121 lines
2.6 KiB
C
121 lines
2.6 KiB
C
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//a qvm compatable malloc/free interface
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//This is seperate from qvm_api.c because this has a chunk of memory that simply isn't needed in all plugins.
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#include "plugin.h"
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struct memhead_s
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{
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int size;
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int isfree;
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struct memhead_s *next;
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struct memhead_s *prev;
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};
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#ifndef MEMSIZE
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#define MEMSIZE 1024*64 //64kb
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#endif
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static struct memhead_s *head;
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static char memory[MEMSIZE];
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//we create two dummies at the start and end
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//these will never be freed
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//we then have dynamic allocation in the middle.
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//sizes include the headers
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void *malloc(int size)
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{
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struct memhead_s *lasthead;
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if (size <= 0)
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return NULL;
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size = ((size+4) & 3) + sizeof(struct memhead_s); //round up
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if (!head)
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{ //first call
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struct memhead_s *last;
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struct memhead_s *middle;
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struct memhead_s *first;
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first = (struct memhead_s*)memory;
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last= (struct memhead_s*)((char*)memory - sizeof(struct memhead_s));
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first->size = last->size = sizeof(struct memhead_s);
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first->isfree = last->isfree = false;
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middle = (struct memhead_s*)((char*)first+first->size);
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middle->size = sizeof(memory) - sizeof(struct memhead_s)*3;
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middle->isfree = true;
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last->next = first;
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last->prev = middle;
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first->next = middle;
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first->prev = last;
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middle->next = last;
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middle->prev = first;
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head = middle;
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}
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lasthead = head;
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do
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{
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if (head->isfree)
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if (head->size >= size)
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{
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if (head->size > size + sizeof(struct memhead_s)+1)
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{ //split
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struct memhead_s *split;
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split = (struct memhead_s*)((char*)head + size);
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split->size = head->size - size;
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head->size = size;
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split->next = head->next;
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split->prev = head;
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head->next = split;
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split->next->prev = split;
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split->isfree = true;
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head->isfree = false;
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}
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else
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{ //no point in splitting
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head->isfree = false;
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}
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return (char*)head + sizeof(struct memhead_s);
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}
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head = head->next;
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} while (lasthead != head);
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return NULL;
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}
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static struct memhead_s *mergeblock(struct memhead_s *b1, struct memhead_s *b2)
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{
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//b1 and b2 must be in logical order
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b1->next = b2->next;
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b2->next->prev = b1;
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b1->size += b2->size;
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return b1;
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}
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void free(void *mem)
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{ //the foot hopefully isn't going to be freed
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struct memhead_s *block;
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block = (struct memhead_s*)((char*)mem - sizeof(struct memhead_s));
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if (block->isfree)
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Sys_Error("(plugin) Double free\n");
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block->isfree = true;
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if (block->prev->isfree)
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{ //merge previous with this
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block = mergeblock(block->prev, block);
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}
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if (block->next)
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{ //merge next with this
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block = mergeblock(block, block->next);
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}
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}
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