{														// inserted at all time, then you will
			intr = SL811Read(IntStatus);						// wait for interrupt to be done, and 
			if((intr & USB_RESET) || (intr & INSERT_REMOVE))	// proceed to parse result from slave 
			{													// device.
				DATA_STOP = TRUE;								// if device is removed, set DATA_STOP
				return FALSE;									// flag true, so that main loop will 
			}													// know this condition and exit gracefully
			if(intr & USB_A_DONE)								
				break;											// interrupt done !!!
		}

		SL811Write(IntStatus,INT_CLEAR); 						// clear interrupt status
		result 	  = SL811Read(EP0Status);						// read EP0status register
		remainder = SL811Read(EP0Counter);						// remainder value in last pkt xfer

		//-------------------------ACK----------------------------
		if (result & EP0_ACK)									// Transmission ACK
		{	

			// SETUP TOKEN
			if(pid == PID_SETUP)								// do nothing for SETUP/OUT token 
				break;											// exit while(1) immediately

			// OUT TOKEN				
			else if(pid == PID_OUT)
				break;

			// IN TOKEN
			else if(pid == PID_IN)
			{													// for IN token only
				wLen  -= (WORD)xferLen;							// update remainding wLen value
				cmd   ^= 0x40;    								// toggle DATA0/DATA1
				dataX++;										// point to next dataX

				//------------------------------------------------	
				// If host requested for more data than the slave 
				// have, and if the slave's data len is a multiple
				// of its endpoint payload size/last xferLen. Do 
				// not overwrite data in previous buffer.
				//------------------------------------------------	
				if(remainder==xferLen)							// empty data detected
					bufLen = 0;									// do not overwriten previous data
				else											// reset bufLen to zero
					bufLen = xferLen;							// update previous buffer length
				
				//------------------------------------------------	
				// Arm for next data transfer when requested data 
				// length have not reach zero, i.e. wLen!=0, and
				// last xferlen of data was completed, i.e.
				// remainder is equal to zero, not a short pkt
				//------------------------------------------------	
				if(!remainder && wLen)							// remainder==0 when last xferLen
				{												// was all completed or wLen!=0
					addr    = (dataX & 1) ? data1:data0; 		// select next address for data
					xferLen = (BYTE)(wLen>=wPayload) ? wPayload:wLen;	// get data length required
					if (FULL_SPEED)								// sync with SOF transfer
						cmd |= 0x20;							// always sync SOF when FS, regardless 
					SL811Write(EP0XferLen, xferLen); 			// select next xfer length
					SL811Write(EP0Address, addr);           	// data buffer addr 
					SL811Write(IntStatus,INT_CLEAR);			// is a LS is on Hub.
					SL811Write(EP0Control,cmd);					// Enable USB transfer and re-arm
				}				

				//------------------------------------------------
				// Copy last IN token data pkt from prev transfer
				// Check if there was data available during the
				// last data transfer
				//------------------------------------------------
				if(bufLen)										
				{	
					SL811BufRead(((dataX&1)?data0:data1), buffer, bufLen);
					buffer += bufLen;								
				}

				//------------------------------------------------
				// Terminate on short packets, i.e. remainder!=0
				// a short packet or empty data packet OR when 
				// requested data len have completed, i.e.wLen=0
				// For a LOWSPEED device, the 1st device descp,
				// wPayload is default to 64-byte, LS device will
				// only send back a max of 8-byte device descp,
				// and host detect this as a short packet, and 
				// terminate with OUT status stage
				//------------------------------------------------
				if(remainder || !wLen)
					break;
			}							
		}
		
		//-------------------------NAK----------------------------
		if (result & EP0_NAK)									// NAK Detected
		{														
			if(endpoint==0)										// on ep0 during enumeration of LS device
			{													// happen when slave is not fast enough,
				SL811Write(IntStatus,INT_CLEAR);				// clear interrupt status, need to
				SL811Write(EP0Control,cmd);						// re-arm and request for last cmd, IN token
                result = 0;                                     // respond to NAK status only
			}
			else												// normal data endpoint, exit now !!! , non-zero ep
				break;											// main loop control the interval polling
		}
		
