diff --git a/reactos/ntoskrnl/ex/zone.c b/reactos/ntoskrnl/ex/zone.c
index e70f3c3f7ac..16405705983 100644
--- a/reactos/ntoskrnl/ex/zone.c
+++ b/reactos/ntoskrnl/ex/zone.c
@@ -1,57 +1,68 @@
-/* $Id$
- *
+/*
  * COPYRIGHT:       See COPYING in the top level directory
  * PROJECT:         ReactOS kernel
- * FILE:            ntoskrnl/mm/zone.c
+ * FILE:            ntoskrnl/ex/zone.c
  * PURPOSE:         Implements zone buffers
  *
- * PROGRAMMERS:     David Welch (welch@mcmail.com)
+ * PROGRAMMERS:     Alex Ionescu (alex@relsoft.net)
+ *                  David Welch (welch@mcmail.com)
  */
 
 /* INCLUDES ****************************************************************/
 
 #include <ntoskrnl.h>
+#define NDEBUG
+#include <debug.h>
 
 /* FUNCTIONS ***************************************************************/
 
-// undocumented? from extypes.h in here for now...
-
-//typedef struct _ZONE_ENTRY
-//{
-//   SINGLE_LIST_ENTRY Entry;
-//} ZONE_ENTRY, *PZONE_ENTRY;
-
-
-
 /*
  * @implemented
  */
 NTSTATUS
 STDCALL
-ExExtendZone (
-	PZONE_HEADER	Zone,
-	PVOID		Segment,
-	ULONG		SegmentSize
-	)
+ExExtendZone(PZONE_HEADER Zone,
+             PVOID Segment,
+             ULONG SegmentSize)
 {
-   PZONE_SEGMENT_HEADER entry;
-   PZONE_SEGMENT_HEADER seg;
-   unsigned int i;
+    ULONG_PTR Entry;
+    ULONG i;
 
-   seg = (PZONE_SEGMENT_HEADER)Segment;
-   seg->Reserved = (PVOID) SegmentSize;
+    /* 
+     * BlockSize and Segment must be 8-byte aligned.
+     * Blocksize cannot exceed Segment Size.
+     */
+    if (((ULONG_PTR)Segment & 7) || 
+        (SegmentSize & 7) || 
+        (Zone->BlockSize > SegmentSize))
+    {
+        DPRINT1("Invalid ExExtendZone Alignment and/or Size\n");
+        return STATUS_INVALID_PARAMETER;
+    }
 
-   PushEntryList(&Zone->SegmentList,&seg->SegmentList);
+    /* Link the Zone and Segment */
+    PushEntryList(&Zone->SegmentList,&((PZONE_SEGMENT_HEADER)Segment)->SegmentList);
 
-   entry = (PZONE_SEGMENT_HEADER)( ((char*)seg) + sizeof(ZONE_SEGMENT_HEADER) );
+    /* Get to the first entry */
+    Entry = (ULONG_PTR)Segment + sizeof(ZONE_SEGMENT_HEADER);
 
-   for (i=0;i<(SegmentSize / Zone->BlockSize);i++)
-     {
-	PushEntryList(&Zone->FreeList,&entry->SegmentList);
-	entry = (PZONE_SEGMENT_HEADER)(((char*)entry) + sizeof(PZONE_SEGMENT_HEADER) +
-			      Zone->BlockSize);
-     }
-   return(STATUS_SUCCESS);
+    /* Loop through the segments */
+    for (i = sizeof(ZONE_SEGMENT_HEADER);
+         i <= SegmentSize - Zone->BlockSize;
+         i+= Zone->BlockSize)
+    {
+        /* Link the Free and Segment Lists */
+        PushEntryList(&Zone->FreeList, (PSINGLE_LIST_ENTRY)Entry);
+
+        /* Go to the next entry */
+        Entry += Zone->BlockSize;
+    }
+
+    /* Update Segment Size */
+    Zone->TotalSegmentSize += i;
+
+    /* Return Success */
+    return STATUS_SUCCESS;
 }
 
 
@@ -60,34 +71,26 @@ ExExtendZone (
  */
 NTSTATUS
 STDCALL
-ExInterlockedExtendZone (
-	PZONE_HEADER	Zone,
-	PVOID		Segment,
-	ULONG		SegmentSize,
-	PKSPIN_LOCK	Lock
-	)
+ExInterlockedExtendZone(PZONE_HEADER Zone,
+                        PVOID Segment,
+                        ULONG SegmentSize,
+                        PKSPIN_LOCK	Lock)
 {
-   NTSTATUS ret;
-   KIRQL oldlvl;
+    NTSTATUS Status;
+    KIRQL OldIrql;
 
