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3077abb6 MM |
1 | #include "MemoryPool.h" |
2 | ||
8d54c34c JM |
3 | #include "StreamOutput.h" |
4 | ||
3077abb6 | 5 | #include <mri.h> |
1803076a | 6 | #include <cstdio> |
3077abb6 | 7 | |
78d03fd7 JM |
8 | // this catches all usages of delete blah. The object's destructor is called before we get here |
9 | // it first checks if the deleted object is part of a pool, and uses free otherwise. | |
10 | void operator delete(void* p) | |
11 | { | |
12 | MemoryPool* m = MemoryPool::first; | |
13 | while (m) | |
14 | { | |
15 | if (m->has(p)) | |
16 | { | |
17 | MDEBUG("Pool %p has %p, using dealloc()\n", m, p); | |
18 | m->dealloc(p); | |
19 | return; | |
20 | } | |
21 | m = m->next; | |
22 | } | |
23 | ||
24 | MDEBUG("no pool has %p, using free()\n", p); | |
25 | free(p); | |
26 | } | |
27 | ||
28 | ||
3077abb6 MM |
29 | #define offset(x) (((uint8_t*) x) - ((uint8_t*) this->base)) |
30 | ||
31 | typedef struct __attribute__ ((packed)) | |
32 | { | |
33 | uint32_t next :31; | |
34 | uint32_t used :1; | |
35 | ||
36 | uint8_t data[]; | |
37 | } _poolregion; | |
38 | ||
39 | MemoryPool* MemoryPool::first = NULL; | |
40 | ||
41 | MemoryPool::MemoryPool(void* base, uint16_t size) | |
42 | { | |
43 | this->base = base; | |
44 | this->size = size; | |
56c83a64 | 45 | |
3077abb6 MM |
46 | ((_poolregion*) base)->used = 0; |
47 | ((_poolregion*) base)->next = size; | |
48 | ||
3077abb6 MM |
49 | // insert ourselves into head of LL |
50 | next = first; | |
51 | first = this; | |
52 | } | |
53 | ||
54 | MemoryPool::~MemoryPool() | |
55 | { | |
56 | MDEBUG("Pool %p destroyed: region %p (%d)\n", this, base, size); | |
57 | ||
58 | // remove ourselves from the LL | |
59 | if (first == this) | |
60 | { // special case: we're first | |
61 | first = this->next; | |
62 | return; | |
63 | } | |
64 | ||
65 | // otherwise search the LL for the previous pool | |
66 | MemoryPool* m = first; | |
67 | while (m) | |
68 | { | |
69 | if (m->next == this) | |
70 | { | |
71 | m->next = next; | |
72 | return; | |
73 | } | |
74 | m = m->next; | |
75 | } | |
76 | } | |
77 | ||
78 | void* MemoryPool::alloc(size_t nbytes) | |
79 | { | |
80 | // nbytes = ceil(nbytes / 4) * 4 | |
81 | if (nbytes & 3) | |
82 | nbytes += 4 - (nbytes & 3); | |
83 | ||
84 | // start at the start | |
85 | _poolregion* p = ((_poolregion*) base); | |
86 | ||
87 | // find the allocation size including our metadata | |
88 | uint16_t nsize = nbytes + sizeof(_poolregion); | |
89 | ||
90 | MDEBUG("\tallocate %d bytes from %p\n", nsize, base); | |
91 | ||
92 | // now we walk the list, looking for a sufficiently large free block | |
93 | do { | |
94 | MDEBUG("\t\tchecking %p (%s, %db)\n", p, (p->used?"used":"free"), p->next); | |
95 | if ((p->used == 0) && (p->next >= nsize)) | |
96 | { // we found a free space that's big enough | |
97 | MDEBUG("\t\tFOUND free block at %p (%+d) with %d bytes\n", p, offset(p), p->next); | |
98 | // mark it as used | |
99 | p->used = 1; | |
100 | ||
101 | // if there's free space at the end of this block | |
102 | if (p->next > nsize) | |
103 | { | |
104 | // q = p->next | |
105 | _poolregion* q = (_poolregion*) (((uint8_t*) p) + nsize); | |
106 | ||
107 | MDEBUG("\t\twriting header to %p (%+d) (%d)\n", q, offset(q), p->next - nsize); | |
108 | // write a new block header into q | |
109 | q->used = 0; | |
110 | q->next = p->next - nsize; | |
111 | ||
112 | // set our next to point to it | |
113 | p->next = nsize; | |
114 | ||
3077abb6 | 115 | // sanity check |
56c83a64 | 116 | if (offset(q) >= size) |
3077abb6 MM |
117 | { |
118 | // captain, we have a problem! | |
119 | // this can only happen if something has corrupted our heap, since we should simply fail to find a free block if it's full | |
120 | __debugbreak(); | |
121 | } | |
122 | } | |
123 | ||
3077abb6 MM |
124 | // then return the data region for the block |
125 | return &p->data; | |
126 | } | |
127 | ||
128 | // p = p->next | |
129 | p = (_poolregion*) (((uint8_t*) p) + p->next); | |
130 | ||
131 | // make sure we don't walk off the end | |
