1 /***********************************************************************
2 * *
3 * This software is part of the ast package *
4 * Copyright (c) 1985-2010 AT&T Intellectual Property *
5 * and is licensed under the *
6 * Common Public License, Version 1.0 *
7 * by AT&T Intellectual Property *
8 * *
9 * A copy of the License is available at *
10 * http://www.opensource.org/licenses/cpl1.0.txt *
11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
12 * *
13 * Information and Software Systems Research *
14 * AT&T Research *
15 * Florham Park NJ *
16 * *
17 * Glenn Fowler <gsf@research.att.com> *
18 * David Korn <dgk@research.att.com> *
19 * Phong Vo <kpv@research.att.com> *
20 * *
21 ***********************************************************************/
22 #pragma prototyped
23 /*
24 * pointer stack routines
25 */
26
27 static const char id_stack[] = "\n@(#)$Id: stack (AT&T Bell Laboratories) 1984-05-01 $\0\n";
28
29 #include <ast.h>
30 #include <stack.h>
31
32 /*
33 * create a new stack
34 */
35
36 STACK
stackalloc(register int size,void * error)37 stackalloc(register int size, void* error)
38 {
39 register STACK stack;
40 register struct stackblock *b;
41
42 if (size <= 0) size = 100;
43 if (!(stack = newof(0, struct stacktable, 1, 0))) return(0);
44 if (!(b = newof(0, struct stackblock, 1, 0)))
45 {
46 free(stack);
47 return(0);
48 }
49 if (!(b->stack = newof(0, void*, size, 0)))
50 {
51 free(b);
52 free(stack);
53 return(0);
54 }
55 stack->blocks = b;
56 stack->size = size;
57 stack->error = error;
58 stack->position.block = b;
59 stack->position.index = -1;
60 b->next = 0;
61 b->prev = 0;
62 return(stack);
63 }
64
65 /*
66 * remove a stack
67 */
68
69 void
stackfree(register STACK stack)70 stackfree(register STACK stack)
71 {
72 register struct stackblock* b;
73 register struct stackblock* p;
74
75 b = stack->blocks;
76 while (p = b)
77 {
78 b = p->next;
79 free(p->stack);
80 free(p);
81 }
82 free(stack);
83 }
84
85 /*
86 * clear stack
87 */
88
89 void
stackclear(register STACK stack)90 stackclear(register STACK stack)
91 {
92 stack->position.block = stack->blocks;
93 stack->position.index = -1;
94 }
95
96 /*
97 * get value on top of stack
98 */
99
100 void*
stackget(register STACK stack)101 stackget(register STACK stack)
102 {
103 if (stack->position.index < 0) return(stack->error);
104 else return(stack->position.block->stack[stack->position.index]);
105 }
106
107 /*
108 * push value on to stack
109 */
110
111 int
stackpush(register STACK stack,void * value)112 stackpush(register STACK stack, void* value)
113 {
114 register struct stackblock *b;
115
116 if (++stack->position.index >= stack->size)
117 {
118 b = stack->position.block;
119 if (b->next) b = b->next;
120 else
121 {
122 if (!(b->next = newof(0, struct stackblock, 1, 0)))
123 return(-1);
124 b = b->next;
125 if (!(b->stack = newof(0, void*, stack->size, 0)))
126 return(-1);
127 b->prev = stack->position.block;
128 b->next = 0;
129 }
130 stack->position.block = b;
131 stack->position.index = 0;
132 }
133 stack->position.block->stack[stack->position.index] = value;
134 return(0);
135 }
136
137 /*
138 * pop value off stack
139 */
140
141 int
stackpop(register STACK stack)142 stackpop(register STACK stack)
143 {
144 /*
145 * return:
146 *
147 * -1 if stack empty before pop
148 * 0 if stack empty after pop
149 * 1 if stack not empty before & after pop
150 */
151
152 if (stack->position.index < 0) return(-1);
153 else if (--stack->position.index < 0)
154 {
155 if (!stack->position.block->prev) return(0);
156 stack->position.block = stack->position.block->prev;
157 stack->position.index = stack->size - 1;
158 return(1);
159 }
160 else return(1);
161 }
162
163 /*
164 * set|get stack position
165 */
166
167 void
stacktell(register STACK stack,int set,STACKPOS * position)168 stacktell(register STACK stack, int set, STACKPOS* position)
169 {
170 if (set) stack->position = *position;
171 else *position = stack->position;
172 }
173