Add UsbUtils utility object for shared USB functions

android/app/src/main/java/com/eddy/atomrelay/UsbUtils.kt

@@ -0,0 +1,30 @@
+package com.eddy.atomrelay
+
+import android.hardware.usb.UsbConstants
+import android.hardware.usb.UsbDevice
+import android.hardware.usb.UsbEndpoint
+import android.hardware.usb.UsbInterface
+
+object UsbUtils {
+    private const val CDC_DATA_INTERFACE_CLASS = 0x0A
+
+    fun findCdcDataInterface(device: UsbDevice): UsbInterface? {
+        for (i in 0 until device.interfaceCount) {
+            val intf = device.getInterface(i)
+            if (intf.interfaceClass == CDC_DATA_INTERFACE_CLASS) {
+                return intf
+            }
+        }
+        return null
+    }
+
+    fun findBulkEndpoint(intf: UsbInterface, direction: Int): UsbEndpoint? {
+        for (i in 0 until intf.endpointCount) {
+            val ep = intf.getEndpoint(i)
+            if (ep.type == UsbConstants.USB_ENDPOINT_XFER_BULK && ep.direction == direction) {
+                return ep
+            }
+        }
+        return null
+    }
+}