fix(usb): support bidirectional endpoints on RP2 and SAMD21/51.

Remap CDC and MSC endpoints to share physical endpoint numbers. This change separates IN/OUT directional states for RP2 endpoints to prevent cross-talk, ensures SAMD21 and SAMD51 endpoint configuration merging does not overwrite bidirectionally shared registers, implements missing SAMD endpoint stall and clear methods, and corrects SAMD interrupt loop bounds to iterate over physical endpoint numbers rather than dynamic configuration entries.

src/machine/machine_atsamd21_usb.go

@@ -175,7 +175,7 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 
 	// Now the actual transfer handlers, ignore endpoint number 0 (setup)
 	var i uint32
-	for i = 1; i < uint32(len(endPoints)); i++ {
+	for i = 1; i < NumberOfUSBEndpoints; i++ {
 		// Check if endpoint has a pending interrupt
 		epFlags := getEPINTFLAG(i)
 		setEPINTFLAG(i, epFlags)
@@ -193,6 +193,8 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 }
 
 func initEndpoint(ep, config uint32) {
+	// Note: Both IN (Bank 1) and OUT (Bank 0) configurations share the same EPCFG register.
+	// We must use getEPCFG(ep) | ... to avoid clearing/disabling the opposite direction.
 	switch config {
 	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn:
 		// set packet size
@@ -202,7 +204,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_INTERRUPT + 1) << sam.USB_DEVICE_EPCFG_EPTYPE1_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_INTERRUPT+1)<<sam.USB_DEVICE_EPCFG_EPTYPE1_Pos))
 
 		setEPINTENSET(ep, sam.USB_DEVICE_EPINTENSET_TRCPT1)
 
@@ -214,7 +216,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[0].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_BULK + 1) << sam.USB_DEVICE_EPCFG_EPTYPE0_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_BULK+1)<<sam.USB_DEVICE_EPCFG_EPTYPE0_Pos))
 
 		// receive interrupts when current transfer complete
 		setEPINTENSET(ep, sam.USB_DEVICE_EPINTENSET_TRCPT0)
@@ -233,7 +235,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[0].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_INTERRUPT + 1) << sam.USB_DEVICE_EPCFG_EPTYPE0_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_INTERRUPT+1)<<sam.USB_DEVICE_EPCFG_EPTYPE0_Pos))
 
 		// receive interrupts when current transfer complete
 		setEPINTENSET(ep, sam.USB_DEVICE_EPINTENSET_TRCPT0)
@@ -252,7 +254,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_BULK + 1) << sam.USB_DEVICE_EPCFG_EPTYPE1_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_BULK+1)<<sam.USB_DEVICE_EPCFG_EPTYPE1_Pos))
 
 		// NAK on endpoint IN, the bank is not yet filled in.
 		setEPSTATUSCLR(ep, sam.USB_DEVICE_EPSTATUSCLR_BK1RDY)
@@ -650,3 +652,19 @@ func setEPINTENSET(ep uint32, val uint8) {
 		return
 	}
 }
+
+func (dev *USBDevice) SetStallEPIn(ep uint32) {
+	setEPSTATUSSET(ep, sam.USB_DEVICE_EPSTATUSSET_STALLRQ1)
+}
+
+func (dev *USBDevice) SetStallEPOut(ep uint32) {
+	setEPSTATUSSET(ep, sam.USB_DEVICE_EPSTATUSSET_STALLRQ0)
+}
+
+func (dev *USBDevice) ClearStallEPIn(ep uint32) {
+	setEPSTATUSCLR(ep, sam.USB_DEVICE_EPSTATUSCLR_STALLRQ1)
+}
+
+func (dev *USBDevice) ClearStallEPOut(ep uint32) {
+	setEPSTATUSCLR(ep, sam.USB_DEVICE_EPSTATUSCLR_STALLRQ0)
+}

src/machine/machine_atsamd51_usb.go

@@ -178,7 +178,7 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 
 	// Now the actual transfer handlers, ignore endpoint number 0 (setup)
 	var i uint32
-	for i = 1; i < uint32(len(endPoints)); i++ {
+	for i = 1; i < NumberOfUSBEndpoints; i++ {
 		// Check if endpoint has a pending interrupt
 		epFlags := getEPINTFLAG(i)
 		setEPINTFLAG(i, epFlags)
@@ -196,6 +196,8 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 }
 
 func initEndpoint(ep, config uint32) {
+	// Note: Both IN (Bank 1) and OUT (Bank 0) configurations share the same EPCFG register.
+	// We must use getEPCFG(ep) | ... to avoid clearing/disabling the opposite direction.
 	switch config {
 	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn:
 		// set packet size
@@ -205,7 +207,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_INTERRUPT + 1) << sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE1_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_INTERRUPT+1)<<sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE1_Pos))
 
 		setEPINTENSET(ep, sam.USB_DEVICE_ENDPOINT_EPINTENSET_TRCPT1)
 
