--- mem_align.c	2002/06/12 20:38:41	1.6
+++ mem_align.c	2003/06/09 13:55:38	1.15.2.2
@@ -1,7 +1,49 @@
+/*****************************************************************************
+ *
+ *  XVID MPEG-4 VIDEO CODEC
+ *  - Aligned Memory Allocator -
+ *
+ *  Copyright(C) 2002-2003 Edouard Gomez <ed.gomez@free.fr>
+ *
+ *  This program is free software ; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation ; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY ; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program ; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ * $Id: mem_align.c,v 1.15.2.2 2003/06/09 13:55:38 edgomez Exp $
+ *
+ ****************************************************************************/
+
 #include <stdlib.h>
 #include <stdio.h>
 #include "mem_align.h"
 
+/*****************************************************************************
+ * xvid_malloc
+ *
+ * This function allocates 'size' bytes (usable by the user) on the heap and
+ * takes care of the requested 'alignment'.
+ * In order to align the allocated memory block, the xvid_malloc allocates
+ * 'size' bytes + 'alignment' bytes. So try to keep alignment very small
+ * when allocating small pieces of memory.
+ *
+ * NB : a block allocated by xvid_malloc _must_ be freed with xvid_free
+ *      (the libc free will return an error)
+ *
+ * Returned value : - NULL on error
+ *                  - Pointer to the allocated aligned block
+ *
+ ****************************************************************************/
+
 void *
 xvid_malloc(size_t size,
 			uint8_t alignment)
@@ -14,10 +56,10 @@
 		if ((mem_ptr = (uint8_t *) malloc(size + 1)) != NULL) {
 
 			/* Store (mem_ptr - "real allocated memory") in *(mem_ptr-1) */
-			*mem_ptr = 0;
+			*mem_ptr = 1;
 
 			/* Return the mem_ptr pointer */
-			return (void *) mem_ptr++;
+			return (void *)(mem_ptr+1);
 
 		}
 
@@ -33,8 +75,8 @@
 
 			/* Align the tmp pointer */
 			mem_ptr =
-				(uint8_t *) ((uint32_t) (tmp + alignment - 1) &
-							 (~(uint32_t) (alignment - 1)));
+				(uint8_t *) ((ptr_t) (tmp + alignment - 1) &
+							 (~(ptr_t) (alignment - 1)));
 
 			/*
 			 * Special case where malloc have already satisfied the alignment
@@ -62,6 +104,16 @@
 
 }
 
+/*****************************************************************************
+ * xvid_free
+ *
+ * Free a previously 'xvid_malloc' allocated block. Does not free NULL
+ * references.
+ *
+ * Returned value : None.
+ *
+ ****************************************************************************/
+
 void
 xvid_free(void *mem_ptr)
 {