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Revision 1.15.2.3 - (view) (download)
| 1 : | edgomez | 1.7 | /***************************************************************************** |
| 2 : | * | ||
| 3 : | * XVID MPEG-4 VIDEO CODEC | ||
| 4 : | edgomez | 1.15.2.2 | * - Aligned Memory Allocator - |
| 5 : | edgomez | 1.7 | * |
| 6 : | edgomez | 1.15.2.2 | * Copyright(C) 2002-2003 Edouard Gomez <ed.gomez@free.fr> |
| 7 : | edgomez | 1.15 | * |
| 8 : | * This program is free software ; you can redistribute it and/or modify | ||
| 9 : | * it under the terms of the GNU General Public License as published by | ||
| 10 : | * the Free Software Foundation ; either version 2 of the License, or | ||
| 11 : | edgomez | 1.7 | * (at your option) any later version. |
| 12 : | * | ||
| 13 : | * This program is distributed in the hope that it will be useful, | ||
| 14 : | edgomez | 1.15 | * but WITHOUT ANY WARRANTY ; without even the implied warranty of |
| 15 : | edgomez | 1.7 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 : | * GNU General Public License for more details. | ||
| 17 : | * | ||
| 18 : | * You should have received a copy of the GNU General Public License | ||
| 19 : | edgomez | 1.15 | * along with this program ; if not, write to the Free Software |
| 20 : | edgomez | 1.7 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 21 : | * | ||
| 22 : | edgomez | 1.15.2.2 | * $Id$ |
| 23 : | edgomez | 1.7 | * |
| 24 : | ****************************************************************************/ | ||
| 25 : | edgomez | 1.15 | |
| 26 : | Isibaar | 1.2 | #include <stdlib.h> |
| 27 : | #include <stdio.h> | ||
| 28 : | #include "mem_align.h" | ||
| 29 : | |||
| 30 : | edgomez | 1.7 | /***************************************************************************** |
| 31 : | * xvid_malloc | ||
| 32 : | * | ||
| 33 : | * This function allocates 'size' bytes (usable by the user) on the heap and | ||
| 34 : | * takes care of the requested 'alignment'. | ||
| 35 : | * In order to align the allocated memory block, the xvid_malloc allocates | ||
| 36 : | * 'size' bytes + 'alignment' bytes. So try to keep alignment very small | ||
| 37 : | * when allocating small pieces of memory. | ||
| 38 : | * | ||
| 39 : | * NB : a block allocated by xvid_malloc _must_ be freed with xvid_free | ||
| 40 : | * (the libc free will return an error) | ||
| 41 : | * | ||
| 42 : | * Returned value : - NULL on error | ||
| 43 : | * - Pointer to the allocated aligned block | ||
| 44 : | * | ||
| 45 : | ****************************************************************************/ | ||
| 46 : | |||
| 47 : | edgomez | 1.6 | void * |
| 48 : | xvid_malloc(size_t size, | ||
| 49 : | uint8_t alignment) | ||
| 50 : | Isibaar | 1.2 | { |
| 51 : | edgomez | 1.3 | uint8_t *mem_ptr; |
| 52 : | edgomez | 1.6 | |
| 53 : | if (!alignment) { | ||
| 54 : | edgomez | 1.4 | |
| 55 : | /* We have not to satisfy any alignment */ | ||
| 56 : | edgomez | 1.6 | if ((mem_ptr = (uint8_t *) malloc(size + 1)) != NULL) { |
| 57 : | edgomez | 1.4 | |