@@ -217,7 +219,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[0].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_BULK + 1) << sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE0_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_BULK+1)<<sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE0_Pos))
 
 		// receive interrupts when current transfer complete
 		setEPINTENSET(ep, sam.USB_DEVICE_ENDPOINT_EPINTENSET_TRCPT0)
@@ -236,7 +238,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[0].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_INTERRUPT + 1) << sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE0_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_INTERRUPT+1)<<sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE0_Pos))
 
 		// receive interrupts when current transfer complete
 		setEPINTENSET(ep, sam.USB_DEVICE_ENDPOINT_EPINTENSET_TRCPT0)
@@ -255,7 +257,7 @@ func initEndpoint(ep, config uint32) {
 		usbEndpointDescriptors[ep].DeviceDescBank[1].ADDR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_in_cache_buffer[ep]))))
 
 		// set endpoint type
-		setEPCFG(ep, ((usb.ENDPOINT_TYPE_BULK + 1) << sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE1_Pos))
+		setEPCFG(ep, getEPCFG(ep)|((usb.ENDPOINT_TYPE_BULK+1)<<sam.USB_DEVICE_ENDPOINT_EPCFG_EPTYPE1_Pos))
 
 		// NAK on endpoint IN, the bank is not yet filled in.
 		setEPSTATUSCLR(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSCLR_BK1RDY)
@@ -481,3 +483,19 @@ func setEPINTENCLR(ep uint32, val uint8) {
 func setEPINTENSET(ep uint32, val uint8) {
 	sam.USB_DEVICE.DEVICE_ENDPOINT[ep].EPINTENSET.Set(val)
 }
+
+func (dev *USBDevice) SetStallEPIn(ep uint32) {
+	setEPSTATUSSET(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSSET_STALLRQ1)
+}
+
+func (dev *USBDevice) SetStallEPOut(ep uint32) {
+	setEPSTATUSSET(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSSET_STALLRQ0)
+}
+
+func (dev *USBDevice) ClearStallEPIn(ep uint32) {
+	setEPSTATUSCLR(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSCLR_STALLRQ1)
+}
+
+func (dev *USBDevice) ClearStallEPOut(ep uint32) {
+	setEPSTATUSCLR(ep, sam.USB_DEVICE_ENDPOINT_EPSTATUSCLR_STALLRQ0)
+}

src/machine/machine_rp2_usb.go

@@ -20,38 +20,56 @@ var (
 
 func initEndpoint(ep, config uint32) {
 	val := uint32(usbEpControlEnable) | uint32(usbEpControlInterruptPerBuff)
+
+	// Each endpoint has 128 bytes of DPRAM buffer space allocated (2 * usbBufferLen).
+	// To support bidirectional configurations using the same endpoint number,
+	// we allocate the first 64 bytes (Buffer0) to OUT transfers, and the remaining
+	// 64 bytes (Buffer1) to IN transfers by shifting the IN offset by usbBufferLen.
 	offset := ep*2*usbBufferLen + 0x100
-	val |= offset
 
 	// Bulk and interrupt endpoints must have their Packet ID reset to DATA0 when un-stalled.
-	epXPIDReset[ep] = false // Default to false in case an endpoint is re-initialized.
+	// Since both directions share the same ep, we reset their PID flags independently.
+	if (config & usb.EndpointIn) != 0 {
+		epXPIDResetIn[ep] = false
+	} else {
+		epXPIDResetOut[ep] = false
+	}
 
 	switch config {
 	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn:
+		epXPIDResetIn[ep] = true
+		epXdata0In[ep] = false
+		val |= offset + usbBufferLen
 		val |= usbEpControlEndpointTypeInterrupt
 		_usbDPSRAM.EPxControl[ep].In.Set(val)
-		epXPIDReset[ep] = true
 
 	case usb.ENDPOINT_TYPE_BULK | usb.EndpointOut:
+		epXPIDResetOut[ep] = true
+		epXdata0Out[ep] = false
+		val |= offset
 		val |= usbEpControlEndpointTypeBulk
 		_usbDPSRAM.EPxControl[ep].Out.Set(val)
 		_usbDPSRAM.EPxBufferControl[ep].Out.Set(usbBufferLen & usbBuf0CtrlLenMask)
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
-		epXPIDReset[ep] = true
 
