xref: /titanic_44/usr/src/cmd/sh/stak.c (revision 6927f468b0af7710df000f6b16f6ee413e1e3007)
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, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 1992 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 /*
32  * UNIX shell
33  */
34 
35 #include	"defs.h"
36 
37 
38 /* ========	storage allocation	======== */
39 
40 unsigned char *
41 getstak(asize)			/* allocate requested stack */
42 int	asize;
43 {
44 	unsigned char	*oldstak;
45 	int		size;
46 
47 	size = round(asize, BYTESPERWORD);
48 	oldstak = stakbot;
49 	staktop = stakbot += size;
50 	if (staktop >= brkend)
51 		growstak(staktop);
52 	return(oldstak);
53 }
54 
55 /*
56  * set up stack for local use
57  * should be followed by `endstak'
58  */
59 unsigned char *
60 locstak()
61 {
62 	if (brkend - stakbot < BRKINCR)
63 	{
64 		if (setbrk(brkincr) == -1)
65 			error(nostack);
66 		if (brkincr < BRKMAX)
67 			brkincr += 256;
68 	}
69 	return(stakbot);
70 }
71 
72 void
73 growstak(newtop)
74 unsigned char	*newtop;
75 {
76 	unsigned	incr;
77 
78 	incr = (unsigned)round(newtop - brkend + 1, BYTESPERWORD);
79 	if (brkincr > incr)
80 		incr = brkincr;
81 	if (setbrk(incr) == -1)
82 		error(nospace);
83 }
84 
85 unsigned char *
86 savstak()
87 {
88 	assert(staktop == stakbot);
89 	return(stakbot);
90 }
91 
92 unsigned char *
93 endstak(unsigned char *argp)		/* tidy up after `locstak' */
94 {
95 	unsigned char	*oldstak;
96 
97 	if (argp >= brkend)
98 		growstak(argp);
99 	*argp++ = 0;
100 	oldstak = stakbot;
101 	stakbot = staktop = (unsigned char *)round(argp, BYTESPERWORD);
102 	if (staktop >= brkend)
103 		growstak(staktop);
104 	return(oldstak);
105 }
106 
107 void
108 tdystak(unsigned char	*x)		/* try to bring stack back to x */
109 {
110 	while ((unsigned char *)stakbsy > x)
111 	{
112 		free(stakbsy);
113 		stakbsy = stakbsy->word;
114 	}
115 	staktop = stakbot = max(x, stakbas);
116 	rmtemp(x);
117 }
118 
119 void
120 stakchk(void)
121 {
122 	if ((brkend - stakbas) > BRKINCR + BRKINCR)
123 		setbrk(-BRKINCR);
124 }
125 
126 unsigned char *
127 cpystak(x)
128 unsigned char	*x;
129 {
130 	return(endstak(movstrstak(x, locstak())));
131 }
132 
133 unsigned char *
134 movstrstak(unsigned char *a, unsigned char *b)
135 {
136 	do
137 	{
138 		if (b >= brkend)
139 			growstak(b);
140 	}
141 	while (*b++ = *a++);
142 	return(--b);
143 }
144 
145 /*
146  * Copy s2 to s1, always copy n bytes.
147  * Return s1
148  */
149 unsigned char *
150 memcpystak(unsigned char *s1, unsigned char *s2, int n)
151 {
152 	unsigned char *os1 = s1;
153 
154 	while (--n >= 0) {
155 		if (s1 >= brkend)
156 			growstak(s1);
157 		*s1++ = *s2++;
158 	}
159 	return (os1);
160 }
161