--- mem_align.c	2002/03/21 00:28:33	1.3
+++ mem_align.c	2002/06/12 20:38:41	1.6
@@ -2,25 +2,59 @@
 #include <stdio.h>
 #include "mem_align.h"
 
-void *xvid_malloc(size_t size, uint8_t alignment)
+void *
+xvid_malloc(size_t size,
+			uint8_t alignment)
 {
 	uint8_t *mem_ptr;
-  
-	if(alignment == 0)
-	{
-		if((mem_ptr = (uint8_t *) malloc(size + 1)) != NULL) {
+
+	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 = 0;
+
+			/* Return the mem_ptr pointer */
 			return (void *) mem_ptr++;
+
 		}
-	}
-	else
-	{
+
+	} else {
 		uint8_t *tmp;
-	
-		if((tmp = (uint8_t *) malloc(size + alignment)) != NULL) {
-			mem_ptr = (uint8_t *)((uint32_t)(tmp + alignment - 1)&(~(uint32_t)(alignment - 1)));
-			*(mem_ptr - 1) = (uint8_t)(mem_ptr - 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 *) ((uint32_t) (tmp + alignment - 1) &
+							 (~(uint32_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;
+
 		}
 	}
 
@@ -28,13 +62,12 @@
 
 }
 
-void xvid_free(void *mem_ptr)
+void
+xvid_free(void *mem_ptr)
 {
 
-	uint8_t *real_ptr;
-
-	real_ptr = (uint8_t*)mem_ptr;
-
-	free(real_ptr - *(real_ptr -1));
+	/* *(mem_ptr - 1) give us the offset to the real malloc block */
+	if (mem_ptr)
+		free((uint8_t *) mem_ptr - *((uint8_t *) mem_ptr - 1));
 
 }