 	case usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointOut:
+		epXPIDResetOut[ep] = true
+		epXdata0Out[ep] = false
+		val |= offset
 		val |= usbEpControlEndpointTypeInterrupt
 		_usbDPSRAM.EPxControl[ep].Out.Set(val)
 		_usbDPSRAM.EPxBufferControl[ep].Out.Set(usbBufferLen & usbBuf0CtrlLenMask)
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
-		epXPIDReset[ep] = true
 
 	case usb.ENDPOINT_TYPE_BULK | usb.EndpointIn:
+		epXPIDResetIn[ep] = true
+		epXdata0In[ep] = false
+		val |= offset + usbBufferLen
 		val |= usbEpControlEndpointTypeBulk
 		_usbDPSRAM.EPxControl[ep].In.Set(val)
-		epXPIDReset[ep] = true
 
 	case usb.ENDPOINT_TYPE_CONTROL:
+		val |= offset
 		val |= usbEpControlEndpointTypeControl
 		_usbDPSRAM.EPxBufferControl[ep].Out.Set(usbBuf0CtrlData1Pid)
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
@@ -79,7 +97,7 @@ func sendUSBPacket(ep uint32, data []byte) {
 		} else {
 			sendOnEP0DATADONE.offset = 0
 		}
-		epXdata0[ep] = true
+		epXdata0In[ep] = true
 	}
 
 	sendViaEPIn(ep, data, count)
@@ -116,19 +134,29 @@ func handleEndpointRx(ep uint32) []byte {
 // AckUsbOutTransfer is called to acknowledge the completion of a USB OUT transfer.
 func AckUsbOutTransfer(ep uint32) {
 	ep = ep & 0x7F
-	setEPDataPID(ep, !epXdata0[ep])
+	setEPDataPIDOut(ep, !epXdata0Out[ep])
 }
 
-// Set the USB endpoint Packet ID to DATA0 or DATA1.
+// Set the USB endpoint Packet ID to DATA0 or DATA1 for OUT direction.
-func setEPDataPID(ep uint32, dataOne bool) {
+func setEPDataPIDOut(ep uint32, dataOne bool) {
-	epXdata0[ep] = dataOne
+	epXdata0Out[ep] = dataOne
-	if epXdata0[ep] || ep == 0 {
+	if epXdata0Out[ep] || ep == 0 {
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlData1Pid)
 	}
 
 	_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
 }
 
+// Set the USB endpoint Packet ID to DATA0 or DATA1 for IN direction.
+func setEPDataPIDIn(ep uint32, dataOne bool) {
+	epXdata0In[ep] = dataOne
+	if epXdata0In[ep] || ep == 0 {
+		_usbDPSRAM.EPxBufferControl[ep].In.SetBits(usbBuf0CtrlData1Pid)
+	}
+
+	_usbDPSRAM.EPxBufferControl[ep].In.SetBits(usbBuf0CtrlAvail)
+}
+
 func SendZlp() {
 	sendUSBPacket(0, nil)
 }
@@ -138,15 +166,19 @@ func sendViaEPIn(ep uint32, data []byte, count int) {
 	val := uint32(count) | usbBuf0CtrlAvail
 
 	// DATA0 or DATA1
-	epXdata0[ep&0x7F] = !epXdata0[ep&0x7F]
+	epXdata0In[ep&0x7F] = !epXdata0In[ep&0x7F]
-	if !epXdata0[ep&0x7F] {
+	if !epXdata0In[ep&0x7F] {
 		val |= usbBuf0CtrlData1Pid
 	}
 
 	// Mark as full
 	val |= usbBuf0CtrlFull
 
-	copy(_usbDPSRAM.EPxBuffer[ep&0x7F].Buffer0[:], data[:count])
+	if (ep & 0x7F) == 0 {
+		copy(_usbDPSRAM.EPxBuffer[0].Buffer0[:], data[:count])
+	} else {
+		copy(_usbDPSRAM.EPxBuffer[ep&0x7F].Buffer1[:], data[:count])
+	}
 	_usbDPSRAM.EPxBufferControl[ep&0x7F].In.Set(val)
 }
 
