diff --git a/reactos/dll/directx/ddraw/main.c b/reactos/dll/directx/ddraw/main.c
index 88051f8923c..5fb175e8e44 100644
--- a/reactos/dll/directx/ddraw/main.c
+++ b/reactos/dll/directx/ddraw/main.c
@@ -145,36 +145,34 @@ D3DParseUnknownCommand( LPVOID lpCmd,
     DWORD retCode = D3DERR_COMMAND_UNPARSED; 
     
     /* prevent it crash if null pointer are being sent */
-    if (lpCmd == NULL) || (lpRetCmd == NULL) )
+    if ( (lpCmd == NULL) || (lpRetCmd == NULL) )
     {
         return E_FAIL;
     }
     
     *lpRetCmd = lpCmd;
     
+    /* check for vaild command, only 3 command is vaild */
     if (dp2command->bCommand == D3DDP2OP_VIEWPORTINFO) 
-    {    			
-        *(PBYTE)lpRetCmd += ((dp2command->wStateCount * sizeof(D3DHAL_DP2VIEWPORTINFO)) + sizeof(D3DHAL_DP2POINTS));
+    {    	
+        /* dp2command->wStateCount * sizeof D3DHAL_DP2VIEWPORTINFO + 4 bytes */
+        *(PBYTE)lpRetCmd += ((dp2command->wStateCount * sizeof(D3DHAL_DP2VIEWPORTINFO)) + sizeof(ULONG_PTR));
         retCode = 0;
     }                                                                                          
     else if (dp2command->bCommand == D3DDP2OP_WINFO) 
-    {			        
-        *(PBYTE)lpRetCmd += (dp2command->wStateCount * sizeof(D3DHAL_DP2WINFO)) + sizeof(D3DHAL_DP2POINTS);                                                          
+    {	
+        /* dp2command->wStateCount * sizeof D3DHAL_DP2WINFO + 4 bytes */
+        *(PBYTE)lpRetCmd += (dp2command->wStateCount * sizeof(D3DHAL_DP2WINFO)) + sizeof(ULONG_PTR);                                                          
         retCode = 0;
     } 
 	else if (dp2command->bCommand == 0x0d) 
-    {	   
-		/* math  
-		     *lpRetCmd = lpCmd + (wStateCount * sizeof( ? ) + sizeof(D3DHAL_DP2POINTS) 
-		 */
-
-        *(PBYTE)lpRetCmd += ((dp2command->wStateCount * dp2command->bReserved) + sizeof(D3DHAL_DP2POINTS));               
+    {	
+        /* dp2command->wStateCount * how many wStateCount ? + 4 bytes */
+        *(PBYTE)lpRetCmd += ((dp2command->wStateCount * dp2command->bReserved) + sizeof(ULONG_PTR));               
         retCode = 0;
     }
    
-
-	/* error code */
-    
+	/* set error code for command 0 to 3, 8 and 15 to 255 */    
     else if ( (dp2command->bCommand <= D3DDP2OP_INDEXEDTRIANGLELIST) || // dp2command->bCommand  <= with 0 to 3
               (dp2command->bCommand == D3DDP2OP_RENDERSTATE) ||  // dp2command->bCommand  == with 8
               (dp2command->bCommand >= D3DDP2OP_LINELIST) )  // dp2command->bCommand  >= with 15 to 255