--- mem_align.c	2002/03/08 02:44:58	1.1.1.1
+++ mem_align.c	2004/03/22 22:36:24	1.16
@@ -0,0 +1,124 @@
+/*****************************************************************************
+ *
+ *  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 1.16 2004/03/22 22:36:24 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)
+{
+	uint8_t *mem_ptr;
+
+	if (!alignment) {
+
+		/* We have not to satisfy any alignment */
+		if ((mem_ptr = (uint8_t *) malloc(size + 1)) != NULL) {
+
+			/* Store (mem_ptr - "real allocated memory") in *(mem_ptr-1) */
+			*mem_ptr = (uint8_t)1;
+
+			/* Return the mem_ptr pointer */
+			return ((void *)(mem_ptr+1));
+		}
+	} else {
+		uint8_t *tmp;
+
+		/* Allocate the required size memory + alignment so we
+		 * can realign the data if necessary */
+		if ((tmp = (uint8_t *) malloc(size + alignment)) != NULL) {
+
+			/* Align the tmp pointer */
+			mem_ptr =
+				(uint8_t *) ((ptr_t) (tmp + alignment - 1) &
+							 (~(ptr_t) (alignment - 1)));
+
+			/* Special case where malloc have already satisfied the alignment
+			 * We must add alignment to mem_ptr because we must store
+			 * (mem_ptr - tmp) in *(mem_ptr-1)
+			 * If we do not add alignment to mem_ptr then *(mem_ptr-1) points
+			 * to a forbidden memory space */
+			if (mem_ptr == tmp)
+				mem_ptr += alignment;
+
+			/* (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 */
+			*(mem_ptr - 1) = (uint8_t) (mem_ptr - tmp);
+
+			/* Return the aligned pointer */
+			return ((void *)mem_ptr);
+		}
+	}
+
+	return(NULL);
+}
+
+/*****************************************************************************
+ * xvid_free
+ *
+ * Free a previously 'xvid_malloc' allocated block. Does not free NULL
+ * references.
+ *
+ * Returned value : None.
+ *
+ ****************************************************************************/
+
+void
+xvid_free(void *mem_ptr)
+{
+
+	uint8_t *ptr;
+
+	if (mem_ptr == NULL)
+		return;
+
+	/* Aligned pointer */
+	ptr = mem_ptr;
+
+	/* *(ptr - 1) holds the offset to the real allocated block
+	 * we sub that offset os we free the real pointer */
+	ptr -= *(ptr - 1);
+
+	/* Free the memory */
+	free(ptr);
+}