@@ -178,9 +210,9 @@ func (dev *USBDevice) ClearStallEPIn(ep uint32) {
 	ep = ep & 0x7F
 	val := uint32(usbBuf0CtrlStall)
 	_usbDPSRAM.EPxBufferControl[ep].In.ClearBits(val)
-	if epXPIDReset[ep] {
+	if epXPIDResetIn[ep] {
 		// Reset the PID to DATA0
-		setEPDataPID(ep, false)
+		setEPDataPIDIn(ep, false)
 	}
 }
 
@@ -189,9 +221,9 @@ func (dev *USBDevice) ClearStallEPOut(ep uint32) {
 	ep = ep & 0x7F
 	val := uint32(usbBuf0CtrlStall)
 	_usbDPSRAM.EPxBufferControl[ep].Out.ClearBits(val)
-	if epXPIDReset[ep] {
+	if epXPIDResetOut[ep] {
 		// Reset the PID to DATA0
-		setEPDataPID(ep, false)
+		setEPDataPIDOut(ep, false)
 	}
 }
 
@@ -219,10 +251,12 @@ type usbBuffer struct {
 }
 
 var (
-	_usbDPSRAM  = (*usbDPSRAM)(unsafe.Pointer(uintptr(0x50100000)))
+	_usbDPSRAM     = (*usbDPSRAM)(unsafe.Pointer(uintptr(0x50100000)))
-	epXdata0    [16]bool
+	epXdata0In     [16]bool
-	epXPIDReset [16]bool
+	epXdata0Out    [16]bool
-	setupBytes  [8]byte
+	epXPIDResetIn  [16]bool
+	epXPIDResetOut [16]bool
+	setupBytes     [8]byte
 )
 
 func (d *usbDPSRAM) setupBytes() []byte {

src/machine/usb/cdc/cdc.go

@@ -2,10 +2,14 @@
 
 package cdc
 
+import (
+	"machine/usb"
+)
+
 const (
-	cdcEndpointACM = 1
+	cdcEndpointACM = usb.CDC_ENDPOINT_ACM
-	cdcEndpointOut = 2
+	cdcEndpointOut = usb.CDC_ENDPOINT_OUT
-	cdcEndpointIn  = 3
+	cdcEndpointIn  = usb.CDC_ENDPOINT_IN
 )
 
 // New returns USBCDC struct.

src/machine/usb/msc/msc.go

@@ -166,6 +166,7 @@ func (m *msc) sendCSW(status csw.Status) {
 	}
 	m.cbw.CSW(status, residue, m.cswBuf)
 	m.state = mscStateStatusSent
+	m.queuedBytes = csw.MsgLen
 	m.sendUSBPacket(m.cswBuf)
 }
 
@@ -235,9 +236,9 @@ func (m *msc) run(b []byte, isEpOut bool) bool {
 			// 6.6.1 CBW Not Valid
 			// https://usb.org/sites/default/files/usbmassbulk_10.pdf
 			m.state = mscStateNeedReset
-			m.stallEndpoint(usb.MSC_ENDPOINT_IN)
+			m.stallEndpointIn(usb.MSC_ENDPOINT_IN)
-			m.stallEndpoint(usb.MSC_ENDPOINT_OUT)
+			m.stallEndpointOut(usb.MSC_ENDPOINT_OUT)
-			m.stallEndpoint(usb.CONTROL_ENDPOINT)
+			m.stallEndpointIn(usb.CONTROL_ENDPOINT)
 			return ack
 		}
 
@@ -284,7 +285,7 @@ func (m *msc) run(b []byte, isEpOut bool) bool {
 	if m.state == mscStateStatus && !m.txStalled {
 		if m.cbw.transferLength() > m.sentBytes && m.cbw.isIn() {
 			// 6.7.2 The Thirteen Cases - Case 5 (Hi > Di): STALL before status
-			m.stallEndpoint(usb.MSC_ENDPOINT_IN)
+			m.stallEndpointIn(usb.MSC_ENDPOINT_IN)
 		} else if m.sendZLP {
 			// Send a zero-length packet to force the end of the transfer before we send a CSW
 			m.queuedBytes = 0

src/machine/usb/msc/scsi.go

@@ -298,9 +298,9 @@ func (m *msc) sendScsiError(status csw.Status, key scsi.Sense, code scsi.SenseCo
 
 	if expected > 0 && residue > 0 {
 		if m.cbw.isIn() {
-			m.stallEndpoint(usb.MSC_ENDPOINT_IN)
+			m.stallEndpointIn(usb.MSC_ENDPOINT_IN)
 		} else {
-			m.stallEndpoint(usb.MSC_ENDPOINT_OUT)
+			m.stallEndpointOut(usb.MSC_ENDPOINT_OUT)
 		}
 	}
 }

