1 |
|
/***************************************************************************** |
2 |
|
* |
3 |
|
* XVID MPEG-4 VIDEO CODEC |
4 |
|
* - Aligned Memory Allocator - |
5 |
|
* |
6 |
|
* Copyright(C) 2002-2003 Edouard Gomez <ed.gomez@free.fr> |
7 |
|
* |
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 |
|
* (at your option) any later version. |
12 |
|
* |
13 |
|
* This program is distributed in the hope that it will be useful, |
14 |
|
* but WITHOUT ANY WARRANTY ; without even the implied warranty of |
15 |
|
* 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 |
|
* along with this program ; if not, write to the Free Software |
20 |
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
21 |
|
* |
22 |
|
* $Id$ |
23 |
|
* |
24 |
|
****************************************************************************/ |
25 |
|
|
26 |
#include <stdlib.h> |
#include <stdlib.h> |
27 |
#include <stdio.h> |
#include <stdio.h> |
28 |
#include "mem_align.h" |
#include "mem_align.h" |
29 |
|
|
30 |
|
/***************************************************************************** |
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 |
void * |
void * |
48 |
xvid_malloc(size_t size, |
xvid_malloc(size_t size, |
49 |
uint8_t alignment) |
uint8_t alignment) |
56 |
if ((mem_ptr = (uint8_t *) malloc(size + 1)) != NULL) { |
if ((mem_ptr = (uint8_t *) malloc(size + 1)) != NULL) { |
57 |
|
|
58 |
/* Store (mem_ptr - "real allocated memory") in *(mem_ptr-1) */ |
/* Store (mem_ptr - "real allocated memory") in *(mem_ptr-1) */ |
59 |
*mem_ptr = 0; |
*mem_ptr = (uint8_t)1; |
60 |
|
|
61 |
/* Return the mem_ptr pointer */ |
/* Return the mem_ptr pointer */ |
62 |
return (void *) mem_ptr++; |
return ((void *)(mem_ptr+1)); |
|
|
|
63 |
} |
} |
|
|
|
64 |
} else { |
} else { |
65 |
uint8_t *tmp; |
uint8_t *tmp; |
66 |
|
|
67 |
/* |
/* Allocate the required size memory + alignment so we |
68 |
* Allocate the required size memory + alignment so we |
* can realign the data if necessary */ |
|
* can realign the data if necessary |
|
|
*/ |
|
|
|
|
69 |
if ((tmp = (uint8_t *) malloc(size + alignment)) != NULL) { |
if ((tmp = (uint8_t *) malloc(size + alignment)) != NULL) { |
70 |
|
|
71 |
/* Align the tmp pointer */ |
/* Align the tmp pointer */ |
72 |
mem_ptr = |
mem_ptr = |
73 |
(uint8_t *) ((uint32_t) (tmp + alignment - 1) & |
(uint8_t *) ((ptr_t) (tmp + alignment - 1) & |
74 |
(~(uint32_t) (alignment - 1))); |
(~(ptr_t) (alignment - 1))); |
75 |
|
|
76 |
/* |
/* Special case where malloc have already satisfied the alignment |
|
* Special case where malloc have already satisfied the alignment |
|
77 |
* We must add alignment to mem_ptr because we must store |
* We must add alignment to mem_ptr because we must store |
78 |
* (mem_ptr - tmp) in *(mem_ptr-1) |
* (mem_ptr - tmp) in *(mem_ptr-1) |
79 |
* If we do not add alignment to mem_ptr then *(mem_ptr-1) points |
* If we do not add alignment to mem_ptr then *(mem_ptr-1) points |
80 |
* to a forbidden memory space |
* to a forbidden memory space */ |
|
*/ |
|
81 |
if (mem_ptr == tmp) |
if (mem_ptr == tmp) |
82 |
mem_ptr += alignment; |
mem_ptr += alignment; |
83 |
|
|
84 |
/* |
/* (mem_ptr - tmp) is stored in *(mem_ptr-1) so we are able to retrieve |
85 |
* (mem_ptr - tmp) is stored in *(mem_ptr-1) so we are able to retrieve |
* the real malloc block allocated and free it in xvid_free */ |
|
* the real malloc block allocated and free it in xvid_free |
|
|
*/ |
|
86 |
*(mem_ptr - 1) = (uint8_t) (mem_ptr - tmp); |
*(mem_ptr - 1) = (uint8_t) (mem_ptr - tmp); |
87 |
|
|
88 |
/* Return the aligned pointer */ |
/* Return the aligned pointer */ |
89 |
return (void *) mem_ptr; |
return ((void *)mem_ptr); |
|
|
|
90 |
} |
} |
91 |
} |
} |
92 |
|
|
93 |
return NULL; |
return(NULL); |
|
|
|
94 |
} |
} |
95 |
|
|
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 |
|
|
106 |
void |
void |
107 |
xvid_free(void *mem_ptr) |
xvid_free(void *mem_ptr) |
108 |
{ |
{ |
109 |
|
|
110 |
/* *(mem_ptr - 1) give us the offset to the real malloc block */ |
uint8_t *ptr; |
111 |
if (mem_ptr) |
|
112 |
free((uint8_t *) mem_ptr - *((uint8_t *) mem_ptr - 1)); |
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 |
|
|
122 |
|
/* Free the memory */ |
123 |
|
free(ptr); |
124 |
} |
} |