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Diff of /xvidcore/src/utils/mem_align.c

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revision 1.15, Sat Feb 15 15:22:19 2003 UTC revision 1.16, Mon Mar 22 22:36:24 2004 UTC
# Line 1  Line 1 
1  /*****************************************************************************  /*****************************************************************************
2   *   *
3   *  XVID MPEG-4 VIDEO CODEC   *  XVID MPEG-4 VIDEO CODEC
4   *  - Aligned memory allocator -   *  - Aligned Memory Allocator -
5   *   *
6   *  This program is an implementation of a part of one or more MPEG-4   *  Copyright(C) 2002-2003 Edouard Gomez <ed.gomez@free.fr>
  *  Video tools as specified in ISO/IEC 14496-2 standard.  Those intending  
  *  to use this software module in hardware or software products are  
  *  advised that its use may infringe existing patents or copyrights, and  
  *  any such use would be at such party's own risk.  The original  
  *  developer of this software module and his/her company, and subsequent  
  *  editors and their companies, will have no liability for use of this  
  *  software or modifications or derivatives thereof.  
7   *   *
8   *  This program is free software ; you can redistribute it and/or modify   *  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   *  it under the terms of the GNU General Public License as published by
# Line 26  Line 19 
19   *  along with this program ; if not, write to the Free Software   *  along with this program ; if not, write to the Free Software
20   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
21   *   *
  ****************************************************************************/  
 /*****************************************************************************  
  *  
  *  History  
  *  
  *  - Thu Jun 13 23:50:07 2002 Added legal header  
  *  
22   *  $Id$   *  $Id$
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"
# Line 71  Line 56 
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 = 1;                          *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 */
# Line 93  Line 73 
73                                  (uint8_t *) ((ptr_t) (tmp + alignment - 1) &                                  (uint8_t *) ((ptr_t) (tmp + alignment - 1) &
74                                                           (~(ptr_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  /*****************************************************************************  /*****************************************************************************
# Line 133  Line 107 
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  }  }

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