-   KeAcquireSpinLock(Lock,&oldlvl);
-   ret = ExExtendZone(Zone,Segment,SegmentSize);
-   KeReleaseSpinLock(Lock,oldlvl);
-   return(ret);
+    /* Get the lock */
+    KeAcquireSpinLock(Lock, &OldIrql);
+
+    /* Extend the Zone */
+    Status = ExExtendZone(Zone, Segment, SegmentSize);
+
+    /* Release lock and return status */
+    KeReleaseSpinLock(Lock, OldIrql);
+    return Status;
 }
 
 
-/*
- * @implemented
- */
-NTSTATUS
-STDCALL
-ExInitializeZone (
-	PZONE_HEADER	Zone,
-	ULONG		BlockSize,
-	PVOID		InitialSegment,
-	ULONG		InitialSegmentSize
-	)
 /*
  * FUNCTION: Initalizes a zone header
  * ARGUMENTS:
@@ -96,31 +99,60 @@ ExInitializeZone (
  *          InitialSegment = Initial segment of storage allocated by the
  *                           caller
  *          InitialSegmentSize = Initial size of the segment
+ *
+ * @implemented
  */
+NTSTATUS
+STDCALL
+ExInitializeZone(PZONE_HEADER Zone,
+                 ULONG BlockSize,
+                 PVOID InitialSegment,
+                 ULONG InitialSegmentSize)
 {
-   unsigned int i;
-   PZONE_SEGMENT_HEADER seg;
-   PZONE_SEGMENT_HEADER entry;
+    ULONG i;
+    ULONG_PTR Entry;
 
-   Zone->FreeList.Next=NULL;
-   Zone->SegmentList.Next=NULL;
-   Zone->BlockSize=BlockSize;
-   Zone->TotalSegmentSize = InitialSegmentSize;
+    /* 
+     * BlockSize and Segment must be 8-byte aligned.
+     * Blocksize cannot exceed Segment Size.
+     */
+    if (((ULONG_PTR)InitialSegment & 7) ||
+        (InitialSegmentSize & 7) ||
+        (BlockSize > InitialSegmentSize))
+    {
+        DPRINT1("Invalid ExInitializeZone Alignment and/or Size\n");
+        return STATUS_INVALID_PARAMETER;
+    }
 
-   seg = (PZONE_SEGMENT_HEADER)InitialSegment;
-   seg->Reserved = (PVOID*) InitialSegmentSize;
+    /* Set the Zone Header */
+    Zone->BlockSize = BlockSize;
 
-   PushEntryList(&Zone->SegmentList,&seg->SegmentList);
+    /* Link empty list */
+    Zone->FreeList.Next = NULL;
+    Zone->SegmentList.Next = NULL;
+    PushEntryList(&Zone->SegmentList, &((PZONE_SEGMENT_HEADER)InitialSegment)->SegmentList);
+    ((PZONE_SEGMENT_HEADER)InitialSegment)->Reserved = NULL;
 
-   entry = (PZONE_SEGMENT_HEADER)( ((char*)seg) + sizeof(ZONE_SEGMENT_HEADER) );
+    /* Get first entry */
+    Entry = (ULONG_PTR)InitialSegment + sizeof(ZONE_SEGMENT_HEADER);
 
-   for (i=0;i<(InitialSegmentSize / BlockSize);i++)
-     {
-	PushEntryList(&Zone->FreeList,&entry->SegmentList);
-	entry = (PZONE_SEGMENT_HEADER)(((char*)entry) + sizeof(PZONE_SEGMENT_HEADER) + BlockSize);
-     }
+    /* Loop through the segments */
+    for (i = sizeof(ZONE_SEGMENT_HEADER);
+         i <= InitialSegmentSize - BlockSize;
+         i+= BlockSize)
+    {
+        /* Link the Free and Segment Lists */
+        PushEntryList(&Zone->FreeList, (PSINGLE_LIST_ENTRY)Entry);
 
-   return(STATUS_SUCCESS);
+        /* Go to the next entry */
+        Entry += Zone->BlockSize;
+    }
+
+    /* Update Segment Size */
+    Zone->TotalSegmentSize += i;
+
+    /* Return success */
+    return STATUS_SUCCESS;
 }
 
 /* EOF */