| 58 : | /* Store (mem_ptr - "real allocated memory") in *(mem_ptr-1) */ | ||
| 59 : | edgomez | 1.15.2.3 | *mem_ptr = (uint8_t)1; |
| 60 : | edgomez | 1.4 | |
| 61 : | /* Return the mem_ptr pointer */ | ||
| 62 : | edgomez | 1.15.2.3 | return ((void *)(mem_ptr+1)); |
| 63 : | edgomez | 1.3 | } |
| 64 : | edgomez | 1.6 | } else { |
| 65 : | edgomez | 1.3 | uint8_t *tmp; |
| 66 : | edgomez | 1.6 | |
| 67 : | edgomez | 1.15.2.3 | /* Allocate the required size memory + alignment so we |
| 68 : | * can realign the data if necessary */ | ||
| 69 : | edgomez | 1.6 | if ((tmp = (uint8_t *) malloc(size + alignment)) != NULL) { |
| 70 : | edgomez | 1.4 | |
| 71 : | /* Align the tmp pointer */ | ||
| 72 : | edgomez | 1.6 | mem_ptr = |
| 73 : | Isibaar | 1.8 | (uint8_t *) ((ptr_t) (tmp + alignment - 1) & |
| 74 : | (~(ptr_t) (alignment - 1))); | ||
| 75 : | edgomez | 1.4 | |
| 76 : | edgomez | 1.15.2.3 | /* Special case where malloc have already satisfied the alignment |
| 77 : | edgomez | 1.4 | * We must add alignment to mem_ptr because we must store |
| 78 : | * (mem_ptr - tmp) in *(mem_ptr-1) | ||
| 79 : | * If we do not add alignment to mem_ptr then *(mem_ptr-1) points | ||
| 80 : | edgomez | 1.15.2.3 | * to a forbidden memory space */ |
| 81 : | edgomez | 1.6 | if (mem_ptr == tmp) |
| 82 : | mem_ptr += alignment; | ||
| 83 : | edgomez | 1.4 | |
| 84 : | edgomez | 1.15.2.3 | /* (mem_ptr - tmp) is stored in *(mem_ptr-1) so we are able to retrieve |
| 85 : | * the real malloc block allocated and free it in xvid_free */ | ||
| 86 : | edgomez | 1.6 | *(mem_ptr - 1) = (uint8_t) (mem_ptr - tmp); |
| 87 : | edgomez | 1.4 | |
| 88 : | /* Return the aligned pointer */ | ||
| 89 : | edgomez | 1.15.2.3 | return ((void *)mem_ptr); |
| 90 : | edgomez | 1.3 | } |
| 91 : | } | ||
| 92 : | |||
| 93 : | edgomez | 1.15.2.3 | return(NULL); |
| 94 : | Isibaar | 1.2 | } |
| 95 : | edgomez | 1.7 | |
| 96 : | /***************************************************************************** | ||
| 97 : | * xvid_free | ||
| 98 : | * | ||
| 99 : | * Free a previously 'xvid_malloc' allocated block. Does not free NULL | ||
| 100 : | * references. | ||
| 101 : | * | ||
| 102 : | * Returned value : None. | ||
| 103 : | * | ||
| 104 : | ****************************************************************************/ | ||
| 105 : | Isibaar | 1.2 | |
| 106 : | edgomez | 1.6 | void |
| 107 : | xvid_free(void *mem_ptr) | ||
| 108 : | Isibaar | 1.2 | { |
| 109 : | |||
| 110 : | edgomez | 1.15.2.3 | uint8_t *ptr; |
| 111 : | |||
| 112 : | if (mem_ptr == NULL) | ||
| 113 : | return; | ||
| 114 : | |||
| 115 : | /* Aligned pointer */ | ||
| 116 : | ptr = mem_ptr; | ||
| 117 : | |||
| 118 : | /* *(ptr - 1) holds the offset to the real allocated block | ||
| 119 : | * we sub that offset os we free the real pointer */ | ||
| 120 : | ptr -= *(ptr - 1); | ||
| 121 : | Isibaar | 1.2 | |
| 122 : | edgomez | 1.15.2.3 | /* Free the memory */ |
| 123 : | free(ptr); | ||
| 124 : | Isibaar | 1.2 | } |
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