3 * - By John Hodge (thePowersGang)
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6 * - Dynamic Memory (malloc/free)
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8 #include <acess/sys.h>
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14 # define DEBUGS(s...) _SysDebug(s)
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16 # define DEBUGS(s...) do{}while(0)
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19 // === Constants ===
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20 #define MAGIC 0xACE55051 //AcessOS1
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21 #define MAGIC_FREE (~MAGIC)
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22 #define BLOCK_SIZE 16 //Minimum
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23 #define HEAP_INIT_SIZE 0x10000
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24 #define DEBUG_HEAP 1
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26 typedef unsigned int Uint;
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45 static inline heap_head *NEXT_HEAD(heap_head *ptr)
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47 return (void*)((char*)ptr + ptr->size);
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49 static inline heap_foot *THIS_FOOT(heap_head *ptr)
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51 return (void*)((char*)ptr + ptr->size - sizeof(heap_foot));
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53 static inline heap_foot *PREV_FOOT(heap_head *ptr)
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55 return (void*)((char*)ptr - sizeof(heap_foot));
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57 static inline size_t CALC_BLOCK_SIZE(size_t bytes)
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60 ret = bytes + sizeof(heap_head) + sizeof(heap_foot) + BLOCK_SIZE - 1;
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61 ret = (ret/BLOCK_SIZE)*BLOCK_SIZE; //Round up to block size
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65 // === LOCAL VARIABLES ===
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66 static heap_head *_heap_start = NULL;
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67 static heap_head *_heap_end = NULL;
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68 static const heap_head _heap_zero_allocation;
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70 // === PROTOTYPES ===
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71 EXPORT void *malloc(size_t bytes);
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72 void *_malloc(size_t bytes, void *owner);
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73 EXPORT void *calloc(size_t bytes, size_t count);
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74 EXPORT void free(void *mem);
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75 EXPORT void *realloc(void *mem, size_t bytes);
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76 EXPORT void *sbrk(int increment);
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77 LOCAL void *extendHeap(int bytes);
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78 static void *FindHeapBase();
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79 LOCAL uint brk(uintptr_t newpos);
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80 EXPORT int Heap_Validate(int bDump);
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85 \fn EXPORT void *malloc(size_t bytes)
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86 \brief Allocates memory from the heap space
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87 \param bytes Integer - Size of buffer to return
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88 \return Pointer to buffer
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90 EXPORT void *malloc(size_t bytes)
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92 return _malloc(bytes, __builtin_return_address(0));
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95 void *_malloc(size_t bytes, void *owner)
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97 size_t closestMatch = 0;
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98 void *bestMatchAddr = 0;
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101 if(_heap_start == NULL)
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103 _heap_start = sbrk(0);
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104 _heap_end = _heap_start;
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105 extendHeap(HEAP_INIT_SIZE);
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108 // Zero bytes, return a random area (in .rodata)
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110 return (void*)_heap_zero_allocation.data;
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112 // Calculate the required block size
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113 size_t bestSize = CALC_BLOCK_SIZE(bytes);
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115 heap_head *curBlock;
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116 for(curBlock = _heap_start; curBlock < _heap_end; curBlock = NEXT_HEAD(curBlock))
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118 //_SysDebug(" malloc: curBlock = 0x%x, curBlock->magic = 0x%x\n", curBlock, curBlock->magic);
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119 if(curBlock->magic == MAGIC_FREE)
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121 // Perfect match, nice
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122 if(curBlock->size == bestSize)
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124 // Check if this is a tighter match than the last free block
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125 if(bestSize < curBlock->size && (curBlock->size < closestMatch || closestMatch == 0)) {
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126 closestMatch = curBlock->size;
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127 bestMatchAddr = curBlock;
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130 else if(curBlock->magic != MAGIC)
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134 _SysDebug("malloc: Corrupt Heap when called by %p\n", owner);
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140 if(curBlock < _heap_start) {
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142 _SysDebug("malloc: Heap underrun for some reason\n");
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147 //Found a perfect match
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148 if(curBlock < _heap_end) {
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149 curBlock->magic = MAGIC;
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150 curBlock->RealSize = bytes;
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151 curBlock->Caller = owner;
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152 return curBlock->data;
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155 //Out of Heap Space
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156 if(!closestMatch) {
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157 curBlock = extendHeap(bestSize); //Allocate more
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158 if(curBlock == NULL) {
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159 _SysDebug("malloc: Out of Heap Space\n");
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162 curBlock->magic = MAGIC;
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163 curBlock->RealSize = bytes;
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164 curBlock->Caller = owner;
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165 DEBUGS("malloc(0x%x) = %p (extend) 0x%x", bytes, curBlock->data, bestSize);
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166 return curBlock->data;
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169 heap_head *besthead = (void*)bestMatchAddr;
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171 // Do we need to split this block?