56c83a64 | 132 | } while (p <= (_poolregion*) (((uint8_t*)base) + size)); |
3077abb6 MM |
133 | |
134 | // fell off the end of the region! | |
135 | return NULL; | |
136 | } | |
137 | ||
138 | void MemoryPool::dealloc(void* d) | |
139 | { | |
140 | _poolregion* p = (_poolregion*) (((uint8_t*) d) - sizeof(_poolregion)); | |
141 | p->used = 0; | |
142 | ||
143 | MDEBUG("\tdeallocating %p (%+d, %db)\n", p, offset(p), p->next); | |
144 | ||
145 | // combine next block if it's free | |
146 | _poolregion* q = (_poolregion*) (((uint8_t*) p) + p->next); | |
147 | if (q->used == 0) | |
148 | { | |
149 | MDEBUG("\t\tCombining with next free region at %p, new size is %d\n", q, p->next + q->next); | |
150 | ||
3077abb6 | 151 | // sanity check |
56c83a64 | 152 | if (offset(q) > size) |
3077abb6 MM |
153 | { |
154 | // captain, we have a problem! | |
155 | // this can only happen if something has corrupted our heap, since we should simply fail to find a free block if it's full | |
156 | __debugbreak(); | |
157 | } | |
158 | ||
159 | p->next += q->next; | |
160 | } | |
161 | ||
162 | // walk the list to find previous block | |
163 | q = (_poolregion*) base; | |
164 | do { | |
165 | // check if q is the previous block | |
166 | if ((((uint8_t*) q) + q->next) == (uint8_t*) p) { | |
167 | // q is the previous block. | |
168 | if (q->used == 0) | |
169 | { // if q is free | |
170 | MDEBUG("\t\tCombining with previous free region at %p, new size is %d\n", q, p->next + q->next); | |
171 | ||
172 | // combine! | |
173 | q->next += p->next; | |
174 | ||
3077abb6 | 175 | // sanity check |
56c83a64 | 176 | if ((offset(p) + p->next) >= size) |
3077abb6 MM |
177 | { |
178 | // captain, we have a problem! | |
179 | // this can only happen if something has corrupted our heap, since we should simply fail to find a free block if it's full | |
180 | __debugbreak(); | |
181 | } | |
182 | } | |
183 | ||
184 | // we found previous block, return | |
185 | return; | |
186 | } | |
187 | ||
188 | // return if last block | |
56c83a64 | 189 | if (offset(q) + q->next >= size) |
3077abb6 MM |
190 | return; |
191 | ||
192 | // q = q->next | |
193 | q = (_poolregion*) (((uint8_t*) q) + q->next); | |
194 | ||
195 | // if some idiot deallocates our memory region while we're using it, strange things can happen. | |
196 | // avoid an infinite loop in that case, however we'll still leak memory and may corrupt things | |
197 | if (q->next == 0) | |
198 | return; | |
199 | ||
56c83a64 MM |
200 | // make sure we don't walk off the end |
201 | } while (q < (_poolregion*) (((uint8_t*) base) + size)); | |
3077abb6 MM |
202 | } |
203 | ||
1803076a | 204 | void MemoryPool::debug(StreamOutput* str) |
3077abb6 | 205 | { |
3077abb6 | 206 | _poolregion* p = (_poolregion*) base; |
1803076a MM |
207 | uint32_t tot = 0; |
208 | uint32_t free = 0; | |
209 | str->printf("Start: %ub MemoryPool at %p\n", size, p); | |
3077abb6 | 210 | do { |
1803076a MM |
211 | str->printf("\tChunk at %p (%+4d): %s, %lu bytes\n", p, offset(p), (p->used?"used":"free"), p->next); |
212 | tot += p->next; | |
213 | if (p->used == 0) | |
214 | free += p->next; | |
215 | if ((offset(p) + p->next >= size) || (p->next <= sizeof(_poolregion))) | |
3077abb6 | 216 | { |
1803076a | 217 | str->printf("End: total %lub, free: %lub\n", tot, free); |
3077abb6 MM |
218 | return; |
219 | } | |
220 | p = (_poolregion*) (((uint8_t*) p) + p->next); | |
221 | } while (1); | |
3077abb6 MM |
222 | } |
223 | ||
224 | bool MemoryPool::has(void* p) | |
225 | { | |
226 | return ((p >= base) && (p < (void*) (((uint8_t*) base) + size))); | |
227 | } | |
228 | ||
229 | uint32_t MemoryPool::free() | |
230 | { | |
56c83a64 | 231 | uint32_t free = 0; |
3077abb6 MM |
232 | |
233 | _poolregion* p = (_poolregion*) base; | |
234 | ||
235 | do { | |
236 | if (p->used == 0) | |
56c83a64 MM |
237 | free += p->next; |
238 | if (offset(p) + p->next >= size) | |
239 | return free; | |
240 | if (p->next <= sizeof(_poolregion)) | |
3077abb6 MM |
241 | return free; |
242 | p = (_poolregion*) (((uint8_t*) p) + p->next); | |
243 | } while (1); | |
244 | } |