Merge branch 'fix/magic-numbers': extract magic numbers to named constants (review 4.3)

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

@@ -43,6 +43,9 @@ class MainActivity : AppCompatActivity() {
         private const val HMAC_LEN = 32
         private const val REQUEST_SETTINGS = 1
         private const val SCAN_TIMEOUT_MS = 10000L
+        private const val RECONNECT_DELAY_MS = 2000L
+        private const val POST_SETTINGS_RESCAN_MS = 500L
+        private const val ON_RESUME_SCAN_DELAY_MS = 300L
     }
 
     private var bluetoothGatt: BluetoothGatt? = null
@@ -92,7 +95,7 @@ class MainActivity : AppCompatActivity() {
                 bluetoothGatt = null
                 relayCharacteristic = null
                 seq = 1
-                handler.postDelayed(scanRunnable, 2000)
+                handler.postDelayed(scanRunnable, RECONNECT_DELAY_MS)
             }
         }
 
@@ -170,7 +173,7 @@ class MainActivity : AppCompatActivity() {
             relayCharacteristic = null
             seq = 1
             loadState()
-            handler.postDelayed(scanRunnable, 500)
+            handler.postDelayed(scanRunnable, POST_SETTINGS_RESCAN_MS)
         }
     }
 
@@ -186,7 +189,7 @@ class MainActivity : AppCompatActivity() {
         if (hmacKey == null) {
             statusText.text = getString(R.string.status_no_key)
         } else if (!isScanning && bluetoothGatt == null) {
-            handler.postDelayed(scanRunnable, 300)
+            handler.postDelayed(scanRunnable, ON_RESUME_SCAN_DELAY_MS)
         }
     }
 

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

@@ -44,6 +44,9 @@ class SettingsActivity : AppCompatActivity() {
         private const val KEY_SETTLE_MS = 1000L
         private const val RESPONSE_WAIT_MS = 500L
         private const val USB_BULK_TIMEOUT_MS = 1000
+        private const val FLUSH_TIMEOUT_MS = 100
+        private const val READ_CHUNK_TIMEOUT_MS = 500
+        private const val CDC_CONTROL_TIMEOUT_MS = 500
         private const val ACTION_USB_PERMISSION = "com.eddy.atomrelay.USB_PERMISSION"
         private const val STYLE_SPINNER = 0
         private const val STYLE_HORIZONTAL = 1
@@ -472,7 +475,7 @@ class SettingsActivity : AppCompatActivity() {
     private fun flushReadBuffer(connection: UsbDeviceConnection, epIn: UsbEndpoint) {
         val buf = ByteArray(512)
         while (true) {
-            val len = connection.bulkTransfer(epIn, buf, buf.size, 100)
+            val len = connection.bulkTransfer(epIn, buf, buf.size, FLUSH_TIMEOUT_MS)
             if (len <= 0) break
             Log.d(TAG, "Flushed $len bytes from read buffer")
         }
@@ -484,7 +487,7 @@ class SettingsActivity : AppCompatActivity() {
         val startTime = System.currentTimeMillis()
 
         while (System.currentTimeMillis() - startTime < timeoutMs) {
-            val len = connection.bulkTransfer(epIn, buf, buf.size, 500)
+            val len = connection.bulkTransfer(epIn, buf, buf.size, READ_CHUNK_TIMEOUT_MS)
             if (len > 0) {
                 sb.append(String(buf, 0, len, StandardCharsets.US_ASCII))
                 if ((sb.contains("HMAC_KEY:") || sb.contains("NO_KEY") || sb.contains("OK")) && sb.contains("\n")) {
@@ -506,8 +509,24 @@ class SettingsActivity : AppCompatActivity() {
                 0x00.toByte(), 0xC2.toByte(), 0x01.toByte(), 0x00.toByte(),
                 0x00.toByte(), 0x00.toByte(), 0x08.toByte()
             )
-            connection.controlTransfer(0x21, 0x20, 0, ctrlIntf.id, lineCoding, lineCoding.size, 500)
+            connection.controlTransfer(
-            connection.controlTransfer(0x21, 0x22, 3, ctrlIntf.id, null, 0, 500)
+                UsbUtils.CDC_REQUEST_TYPE,
+                UsbUtils.CDC_SET_LINE_CODING,
+                0,
+                ctrlIntf.id,
+                lineCoding,
+                lineCoding.size,
+                CDC_CONTROL_TIMEOUT_MS
+            )
+            connection.controlTransfer(
+                UsbUtils.CDC_REQUEST_TYPE,
+                UsbUtils.CDC_SET_CONTROL_LINE_STATE,
+                UsbUtils.CDC_DTR or UsbUtils.CDC_RTS,
+                ctrlIntf.id,
+                null,
+                0,
+                CDC_CONTROL_TIMEOUT_MS
+            )
             Log.d(TAG, "CDC control interface configured")
         } else {
             Log.w(TAG, "No CDC control interface found, trying without")

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

@@ -15,6 +15,7 @@ class UsbSerialTransport(
 
     companion object {
         private const val USB_TIMEOUT_MS = 5000
+        private const val CONTROL_LINE_TIMEOUT_MS = 1000
     }
 
     override fun read(buffer: ByteArray, length: Int): Int {
@@ -31,12 +32,12 @@ class UsbSerialTransport(
     override fun setControlLines(dtr: Boolean, rts: Boolean) {
         connection.controlTransfer(
             UsbConstants.USB_DIR_OUT or UsbConstants.USB_TYPE_CLASS or 0x01,
-            0x22,
+            UsbUtils.CDC_SET_CONTROL_LINE_STATE,
-            (if (dtr) 0x01 else 0x00) or (if (rts) 0x02 else 0x00),
+            (if (dtr) UsbUtils.CDC_DTR else 0x00) or (if (rts) UsbUtils.CDC_RTS else 0x00),
             0,
             null,
             0,
-            1000
+            CONTROL_LINE_TIMEOUT_MS
         )
     }
 

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

@@ -9,6 +9,13 @@ import android.hardware.usb.UsbInterface
 object UsbUtils {
     private const val CDC_DATA_INTERFACE_CLASS = 0x0A
 
+    // CDC-ACM class-specific control request constants (USB CDC 1.20 spec)
+    const val CDC_REQUEST_TYPE = 0x21
+    const val CDC_SET_LINE_CODING = 0x20
+    const val CDC_SET_CONTROL_LINE_STATE = 0x22
+    const val CDC_DTR = 0x01
+    const val CDC_RTS = 0x02
+
     fun findCdcDataInterface(device: UsbDevice): UsbInterface? {
         for (i in 0 until device.interfaceCount) {
             val intf = device.getInterface(i)
@@ -28,4 +35,4 @@ object UsbUtils {
         }
         return null
     }
-}
+}