src/machine/usb/msc/setup.go

@@ -52,32 +52,30 @@ func (m *msc) handleClearFeature(setup usb.Setup, wValue uint16) bool {
 	// (c) a Clear Feature HALT to the Bulk-Out endpoint (clear stall OUT)
 	// https://usb.org/sites/default/files/usbmassbulk_10.pdf
 	if m.state == mscStateNeedReset {
-		wIndex := setup.WIndex & 0x7F // Clear the direction bit from the endpoint address for comparison
+		wIndex := uint8(setup.WIndex & 0x7F)
 		if wIndex == usb.MSC_ENDPOINT_IN {
-			m.stallEndpoint(usb.MSC_ENDPOINT_IN)
+			if (setup.WIndex & 0x80) != 0 {
-		} else if wIndex == usb.MSC_ENDPOINT_OUT {
+				m.stallEndpointIn(wIndex)
-			m.stallEndpoint(usb.MSC_ENDPOINT_OUT)
+			} else {
+				m.stallEndpointOut(wIndex)
+			}
 		}
 		machine.SendZlp()
 		return true
 	}
 
-	// Clear the direction bit from the endpoint address for comparison
+	wIndex := uint8(setup.WIndex & 0x7F)
-	wIndex := setup.WIndex & 0x7F
-
-	// Clear the IN/OUT stalls if addressed to the endpoint
 	if wIndex == usb.MSC_ENDPOINT_IN {
-		m.clearStallEndpoint(usb.MSC_ENDPOINT_IN)
+		if (setup.WIndex & 0x80) != 0 {
-		ok = true
+			m.clearStallEndpointIn(wIndex)
-	}
+			ok = true
-	if wIndex == usb.MSC_ENDPOINT_OUT {
+			if m.state == mscStateStatus {
-		m.clearStallEndpoint(usb.MSC_ENDPOINT_OUT)
+				m.sendCSW(m.respStatus)
-		ok = true
+			}
-	}
+		} else {
-	// Send a CSW if needed to resume after the IN endpoint stall is cleared
+			m.clearStallEndpointOut(wIndex)
-	if m.state == mscStateStatus && wIndex == usb.MSC_ENDPOINT_IN {
+			ok = true
-		m.sendCSW(m.respStatus)
+		}
-		ok = true
 	}
 
 	if ok {
@@ -120,26 +118,28 @@ func (m *msc) handleReset(setup usb.Setup, wValue uint16) bool {
 	return true
 }
 
-func (m *msc) stallEndpoint(ep uint8) {
+func (m *msc) stallEndpointIn(ep uint8) {
-	if ep == usb.MSC_ENDPOINT_IN {
+	if ep == usb.CONTROL_ENDPOINT {
-		m.txStalled = true
-		machine.USBDev.SetStallEPIn(usb.MSC_ENDPOINT_IN)
-	} else if ep == usb.MSC_ENDPOINT_OUT {
-		m.rxStalled = true
-		machine.USBDev.SetStallEPOut(usb.MSC_ENDPOINT_OUT)
-	} else if ep == usb.CONTROL_ENDPOINT {
 		machine.USBDev.SetStallEPIn(usb.CONTROL_ENDPOINT)
+		return
 	}
+	m.txStalled = true
+	machine.USBDev.SetStallEPIn(uint32(ep))
 }
 
-func (m *msc) clearStallEndpoint(ep uint8) {
+func (m *msc) stallEndpointOut(ep uint8) {
-	if ep == usb.MSC_ENDPOINT_IN {
+	m.rxStalled = true
-		machine.USBDev.ClearStallEPIn(usb.MSC_ENDPOINT_IN)
+	machine.USBDev.SetStallEPOut(uint32(ep))
-		m.txStalled = false
+}
-	} else if ep == usb.MSC_ENDPOINT_OUT {
+
-		machine.USBDev.ClearStallEPOut(usb.MSC_ENDPOINT_OUT)
+func (m *msc) clearStallEndpointIn(ep uint8) {
-		m.rxStalled = false
+	machine.USBDev.ClearStallEPIn(uint32(ep))
-	}
+	m.txStalled = false
+}
+
+func (m *msc) clearStallEndpointOut(ep uint8) {
+	machine.USBDev.ClearStallEPOut(uint32(ep))
+	m.rxStalled = false
 }
 
 func (m *msc) setStringField(field []byte, value string) {