		//-----------------------TIMEOUT--------------------------
		if (result & EP0_TIMEOUT)								// TIMEOUT Detected
		{														
			if(endpoint==0)										// happens when hub enumeration
			{
				if(++timeout >= TIMEOUT_RETRY)
				{	
				    timeout--;
					break;										// exit on the timeout detected	
				}
				SL811Write(IntStatus,INT_CLEAR);				// clear interrupt status, need to
				SL811Write(EP0Control,cmd);						// re-arm and request for last cmd again
			}
			else												
			{													// all other data endpoint, data transfer 
				TIMEOUT_ERR = TRUE;								// failed, set flag to terminate transfer
				break;											// happens when data transfer on a device
			}													// through the hub
		}

		//-----------------------STALL----------------------------
		if (result & EP0_STALL)  								// STALL detected
			return TRUE;										// for unsupported request.
																		
		//----------------------OVEFLOW---------------------------
		if (result & EP0_OVERFLOW)  							// OVERFLOW detected
			break;
		//-----------------------ERROR----------------------------
		if (result & EP0_ERROR)  								// ERROR detected
			break;
	}	// end of While(1)
   
	if (result & EP0_ACK) 	// on ACK transmission
		return TRUE;		// return OK

	return FALSE;			// fail transmission
}

//*****************************************************************************************
// Control Endpoint 0's USB Data Xfer
// ep0Xfer, endpoint 0 data transfer
//*****************************************************************************************
int ep0Xfer(BYTE usbaddr, WORD payload, pSetupPKG setup, BYTE *pData)
{
	xdata BYTE	pid  = PID_IN;
	xdata WORD	wLen = setup->wLength&0xFF; //WordSwap(setup->wLength);		// swap back for correct length
	xdata BYTE	ep0 = 0;								// always endpoint zero

	//----------------------------------------------------
	// SETUP token with 8-byte request on endpoint 0
	//----------------------------------------------------
	if (!usbXfer(usbaddr, ep0, PID_SETUP, 0, payload, 8, (BYTE*)setup)) 
   		return FALSE;

	//----------------------------------------------------
	// IN or OUT data stage on endpoint 0	
	//----------------------------------------------------
   	if (wLen)											// if there are data for transfer
	{
		if (setup->bmRequest & 0x80)					// host-to-device : IN token
		{
			pid  = PID_OUT;	
			if(!usbXfer(usbaddr, ep0, PID_IN, 0, payload, wLen, pData))
				return FALSE;
			payload = 0;
		}
		else											// device-to-host : OUT token
   		{							
			if(!usbXfer(usbaddr, ep0, PID_OUT, 0, payload, wLen, pData))
				return FALSE;
		}
	}

	//----------------------------------------------------
	// Status stage IN or OUT zero-length data packet
	//----------------------------------------------------
	if(!usbXfer(usbaddr, ep0, pid, 0, payload, 0, NULL))
		return FALSE;

	return TRUE;											
}

//*****************************************************************************************
// Control endpoint
//*****************************************************************************************
int VendorCmd(BYTE usbaddr,BYTE bReq,BYTE bCmd,WORD wValue,WORD wIndex,WORD wLen,BYTE *pData)
{ 
    xdata SetupPKG setup;

    setup.bmRequest  = bReq;
    setup.bRequest   = bCmd;
    setup.wValue     = wValue;
    setup.wIndex     = wIndex;
    setup.wLength    = wLen;	//WordSwap(wLen);

   	return ep0Xfer(usbaddr, uDev[usbaddr].wPayLoad[0], &setup, pData);
}

//*****************************************************************************************
// Set Device Address : 
//*****************************************************************************************
int SetAddress(WORD addr)
{
//	return VendorCmd(0,0,SET_ADDRESS, WordSwap(addr), 0, 0, NULL);
	return VendorCmd(0,0,SET_ADDRESS, addr, 0, 0, NULL);
}

//*****************************************************************************************
// Set Device Configuration : 
//*****************************************************************************************
int Set_Configuration(BYTE usbaddr, WORD wVal)
{
	return VendorCmd(usbaddr, 0, SET_CONFIG, WordSwap(wVal), 0, 0, NULL);
//	return VendorCmd(usbaddr, 0, SET_CONFIG, wVal, 0, 0, NULL);
}

