chore: make names more consistent

Author: mikesmitty

src/machine/machine_rp2_usb.go

@@ -83,7 +83,7 @@ func sendUSBPacket(ep uint32, data []byte, maxsize uint16) {
 		} else {
 			sendOnEP0DATADONE.offset = 0
 		}
-		inEpXdata0[ep] = true
+		inEpXdata0[ep] = usbPIDData1
 	}
 
 	sendViaEPIn(ep, data, count)
@@ -120,11 +120,11 @@ func handleEndpointRx(ep uint32) []byte {
 // AckUsbOutTransfer is called to acknowledge the completion of a USB OUT transfer.
 func AckUsbOutTransfer(ep uint32) {
 	ep = ep & 0x7F
-	setEPOutDataPID(ep, !outEpXdata0[ep])
+	setOutEPDataPID(ep, !outEpXdata0[ep])
 }
 
 // Set the USB endpoint Packet ID to DATA0 or DATA1.
-func setEPInDataPID(ep uint32, dataOne bool) {
+func setInEPDataPID(ep uint32, dataOne usbPID) {
 	ep = ep & 0x7F
 	inEpXdata0[ep] = dataOne
 	if inEpXdata0[ep] || ep == 0 {
@@ -135,7 +135,7 @@ func setEPInDataPID(ep uint32, dataOne bool) {
 }
 
 // Set the USB endpoint Packet ID to DATA0 or DATA1.
-func setEPOutDataPID(ep uint32, dataOne bool) {
+func setOutEPDataPID(ep uint32, dataOne usbPID) {
 	outEpXdata0[ep] = dataOne
 	if outEpXdata0[ep] || ep == 0 {
 		_usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlData1Pid)
@@ -197,7 +197,7 @@ func (dev *USBDevice) ClearStallEPIn(ep uint32) {
 	_usbDPSRAM.EPxBufferControl[ep].In.ClearBits(val)
 	if inEpXPIDReset[ep] {
 		// Reset the PID to DATA0
-		setEPInDataPID(ep, false)
+		setInEPDataPID(ep, usbPIDData0)
 	}
 }
 
@@ -208,7 +208,7 @@ func (dev *USBDevice) ClearStallEPOut(ep uint32) {
 	_usbDPSRAM.EPxBufferControl[ep].Out.ClearBits(val)
 	if outEpXPIDReset[ep] {
 		// Reset the PID to DATA0
-		setEPOutDataPID(ep, false)
+		setOutEPDataPID(ep, usbPIDData0)
 	}
 }
 
@@ -237,10 +237,18 @@ type usbBuffer struct {
 	Buffer1 [usbBufferLen]byte
 }
 
+// USB Packet ID
+type usbPID bool
+
+const (
+	usbPIDData0 usbPID = false
+	usbPIDData1 usbPID = true
+)
+
 var (
 	_usbDPSRAM     = (*usbDPSRAM)(unsafe.Pointer(uintptr(0x50100000)))
-	inEpXdata0     [16]bool
-	outEpXdata0    [16]bool
+	inEpXdata0     [16]usbPID
+	outEpXdata0    [16]usbPID
 	inEpXPIDReset  [16]bool
 	outEpXPIDReset [16]bool
 	setupBytes     [8]byte