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Revision 1.4 - (view) (download)
| 1 : | Isibaar | 1.2 | #include <stdlib.h> |
| 2 : | #include <stdio.h> | ||
| 3 : | #include "mem_align.h" | ||
| 4 : | |||
| 5 : | void *xvid_malloc(size_t size, uint8_t alignment) | ||
| 6 : | { | ||
| 7 : | edgomez | 1.3 | uint8_t *mem_ptr; |
| 8 : | Isibaar | 1.2 | |
| 9 : | edgomez | 1.4 | if(!alignment) |
| 10 : | edgomez | 1.3 | { |
| 11 : | edgomez | 1.4 | |
| 12 : | /* We have not to satisfy any alignment */ | ||
| 13 : | if((mem_ptr = (uint8_t *) malloc(size + 1)) != NULL) | ||
| 14 : | { | ||
| 15 : | |||
| 16 : | /* Store (mem_ptr - "real allocated memory") in *(mem_ptr-1) */ | ||
| 17 : | edgomez | 1.3 | *mem_ptr = 0; |
| 18 : | edgomez | 1.4 | |
| 19 : | /* Return the mem_ptr pointer */ | ||
| 20 : | edgomez | 1.3 | return (void *) mem_ptr++; |
| 21 : | edgomez | 1.4 | |
| 22 : | edgomez | 1.3 | } |
| 23 : | edgomez | 1.4 | |
| 24 : | edgomez | 1.3 | } |
| 25 : | else | ||
| 26 : | { | ||
| 27 : | uint8_t *tmp; | ||
| 28 : | Isibaar | 1.2 | |
| 29 : | edgomez | 1.4 | /* |
| 30 : | * Allocate the required size memory + alignment so we | ||
| 31 : | * can realign the data if necessary | ||
| 32 : | */ | ||
| 33 : | |||
| 34 : | if((tmp = (uint8_t *) malloc(size + alignment)) != NULL) | ||
| 35 : | { | ||
| 36 : | |||
| 37 : | /* Align the tmp pointer */ | ||
| 38 : | edgomez | 1.3 | mem_ptr = (uint8_t *)((uint32_t)(tmp + alignment - 1)&(~(uint32_t)(alignment - 1))); |
| 39 : | edgomez | 1.4 | |
| 40 : | /* | ||
| 41 : | * Special case where malloc have already satisfied the alignment | ||
| 42 : | * We must add alignment to mem_ptr because we must store | ||
| 43 : | * (mem_ptr - tmp) in *(mem_ptr-1) | ||
| 44 : | * If we do not add alignment to mem_ptr then *(mem_ptr-1) points | ||
| 45 : | * to a forbidden memory space | ||
| 46 : | */ | ||
| 47 : | if(mem_ptr == tmp) mem_ptr += alignment; | ||
| 48 : | |||
| 49 : | /* | ||
| 50 : | * (mem_ptr - tmp) is stored in *(mem_ptr-1) so we are able to retrieve | ||
| 51 : | * the real malloc block allocated and free it in xvid_free | ||
| 52 : | */ | ||
| 53 : | edgomez | 1.3 | *(mem_ptr - 1) = (uint8_t)(mem_ptr - tmp); |
| 54 : | edgomez | 1.4 | |
| 55 : | /* Return the aligned pointer */ | ||
| 56 : | edgomez | 1.3 | return (void *) mem_ptr; |
| 57 : | edgomez | 1.4 | |
| 58 : | edgomez | 1.3 | } |
| 59 : | } | ||
| 60 : | |||
| 61 : | return NULL; | ||
| 62 : | Isibaar | 1.2 | |
| 63 : | } | ||
| 64 : | |||
| 65 : | void xvid_free(void *mem_ptr) | ||
| 66 : | { | ||
| 67 : | |||
| 68 : | edgomez | 1.4 | /* *(mem_ptr - 1) give us the offset to the real malloc block */ |
| 69 : | free((uint8_t*)mem_ptr - *((uint8_t*)mem_ptr - 1)); | ||
| 70 : | Isibaar | 1.2 | |
| 71 : | } |
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