1 /*! \file btGenericPoolAllocator.cpp
2 \author Francisco Leon Najera. email projectileman@yahoo.com
3
4 General purpose allocator class
5 */
6 /*
7 Bullet Continuous Collision Detection and Physics Library
8 Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
9
10 This software is provided 'as-is', without any express or implied warranty.
11 In no event will the authors be held liable for any damages arising from the use of this software.
12 Permission is granted to anyone to use this software for any purpose,
13 including commercial applications, and to alter it and redistribute it freely,
14 subject to the following restrictions:
15
16 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
17 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
18 3. This notice may not be removed or altered from any source distribution.
19 */
20
21 #include "btGenericPoolAllocator.h"
22
23 /// *************** btGenericMemoryPool ******************///////////
24
allocate_from_free_nodes(size_t num_elements)25 size_t btGenericMemoryPool::allocate_from_free_nodes(size_t num_elements)
26 {
27 size_t ptr = BT_UINT_MAX;
28
29 if (m_free_nodes_count == 0) return BT_UINT_MAX;
30 // find an avaliable free node with the correct size
31 size_t revindex = m_free_nodes_count;
32
33 while (revindex-- && ptr == BT_UINT_MAX)
34 {
35 if (m_allocated_sizes[m_free_nodes[revindex]] >= num_elements)
36 {
37 ptr = revindex;
38 }
39 }
40 if (ptr == BT_UINT_MAX) return BT_UINT_MAX; // not found
41
42 revindex = ptr;
43 ptr = m_free_nodes[revindex];
44 // post: ptr contains the node index, and revindex the index in m_free_nodes
45
46 size_t finalsize = m_allocated_sizes[ptr];
47 finalsize -= num_elements;
48
49 m_allocated_sizes[ptr] = num_elements;
50
51 // post: finalsize>=0, m_allocated_sizes[ptr] has the requested size
52
53 if (finalsize > 0) // preserve free node, there are some free memory
54 {
55 m_free_nodes[revindex] = ptr + num_elements;
56 m_allocated_sizes[ptr + num_elements] = finalsize;
57 }
58 else // delete free node
59 {
60 // swap with end
61 m_free_nodes[revindex] = m_free_nodes[m_free_nodes_count - 1];
62 m_free_nodes_count--;
63 }
64
65 return ptr;
66 }
67
allocate_from_pool(size_t num_elements)68 size_t btGenericMemoryPool::allocate_from_pool(size_t num_elements)
69 {
70 if (m_allocated_count + num_elements > m_max_element_count) return BT_UINT_MAX;
71
72 size_t ptr = m_allocated_count;
73
74 m_allocated_sizes[m_allocated_count] = num_elements;
75 m_allocated_count += num_elements;
76
77 return ptr;
78 }
79
init_pool(size_t element_size,size_t element_count)80 void btGenericMemoryPool::init_pool(size_t element_size, size_t element_count)
81 {
82 m_allocated_count = 0;
83 m_free_nodes_count = 0;
84
85 m_element_size = element_size;
86 m_max_element_count = element_count;
87
88 m_pool = (unsigned char *)btAlignedAlloc(m_element_size * m_max_element_count, 16);
89 m_free_nodes = (size_t *)btAlignedAlloc(sizeof(size_t) * m_max_element_count, 16);
90 m_allocated_sizes = (size_t *)btAlignedAlloc(sizeof(size_t) * m_max_element_count, 16);
91
92 for (size_t i = 0; i < m_max_element_count; i++)
93 {
94 m_allocated_sizes[i] = 0;
95 }
96 }
97
end_pool()98 void btGenericMemoryPool::end_pool()
99 {
100 btAlignedFree(m_pool);
101 btAlignedFree(m_free_nodes);
102 btAlignedFree(m_allocated_sizes);
103 m_allocated_count = 0;
104 m_free_nodes_count = 0;
105 }
106
107 //! Allocates memory in pool
108 /*!
