1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
3 *
4 * Copyright 2016 Olaf Wintermann. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /**
30 * @file stack.h
31 *
32 * Default stack memory allocation implementation.
33 *
34 * @author Mike Becker
35 * @author Olaf Wintermann
36 */
37
38 #ifndef UCX_STACK_H
39 #define UCX_STACK_H
40
41 #include "ucx.h"
42 #include "allocator.h"
43
44 #ifdef __cplusplus
45 extern "C" {
46 #endif
47
48
49 /**
50 * UCX stack structure.
51 */
52 typedef struct {
53 /** UcxAllocator based on this stack */
54 UcxAllocator allocator;
55
56 /** Stack size. */
57 size_t size;
58
59 /** Pointer to the bottom of the stack */
60 char *space;
61
62 /** Pointer to the top of the stack */
63 char *top;
64 } UcxStack;
65
66 /**
67 * Metadata for each UCX stack element.
68 */
69 struct ucx_stack_metadata {
70 /**
71 * Location of the previous element (<code>NULL</code> if this is the first)
72 */
73 char *prev;
74
75 /** Size of this element */
76 size_t size;
77 };
78
79 /**
80 * Initializes UcxStack structure with memory.
81 *
82 * @param stack a pointer to an uninitialized stack structure
83 * @param space the memory area that shall be managed
84 * @param size size of the memory area
85 * @return a new UcxStack structure
86 */
87 void ucx_stack_init(UcxStack *stack, char* space, size_t size);
88
89 /**
90 * Allocates stack memory.
91 *
92 * @param stack a pointer to the stack
93 * @param n amount of memory to allocate
94 * @return a pointer to the allocated memory
95 * @see ucx_allocator_malloc()
96 */
97 void *ucx_stack_malloc(UcxStack *stack, size_t n);
98
99 /**
100 * Alias for #ucx_stack_malloc().
101 * @param stack a pointer to the stack
102 * @param n amount of memory to allocate
103 * @return a pointer to the allocated memory
104 * @see ucx_stack_malloc
105 */
106 #define ucx_stack_push(stack, n) ucx_stack_malloc(stack, n)
107
108 /**
109 * Allocates an array of stack memory
110 *
111 * The content of the allocated memory is set to zero.
112 *
113 * @param stack a pointer to the stack
114 * @param nelem amount of elements to allocate
115 * @param elsize amount of memory per element
116 * @return a pointer to the allocated memory
117 * @see ucx_allocator_calloc()
118 */
119 void *ucx_stack_calloc(UcxStack *stack, size_t nelem, size_t elsize);
120
121 /**
122 * Alias for #ucx_stack_calloc().
123 *
124 * @param stack a pointer to the stack
125 * @param n amount of elements to allocate
126 * @param elsize amount of memory per element
127 * @return a pointer to the allocated memory
128 * @see ucx_stack_calloc
129 */
130 #define ucx_stack_pusharr(stack,n,elsize) ucx_stack_calloc(stack,n,elssize)
131
132 /**
133 * Reallocates memory on the stack.
134 *
135 * Shrinking memory is always safe. Extending memory can be very expensive.
136 *
137 * @param stack the stack
138 * @param ptr a pointer to the memory that shall be reallocated
139 * @param n the new size of the memory
140 * @return a pointer to the new location of the memory
141 * @see ucx_allocator_realloc()
142 */
143 void *ucx_stack_realloc(UcxStack *stack, void *ptr, size_t n);
144
145 /**
146 * Frees memory on the stack.
147 *
148 * Freeing stack memory behaves in a special way.
149 *
150 * If the element, that should be freed, is the top most element of the stack,
151 * it is removed from the stack. Otherwise it is marked as freed. Marked
152 * elements are removed, when they become the top most elements of the stack.
153 *
154 * @param stack a pointer to the stack
155 * @param ptr a pointer to the memory that shall be freed
156 */
157 void ucx_stack_free(UcxStack *stack, void *ptr);
158
159
160 /**
161 * Returns the size of the top most element.
162 * @param stack a pointer to the stack
163 * @return the size of the top most element
164 */
165 #define ucx_stack_topsize(stack) ((stack)->top ? ((struct ucx_stack_metadata*)\
166 (stack)->top - 1)->size : 0)
167
168 /**
169 * Removes the top most element from the stack and copies the content to <code>
170 * dest</code>, if specified.
171 *
172 * Use #ucx_stack_topsize()# to get the amount of memory that must be available
173 * at the location of <code>dest</code>.
174 *
175 * @param stack a pointer to the stack
176 * @param dest the location where the contents shall be written to, or <code>
177 * NULL</code>, if the element shall only be removed.
178 * @see ucx_stack_free
179 * @see ucx_stack_popn
180 */
181 #define ucx_stack_pop(stack, dest) ucx_stack_popn(stack, dest, (size_t)-1)
182
183 /**
184 * Removes the top most element from the stack and copies the content to <code>
185 * dest</code>.
186 *
187 * In contrast to #ucx_stack_pop() the <code>dest</code> pointer <code>MUST
188 * NOT</code> be <code>NULL</code>.
189 *
190 * @param stack a pointer to the stack
191 * @param dest the location where the contents shall be written to
192 * @param n copies at most n elements to <code>dest</code>
193 * @see ucx_stack_pop
194 */
195 void ucx_stack_popn(UcxStack *stack, void *dest, size_t n);
196
197 /**
198 * Returns the remaining available memory on the specified stack.
199 *
200 * @param stack a pointer to the stack
201 * @return the remaining available memory
202 */
203 size_t ucx_stack_avail(UcxStack *stack);
204
205 /**
206 * Checks, if the stack is empty.
207 *
208 * @param stack a pointer to the stack
209 * @return nonzero, if the stack is empty, zero otherwise
210 */
211 #define ucx_stack_empty(stack) (!(stack)->top)
212
213 /**
214 * Computes a recommended size for the stack memory area. Note, that
215 * reallocations have not been taken into account, so you might need to reserve
216 * twice as much memory to allow many reallocations.
217 *
218 * @param size the approximate payload
219 * @param elems the approximate count of element allocations
220 * @return a recommended size for the stack space based on the information
221 * provided
222 */
223 #define ucx_stack_dim(size, elems) (size+sizeof(struct ucx_stack_metadata) * \
224 (elems + 1))
225
226
227 #ifdef __cplusplus
228 }
229 #endif
230
231 #endif /* UCX_STACK_H */
232
233