//*****************************************************************************************
// Get Device Descriptor : Device, Configuration, String
//*****************************************************************************************
int GetDesc(BYTE usbaddr, WORD wValue, 	WORD wIndex, WORD wLen, BYTE *desc)
{ 
	return VendorCmd(usbaddr, 0x80, GET_DESCRIPTOR, wValue, wIndex, wLen, desc);
}

//*****************************************************************************************
// HID Get_Desc :
//*****************************************************************************************
int GetHid_Desc(BYTE usbaddr, WORD wValue, WORD wLen, BYTE *desc)
{ 
	return VendorCmd(usbaddr, 0x81, GET_DESCRIPTOR, wValue, 0, wLen, desc);
}

//*****************************************************************************************
// GetHUBDesc :
//*****************************************************************************************
int GetHubDesc(BYTE usbaddr, WORD wValue, WORD wLen, BYTE *desc)
{ 
	return VendorCmd(usbaddr, 0xA0, GET_DESCRIPTOR, wValue, 0, wLen, desc);
}

//*****************************************************************************************
// Get Status : (HUB)
//*****************************************************************************************
int GetStatus(BYTE usbaddr, BYTE *desc)
{ 
	return VendorCmd(usbaddr, 0x80, GET_STATUS, 0, 0, 2, desc);		 
}

//*****************************************************************************************
// PortFeature : (SET_FEATURE, CLEAR_FEATURE)
//*****************************************************************************************
int PortFeature(BYTE usbaddr, BYTE bReq, WORD wValue, BYTE cPort)
{ 
//	return VendorCmd(usbaddr, 0x23, bReq, WordSwap(wValue), WordSwap((WORD)cPort), 0, NULL);	
	return VendorCmd(usbaddr, 0x23, bReq, wValue, cPort, 0, NULL);
}

//*****************************************************************************************
// GetPortStatus :
//*****************************************************************************************
int GetPortStatus(BYTE usbaddr, BYTE cPort, BYTE *desc)
{ 
//	return VendorCmd(usbaddr, 0xA3, GET_STATUS, 0, WordSwap((WORD)cPort), 0x04, desc);
	return VendorCmd(usbaddr, 0xA3, GET_STATUS, 0, cPort, 0x04, desc);
}


//*****************************************************************************************
// USB Data Endpoint Read/Write
// wLen is in low byte first format
//*****************************************************************************************
int DataRW(BYTE usbaddr, BYTE epaddr, WORD wPayload, WORD wLen, BYTE *pData)
{
	xdata BYTE pid = PID_OUT;

	if(epaddr & 0x80)	// get direction of transfer
		pid = PID_IN;				

	if(usbXfer(usbaddr,epaddr&0x0F,pid,0,wPayload,wLen,pData))
		return TRUE;

	return FALSE;
}

//*****************************************************************************************
// USB Device Enumeration Process
// Support 1 confguration and interface #0 and alternate setting #0 only
// Support up to 1 control endpoint + 4 data endpoint only
//*****************************************************************************************
int EnumUsbDev(BYTE usbaddr)
{  
	int i;											// always reset USB transfer address 
	xdata BYTE uAddr = 0;							// for enumeration to Address #0
	xdata BYTE epLen;
	xdata WORD strLang;

	//------------------------------------------------
	// Reset only Slave device attached directly
	//------------------------------------------------
	uDev[0].wPayLoad[0] = 64;						// default 64-byte payload of Endpoint 0, address #0
	if(usbaddr == 1)								// bus reset for the device attached to SL811HS only
		USBReset();									// that will always have the USB address = 0x01 (for a hub)
    EZUSB_Delay(25);

	//------------------------------------------------
	// Get USB Device Descriptors on EP0 & Addr 0
	// with default 64-byte payload
	//------------------------------------------------
	pDev =(pDevDesc)DBUF;							// ask for 64 bytes on Addr #0
	if (!GetDesc(uAddr,DEVICE,0,18,DBUF))			// and determine the wPayload size
		return FALSE;								// get correct wPayload of Endpoint 0
	uDev[usbaddr].wPayLoad[0]=pDev->bMaxPacketSize0;// on current non-zero USB address

	//------------------------------------------------
	// Set Slave USB Device Address
	//------------------------------------------------
	if (!SetAddress(usbaddr)) 						// set to specific USB address
		return FALSE;								//
	uAddr = usbaddr;								// transfer using this new address

	//------------------------------------------------
	// Get USB Device Descriptors on EP0 & Addr X