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172 if(closestMatch - bestSize > BLOCK_SIZE) {
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175 // Block we're going to return
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176 curBlock = (heap_head*)bestMatchAddr;
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177 curBlock->magic = MAGIC;
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178 curBlock->size = bestSize;
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179 foot = THIS_FOOT(curBlock);
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180 foot->header = curBlock;
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181 foot->magic = MAGIC;
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183 // Remaining parts of the block
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184 curBlock = (heap_head*)(bestMatchAddr + bestSize);
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185 curBlock->magic = MAGIC_FREE;
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186 curBlock->size = closestMatch - bestSize;
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187 foot = THIS_FOOT(curBlock);
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188 foot->header = curBlock;
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190 // Mark return as used
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191 DEBUGS("malloc(0x%x) = %p (split) 0x%x", bytes, besthead->data, bestSize);
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194 // No need to split
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195 DEBUGS("malloc(0x%x) = %p (reuse) 0x%x", bytes, besthead->data, besthead->size);
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198 besthead->magic = MAGIC;
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199 besthead->RealSize = bytes;
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200 besthead->Caller = owner;
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201 return besthead->data;
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205 * \fn EXPORT void *calloc(size_t bytes, size_t count)
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206 * \brief Allocate and zero a block of memory
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207 * \param __nmemb Number of memeber elements
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208 * \param __size Size of one element
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210 EXPORT void *calloc(size_t __nmemb, size_t __size)
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212 void *ret = _malloc(__size*__nmemb, __builtin_return_address(0));
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213 if(!ret) return NULL;
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214 memset(ret, 0, __size*__nmemb);
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219 \fn EXPORT void free(void *mem)
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220 \brief Free previously allocated memory
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221 \param mem Pointer - Memory to free
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223 EXPORT void free(void *mem)
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225 heap_head *head = (heap_head*)mem - 1;
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227 // Free of NULL or the zero allocation does nothing
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228 if(!mem || mem == _heap_zero_allocation.data)
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231 // Sanity check the head address
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232 if(head->magic != MAGIC) {
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233 if( head->magic != MAGIC_FREE ) {
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234 _SysDebug("Double free of %p", mem);
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239 _SysDebug("Free of invalid pointer %p", mem);
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246 head->magic = MAGIC_FREE;
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247 DEBUGS("free(%p) : 0x%x bytes", mem, head->size);
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250 if( NEXT_HEAD(head) < _heap_end )
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252 heap_head *nextHead = NEXT_HEAD(head);
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253 // Is the next block free?
