if (setbrk(incr) == -1)
81 		error(nospace);
82 }
83 
84 unsigned char *
savstak()85 savstak()
86 {
87 	assert(staktop == stakbot);
88 	return(stakbot);
89 }
90 
91 unsigned char *
endstak(unsigned char * argp)92 endstak(unsigned char *argp)		/* tidy up after `locstak' */
93 {
94 	unsigned char	*oldstak;
95 
96 	if (argp >= brkend)
97 		growstak(argp);
98 	*argp++ = 0;
99 	oldstak = stakbot;
100 	stakbot = staktop = (unsigned char *)round(argp, BYTESPERWORD);
101 	if (staktop >= brkend)
102 		growstak(staktop);
103 	return(oldstak);
104 }
105 
106 void
tdystak(unsigned char * x)107 tdystak(unsigned char	*x)		/* try to bring stack back to x */
108 {
109 	struct blk *next;
110 
111 	while ((unsigned char *)stakbsy > x)
112 	{
113 		next = stakbsy->word;
114 		free(stakbsy);
115 		stakbsy = next;
116 	}
117 	staktop = stakbot = max(x, stakbas);
118 	rmtemp(x);
119 }
120 
121 void
stakchk(void)122 stakchk(void)
123 {
124 	if ((brkend - stakbas) > BRKINCR + BRKINCR)
125 		setbrk(-BRKINCR);
126 }
127 
128 unsigned char *
cpystak(x)129 cpystak(x)
130 unsigned char	*x;
131 {
132 	return(endstak(movstrstak(x, locstak())));
133 }
134 
135 unsigned char *
movstrstak(unsigned char * a,unsigned char * b)136 movstrstak(unsigned char *a, unsigned char *b)
137 {
138 	do
139 	{
140 		if (b >= brkend)
141 			growstak(b);
142 	}
143 	while (*b++ = *a++);
144 	return(--b);
145 }
146 
147 /*
148  * Copy s2 to s1, always copy n bytes.
149  * Return s1
150  */
151 unsigned char *
memcpystak(unsigned char * s1,unsigned char * s2,int n)152 memcpystak(unsigned char *s1, unsigned char *s2, int n)
153 {
154 	unsigned char *os1 = s1;
155 
156 	while (--n >= 0) {
157 		if (s1 >= brkend)
158 			growstak(s1);
159 		*s1++ = *s2++;
160 	}
161 	return (os1);
162 }
163