usb host

Hello Sir,

I am working on USB host for HID class using LPC2468 controller . I am using USB Hostlite
example as a base . I made this code compatible for both full speed and low speed hid device.
Now i am trying to create USB Device instance for that i have structure declaration as shown in following code.

struct  usb_device_instance     {
UWORD8  *p_USB_DeviceDescriptor;
UWORD8  *p_USB_ConfigDescriptor;
UWORD8  *p_USB_StringDescriptor;
UWORD8  *p_HID_ReportDescriptor;

UWORD8  bUSB_DeviceAddress;             /* USB bus address */
UWORD8  bUSB_Configuration;             /* current configuration number */
//UWORD16       wUSB_DeviceStatus;              /* bits 15-3 = 0; bit(1) = Remote Wakeup; bit(0) = Self Powered */

                        /* bits 31-16: input endpoints; bits 15-0: output endpoints */
//UWORD32       fg_USB_EndPointMask;    /*  working endpoints for current configuration */
//UWORD32       fg_USB_EndPointHalt;    /*  HALTED working endpoints for current configuration */

UWORD8  ep0_bMaxPacketSize;             /* maximum packet size declared in Device Descriptor */
UWORD8  bNumConfigurations;
UWORD8  bNumInterfaces;         /*  number of interfaces for current configuration */
UWORD8  bMaxNumInterfaces;      /* Maximum number of interfaces for all possible configurations */
UWORD8  bNumStrings;                            /* number of strings */
UWORD8  bNumReportDescriptors;  /* number of report descriptors */

//UWORD8        *p_bEP0Buf;                             /*  working buffer for Control Transfer ep0 */
UWORD8  *p_bAltSetting_perIFC;  /*  Alternate Setting No. per Interfaces for current configuration */

UWORD8  *p_bHID_Protocol;
//UWORD8        *p_bHID_IdleTime;
//UWORD8        *p_bHID_IdleCount;

UWORD8  bIFCs_ready;
struct usb_IFC_instance  *p_IFCs;
UWORD32 fg_queue_IFCs;           /* bits 31-16: IFCs of IN transfer requests; bits 15-0: IFCs of Out (or Feature) transfer requests; */

//CB_USB_Rx_Handler *p_callback_Rx_handler;     /* User's handler Function for output and feature reports */
//CB_USB_BufMapping *p_callback_bufMapping;
struct HID_repDesc_info *p_subRepDescriptor;  /*  information block of report descriptors */

UWORD8  *p_head_RIDinfo;
UWORD8 wSize_ConfigDescriptor;
UWORD8 wSize_StringDescriptor;
UWORD8 wSize_ReportDescriptor;
};

I am facing a problem when i take a pointer of this type as shown below
struct usb_device_instance *p_usbD ;

when I debug through the software i observe that this is taking address 0x00000000.
I don,t want to use this address I have already used ram upto 0x4000F8D8.
I just want to confirm that can there be a special address like TD buffer has special address 0x7FD00150.

One more thing i want to confirm that in case of mass storage class data comes in Userbuffer .
In this case from which buffer we have to check data.

Thanks & Regars
R.kumar