109 \param size_bytes size in bytes of the buffer
110 */
allocate(size_t size_bytes)111 void *btGenericMemoryPool::allocate(size_t size_bytes)
112 {
113 size_t module = size_bytes % m_element_size;
114 size_t element_count = size_bytes / m_element_size;
115 if (module > 0) element_count++;
116
117 size_t alloc_pos = allocate_from_free_nodes(element_count);
118 // a free node is found
119 if (alloc_pos != BT_UINT_MAX)
120 {
121 return get_element_data(alloc_pos);
122 }
123 // allocate directly on pool
124 alloc_pos = allocate_from_pool(element_count);
125
126 if (alloc_pos == BT_UINT_MAX) return NULL; // not space
127 return get_element_data(alloc_pos);
128 }
129
freeMemory(void * pointer)130 bool btGenericMemoryPool::freeMemory(void *pointer)
131 {
132 unsigned char *pointer_pos = (unsigned char *)pointer;
133 unsigned char *pool_pos = (unsigned char *)m_pool;
134 // calc offset
135 if (pointer_pos < pool_pos) return false; //other pool
136 size_t offset = size_t(pointer_pos - pool_pos);
137 if (offset >= get_pool_capacity()) return false; // far away
138
139 // find free position
140 m_free_nodes[m_free_nodes_count] = offset / m_element_size;
141 m_free_nodes_count++;
142 return true;
143 }
144
145 /// *******************! btGenericPoolAllocator *******************!///
146
~btGenericPoolAllocator()147 btGenericPoolAllocator::~btGenericPoolAllocator()
148 {
149 // destroy pools
150 size_t i;
151 for (i = 0; i < m_pool_count; i++)
152 {
153 m_pools[i]->end_pool();
154 btAlignedFree(m_pools[i]);
155 }
156 }
157
158 // creates a pool
push_new_pool()159 btGenericMemoryPool *btGenericPoolAllocator::push_new_pool()
160 {
161 if (m_pool_count >= BT_DEFAULT_MAX_POOLS) return NULL;
162
163 btGenericMemoryPool *newptr = (btGenericMemoryPool *)btAlignedAlloc(sizeof(btGenericMemoryPool), 16);
164
165 m_pools[m_pool_count] = newptr;
166
167 m_pools[m_pool_count]->init_pool(m_pool_element_size, m_pool_element_count);
168
169 m_pool_count++;
170 return newptr;
171 }
172
failback_alloc(size_t size_bytes)173 void *btGenericPoolAllocator::failback_alloc(size_t size_bytes)
174 {
175 btGenericMemoryPool *pool = NULL;
176
177 if (size_bytes <= get_pool_capacity())
178 {
179 pool = push_new_pool();
180 }
181
182 if (pool == NULL) // failback
183 {
184 return btAlignedAlloc(size_bytes, 16);
185 }
186
187 return pool->allocate(size_bytes);
188 }
189
failback_free(void * pointer)190 bool btGenericPoolAllocator::failback_free(void *pointer)
191 {
192 btAlignedFree(pointer);
193 return true;
194 }
195
196 //! Allocates memory in pool
197 /*!
198 \param size_bytes size in bytes of the buffer
199 */
allocate(size_t size_bytes)200 void *btGenericPoolAllocator::allocate(size_t size_bytes)
201 {
202 void *ptr = NULL;
203
204 size_t i = 0;
205 while (i < m_pool_count && ptr == NULL)
206 {
207 ptr = m_pools[i]->allocate(size_bytes);
208 ++i;
209 }
210
211 if (ptr) return ptr;
212
213 return failback_alloc(size_bytes);
214 }
215
freeMemory(void * pointer)216 bool btGenericPoolAllocator::freeMemory(void *pointer)
217 {
218 bool result = false;
219
220 size_t i = 0;
221 while (i < m_pool_count && result == false)
222 {
223 result = m_pools[i]->freeMemory(pointer);
224 ++i;
225 }
226
227 if (result) return true;
228
229 return failback_free(pointer);
230 }
231
232 /// ************** STANDARD ALLOCATOR ***************************///
233
234 #define BT_DEFAULT_POOL_SIZE 32768
235 #define BT_DEFAULT_POOL_ELEMENT_SIZE 8
236
237 // main allocator
238 class GIM_STANDARD_ALLOCATOR : public btGenericPoolAllocator
239 {
240 public:
GIM_STANDARD_ALLOCATOR()241 GIM_STANDARD_ALLOCATOR() : btGenericPoolAllocator(BT_DEFAULT_POOL_ELEMENT_SIZE, BT_DEFAULT_POOL_SIZE)
242 {
243 }
244 };
245
246 // global allocator
247 GIM_STANDARD_ALLOCATOR g_main_allocator;
248
btPoolAlloc(size_t size)249 void *btPoolAlloc(size_t size)
250 {
251 return g_main_allocator.allocate(size);
252 }
253
btPoolRealloc(void * ptr,size_t oldsize,size_t newsize)254 void *btPoolRealloc(void *ptr, size_t oldsize, size_t newsize)
255 {
256 void *newptr = btPoolAlloc(newsize);
257 size_t copysize = oldsize < newsize ? oldsize : newsize;
258 memcpy(newptr, ptr, copysize);
259 btPoolFree(ptr);
260 return newptr;
261 }
262
btPoolFree(void * ptr)263 void btPoolFree(void *ptr)
264 {
265 g_main_allocator.freeMemory(ptr);
266 }
267