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103 lines
2 KiB
C
103 lines
2 KiB
C
/* copyright (c) 2007 magnus auvinen, see licence.txt for more info */
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#include "e_system.h"
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typedef struct CHUNK_t
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{
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char *memory;
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char *current;
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char *end;
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struct CHUNK_t *next;
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} CHUNK;
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typedef struct
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{
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CHUNK *current;
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} HEAP;
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/* how large each chunk should be */
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static const int chunksize = 1024*64;
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/* allocates a new chunk to be used */
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static CHUNK *memheap_newchunk()
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{
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CHUNK *chunk;
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char *mem;
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/* allocate memory */
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mem = (char*)mem_alloc(sizeof(CHUNK)+chunksize, 1);
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if(!mem)
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return 0x0;
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/* the chunk structure is located in the begining of the chunk */
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/* init it and return the chunk */
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chunk = (CHUNK*)mem;
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chunk->memory = (char*)(chunk+1);
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chunk->current = chunk->memory;
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chunk->end = chunk->memory + chunksize;
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chunk->next = (CHUNK *)0x0;
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return chunk;
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}
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/******************/
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static void *memheap_allocate_from_chunk(CHUNK *chunk, unsigned int size)
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{
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char *mem;
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/* check if we need can fit the allocation */
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if(chunk->current + size > chunk->end)
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return (void*)0x0;
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/* get memory and move the pointer forward */
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mem = chunk->current;
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chunk->current += size;
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return mem;
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}
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/* creates a heap */
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HEAP *memheap_create()
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{
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CHUNK *chunk;
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HEAP *heap;
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/* allocate a chunk and allocate the heap structure on that chunk */
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chunk = memheap_newchunk();
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heap = (HEAP *)memheap_allocate_from_chunk(chunk, sizeof(HEAP));
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heap->current = chunk;
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return heap;
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}
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/* destroys the heap */
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void memheap_destroy(HEAP *heap)
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{
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CHUNK *chunk = heap->current;
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CHUNK *next;
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while(chunk)
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{
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next = chunk->next;
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mem_free(chunk);
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chunk = next;
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}
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}
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/* */
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void *memheap_allocate(HEAP *heap, unsigned int size)
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{
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char *mem;
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/* try to allocate from current chunk */
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mem = (char *)memheap_allocate_from_chunk(heap->current, size);
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if(!mem)
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{
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/* allocate new chunk and add it to the heap */
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CHUNK *chunk = memheap_newchunk();
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chunk->next = heap->current;
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heap->current = chunk;
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/* try to allocate again */
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mem = (char *)memheap_allocate_from_chunk(heap->current, size);
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}
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return mem;
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}
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