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#include <stdlib.h> |
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#include <stdio.h> |
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#include "mem_align.h" |
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|
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void *xvid_malloc(size_t size, uint8_t alignment) |
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{ |
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uint8_t *mem_ptr; |
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|
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if(!alignment) |
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{ |
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|
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/* We have not to satisfy any alignment */ |
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if((mem_ptr = (uint8_t *) malloc(size + 1)) != NULL) |
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{ |
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|
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/* Store (mem_ptr - "real allocated memory") in *(mem_ptr-1) */ |
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*mem_ptr = 0; |
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|
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/* Return the mem_ptr pointer */ |
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return (void *) mem_ptr++; |
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|
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} |
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|
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} |
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else |
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{ |
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uint8_t *tmp; |
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|
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/* |
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* Allocate the required size memory + alignment so we |
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* can realign the data if necessary |
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*/ |
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|
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if((tmp = (uint8_t *) malloc(size + alignment)) != NULL) |
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{ |
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|
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/* Align the tmp pointer */ |
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mem_ptr = (uint8_t *)((uint32_t)(tmp + alignment - 1)&(~(uint32_t)(alignment - 1))); |
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|
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/* |
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* Special case where malloc have already satisfied the alignment |
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* We must add alignment to mem_ptr because we must store |
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* (mem_ptr - tmp) in *(mem_ptr-1) |
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* If we do not add alignment to mem_ptr then *(mem_ptr-1) points |
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* to a forbidden memory space |
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*/ |
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if(mem_ptr == tmp) mem_ptr += alignment; |
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|
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/* |
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* (mem_ptr - tmp) is stored in *(mem_ptr-1) so we are able to retrieve |
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* the real malloc block allocated and free it in xvid_free |
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*/ |
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*(mem_ptr - 1) = (uint8_t)(mem_ptr - tmp); |
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|
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/* Return the aligned pointer */ |
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return (void *) mem_ptr; |
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|
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} |
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} |
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|
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return NULL; |
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|
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} |
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|
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void xvid_free(void *mem_ptr) |
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{ |
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|
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/* *(mem_ptr - 1) give us the offset to the real malloc block */ |
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if(mem_ptr) |
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free((uint8_t*)mem_ptr - *((uint8_t*)mem_ptr - 1)); |
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|
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} |