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254 if(nextHead->magic == MAGIC_FREE)
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256 head->size += nextHead->size; // Amalgamate
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257 THIS_FOOT(head)->header = head;
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258 nextHead->magic = 0; //For Security
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263 if( head > _heap_start )
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265 heap_foot *prevFoot = PREV_FOOT(head);
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266 if( prevFoot->magic != MAGIC )
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272 heap_head *prevHead = prevFoot->header;
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273 if(prevHead->magic == MAGIC_FREE)
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276 prevHead->size += head->size;
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277 THIS_FOOT(prevHead)->header = prevHead;
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280 prevFoot->magic = 0;
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281 prevFoot->header = NULL;
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287 \fn EXPORT void *realloc(void *oldPos, size_t bytes)
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288 \brief Reallocate a block of memory
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289 \param bytes Integer - Size of new buffer
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290 \param oldPos Pointer - Old Buffer
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291 \return Pointer to new buffer
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293 EXPORT void *realloc(void *oldPos, size_t bytes)
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295 if(oldPos == NULL || oldPos == _heap_zero_allocation.data) {
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296 return _malloc(bytes, __builtin_return_address(0));
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299 size_t reqd_size = CALC_BLOCK_SIZE(bytes);
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301 // Check for free space within the block
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302 // - oldPos points to just after the header, so -1 gives the header
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303 heap_head *head = (heap_head*)oldPos - 1;
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304 if( head->size >= reqd_size ) {
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305 head->RealSize = bytes;
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309 // Check for free space after the block
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310 heap_head *nexthead = NEXT_HEAD(head);
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311 if( nexthead && nexthead->magic == MAGIC_FREE && head->size + nexthead->size >= reqd_size )
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313 // Split next block
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314 if( head->size + nexthead->size > reqd_size )
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316 size_t newblocksize = nexthead->size - (reqd_size - head->size);
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317 head->size = reqd_size;
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319 nexthead = NEXT_HEAD(head);
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320 nexthead->size = newblocksize;
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321 nexthead->magic = MAGIC_FREE;
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322 THIS_FOOT(nexthead)->header = nexthead;
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326 head->size = reqd_size;
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328 THIS_FOOT(head)->magic = MAGIC;
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329 THIS_FOOT(head)->header = head;
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330 head->RealSize = bytes;
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334 // TODO: Should I check for free before too? What about before AND after?
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336 // Allocate new memory
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337 void *ret = _malloc(bytes, __builtin_return_address(0));
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342 size_t copy_size = head->size-sizeof(heap_head)-sizeof(heap_foot);
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343 if( copy_size > bytes )
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345 memcpy(ret, oldPos, bytes);
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353 * \fn LOCAL void *extendHeap(int bytes)
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354 * \brief Create a new block at the end of the heap area
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355 * \param bytes Integer - Size reqired
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356 * \return Pointer to last free block
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359 LOCAL void *extendHeap(int bytes)
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361 heap_head *head = _heap_end;
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364 //Expand Memory Space (Use foot as a temp pointer)
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365 foot = sbrk(bytes);
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366 if(foot == (void*)-1)
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371 head->magic = MAGIC_FREE; //Unallocated
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372 head->size = bytes;
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374 foot = THIS_FOOT(head);
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375 foot->header = head;
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376 foot->magic = MAGIC;
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378 //Combine with previous block if nessasary
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379 if(_heap_end != _heap_start && ((heap_foot*)((uintptr_t)_heap_end-sizeof(heap_foot)))->magic == MAGIC) {
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380 heap_head *tmpHead = ((heap_foot*)((uintptr_t)_heap_end-sizeof(heap_foot)))->header;
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381 if(tmpHead->magic == MAGIC_FREE) {
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382 tmpHead->size += bytes;
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383 foot->header = tmpHead;
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388 _heap_end = (void*) ((uintptr_t)foot+sizeof(heap_foot));
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393 \fn EXPORT void *sbrk(int increment)
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394 \brief Increases the program's memory space
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395 \param count Integer - Size of heap increase
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396 \return Pointer to start of new region
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398 EXPORT void *sbrk(int increment)
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400 static uintptr_t oldEnd = 0;
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401 static uintptr_t curEnd = 0;
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403 //_SysDebug("sbrk: (increment=%i)", increment);
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406 oldEnd = curEnd = (uintptr_t)FindHeapBase();
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407 //_SysAllocate(curEnd); // Allocate the first page
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410 //_SysDebug(" sbrk: oldEnd = 0x%x", oldEnd);
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411 if (increment == 0) return (void *) curEnd;
