4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2004 Develer S.r.l. (http://www.develer.com/)
30 * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
33 * \brief Heap subsystem (public interface).
35 * \version $Id: heap.c 1532 2008-08-04 07:21:26Z bernie $
36 * \author Bernie Innocenti <bernie@codewiz.org>
41 #include <cfg/macros.h> // IS_POW2()
42 #include <cfg/debug.h> // ASSERT()
44 #include <string.h> // memset()
46 /* NOTE: struct size must be a 2's power! */
47 typedef struct _MemChunk
49 struct _MemChunk *next;
53 STATIC_ASSERT(IS_POW2(sizeof(MemChunk)));
55 #define FREE_FILL_CODE 0xDEAD
56 #define ALLOC_FILL_CODE 0xBEEF
58 void heap_init(struct Heap* h, void* memory, size_t size)
61 memset(memory, FREE_FILL_CODE, size);
64 /* Initialize heap with a single big chunk */
65 h->FreeList = (MemChunk *)memory;
66 h->FreeList->next = NULL;
67 h->FreeList->size = size;
71 void *heap_allocmem(struct Heap* h, size_t size)
73 MemChunk *chunk, *prev;
75 /* Round size up to the allocation granularity */
76 size = ROUND2(size, sizeof(MemChunk));
78 /* Handle allocations of 0 bytes */
80 size = sizeof(MemChunk);
82 /* Walk on the free list looking for any chunk big enough to
83 * fit the requested block size.
85 for (prev = (MemChunk *)&h->FreeList, chunk = h->FreeList;
87 prev = chunk, chunk = chunk->next)
89 if (chunk->size >= size)
91 if (chunk->size == size)
93 /* Just remove this chunk from the free list */
94 prev->next = chunk->next;
96 memset(chunk, ALLOC_FILL_CODE, size);
102 /* Allocate from the END of an existing chunk */
105 memset((uint8_t *)chunk + chunk->size, ALLOC_FILL_CODE, size);
107 return (void *)((uint8_t *)chunk + chunk->size);
112 return NULL; /* fail */
116 void heap_freemem(struct Heap* h, void *mem, size_t size)
122 memset(mem, FREE_FILL_CODE, size);
125 /* Round size up to the allocation granularity */
126 size = ROUND2(size, sizeof(MemChunk));
128 /* Handle allocations of 0 bytes */
130 size = sizeof(MemChunk);
132 /* Special case: first chunk in the free list */
133 ASSERT((uint8_t*)mem != (uint8_t*)h->FreeList);
134 if (((uint8_t *)mem) < ((uint8_t *)h->FreeList))
136 /* Insert memory block before the current free list head */
137 prev = (MemChunk *)mem;
138 prev->next = h->FreeList;
142 else /* Normal case: not the first chunk in the free list */
145 * Walk on the free list. Stop at the insertion point (when mem
146 * is between prev and prev->next)
149 while (prev->next < (MemChunk *)mem && prev->next)
152 /* Make sure mem is not *within* prev */
153 ASSERT((uint8_t*)mem >= (uint8_t*)prev + prev->size);
155 /* Should it be merged with previous block? */
156 if (((uint8_t *)prev) + prev->size == ((uint8_t *)mem))
161 else /* not merged with previous chunk */
163 MemChunk *curr = (MemChunk*)mem;
165 /* insert it after the previous node
166 * and move the 'prev' pointer forward
167 * for the following operations
169 curr->next = prev->next;
173 /* Adjust for the following test */
178 /* Also merge with next chunk? */
179 if (((uint8_t *)prev) + prev->size == ((uint8_t *)prev->next))
181 prev->size += prev->next->size;
182 prev->next = prev->next->next;
184 /* There should be only one merge opportunity, becuase we always merge on free */
185 ASSERT((uint8_t*)prev + prev->size != (uint8_t*)prev->next);
189 #if CONFIG_HEAP_MALLOC
191 void *heap_malloc(struct Heap* h, size_t size)
195 size += sizeof(size_t);
196 if ((mem = (size_t*)heap_allocmem(h, size)))
202 void *heap_calloc(struct Heap* h, size_t size)
206 if ((mem = heap_malloc(h, size)))
207 memset(mem, 0, size);
213 * Free a block of memory, determining its size automatically.
215 * \param h Heap from which the block was allocated.
216 * \param mem Pointer to a block of memory previously allocated with
217 * either heap_malloc() or heap_calloc().
219 * \note If \a mem is a NULL pointer, no operation is performed.
221 * \note Freeing the same memory block twice has undefined behavior.
223 * \note This function works like the ANSI C free().
225 void heap_free(struct Heap *h, void *mem)
227 size_t *_mem = (size_t *)mem;
232 heap_freemem(h, _mem, *_mem);
236 #endif /* CONFIG_HEAP_MALLOC */