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416 if( (curEnd & 0xFFF) && (curEnd & 0xFFF) + increment < 0x1000 )
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418 //if( curEnd & 0xFFF == 0 )
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420 // if( !_SysAllocate(curEnd) )
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422 // _SysDebug("sbrk - Error allocating memory");
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423 // return (void*)-1;
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426 curEnd += increment;
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427 //_SysDebug("sbrk: RETURN %p (single page, no alloc)", (void *) oldEnd);
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428 return (void *)oldEnd;
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431 increment -= curEnd & 0xFFF;
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432 curEnd += 0xFFF; curEnd &= ~0xFFF;
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433 while( increment > 0 )
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435 if( !_SysAllocate(curEnd) )
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438 _SysDebug("sbrk - Error allocating memory");
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441 increment -= 0x1000;
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445 //_SysDebug("sbrk: RETURN %p", (void *) oldEnd);
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446 return (void *) oldEnd;
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450 * \fn EXPORT int IsHeap(void *ptr)
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452 EXPORT int IsHeap(void *ptr)
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454 if( ptr == _heap_zero_allocation.data )
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460 if( (uintptr_t)ptr < (uintptr_t)_heap_start ) return 0;
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461 if( (uintptr_t)ptr > (uintptr_t)_heap_end ) return 0;
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464 head = (void*)((Uint)ptr - 4);
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465 if( head->magic != MAGIC ) return 0;
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466 foot = (void*)( (Uint)ptr + head->size - sizeof(heap_foot) );
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467 if( foot->magic != MAGIC ) return 0;
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472 // === STATIC FUNCTIONS ===
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474 * Does the job of brk(0)
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476 static void *FindHeapBase()
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479 #define MAX 0xC0000000 // Address
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480 #define THRESHOLD 512 // Pages
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485 // Scan address space
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491 tmp = _SysGetPhys(addr);
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496 if(stretch > THRESHOLD)
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498 return (void*)( addr - stretch*0x1000 );
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501 //__asm__ __volatile__ (
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502 // "push %%ebx;mov %%edx,%%ebx;int $0xAC;pop %%ebx"
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503 // ::"a"(256),"d"("%x"),"c"(addr));
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508 return (void*)0x00900000;
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512 LOCAL uint brk(uintptr_t newpos)
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514 static uintptr_t curpos;
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519 _SysDebug("brk: (newpos=0x%x)", newpos);
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521 // Find initial position
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522 if(curpos == 0) curpos = (uintptr_t)FindHeapBase();
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524 // Get Current Position
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525 if(newpos == 0) return curpos;
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527 if(newpos < curpos) return newpos;
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529 delta = newpos - curpos;
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530 _SysDebug(" brk: delta = 0x%x", delta);
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532 // Do we need to add pages
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533 if(curpos & 0xFFF && (curpos & 0xFFF) + delta < 0x1000)
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534 return curpos += delta;
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536 // Page align current position
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537 if(curpos & 0xFFF) delta -= 0x1000 - (curpos & 0xFFF);
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538 curpos = (curpos + 0xFFF) & ~0xFFF;
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541 pages = (delta + 0xFFF) >> 12;
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544 _SysAllocate(curpos);
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549 // Bring the current position to exactly what we want
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550 curpos -= ((delta + 0xFFF) & ~0xFFF) - delta;
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552 return ret; // Return old curpos
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555 int Heap_Validate(int bDump)
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558 heap_head *cur = _heap_start;
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559 while( cur < (heap_head*)_heap_end && rv == 0 )
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561 if( cur->magic == MAGIC ) {
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563 _SysDebug("Used block %p[0x%x] - ptr=%p,Owner=%p,Size=0x%x",
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564 cur, cur->size, cur->data,
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565 cur->Caller, cur->RealSize
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569 else if( cur->magic == MAGIC_FREE ) {
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571 _SysDebug("Free block %p[0x%x]", cur, cur->size, cur->data);
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575 _SysDebug("Block %p bad magic (0x%x)", cur, cur->magic);
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579 heap_foot *foot = THIS_FOOT(cur);
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580 if( foot->magic != MAGIC ) {
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581 _SysDebug("- %p: Foot magic clobbered (0x%x!=0x%x)", cur, foot->magic, MAGIC);
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584 if( foot->header != cur ) {
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585 _SysDebug("- %p: Head pointer clobbered (%p)", cur, foot->header);
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589 if( rv && !bDump ) {
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590 _SysDebug("%s block %p[0x%x] - ptr=%p,Owner=%p,Size=0x%x",
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591 (cur->magic == MAGIC ? "Used":"Free"),
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592 cur, cur->size, cur->data,
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593 cur->Caller, cur->RealSize
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597 cur = NEXT_HEAD(cur);
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599 if( rv && !bDump ) {
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600 _SysDebug("- Caller: %p", __builtin_return_address(0));
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