Added "bytes awaiting write" functionality

src/main/c/Android/jni/com_fazecast_jSerialComm_SerialPort.h

@@ -143,6 +143,14 @@ JNIEXPORT jint JNICALL Java_com_fazecast_jSerialComm_SerialPort_waitForEvent
 JNIEXPORT jint JNICALL Java_com_fazecast_jSerialComm_SerialPort_bytesAvailable
   (JNIEnv *, jobject, jlong);
 
+/*
+ * Class:     com_fazecast_jSerialComm_SerialPort
+ * Method:    bytesAwaitingWrite
+ * Signature: (J)I
+ */
+JNIEXPORT jint JNICALL Java_com_fazecast_jSerialComm_SerialPort_bytesAwaitingWrite
+  (JNIEnv *, jobject, jlong);
+
 /*
  * Class:     com_fazecast_jSerialComm_SerialPort
  * Method:    readBytes

src/main/c/OSX/SerialPort_OSX.c

@@ -378,6 +378,15 @@ JNIEXPORT jint JNICALL Java_com_fazecast_jSerialComm_SerialPort_bytesAvailable(J
 	return numBytesAvailable;
 }
 
+JNIEXPORT jint JNICALL Java_com_fazecast_jSerialComm_SerialPort_bytesAwaitingWrite(JNIEnv *env, jobject obj, jlong serialPortFD)
+{
+	int numBytesToWrite = -1;
+	if (serialPortFD > 0)
+		ioctl(serialPortFD, TIOCOUTQ, &numBytesToWrite);
+
+	return numBytesToWrite;
+}
+
 JNIEXPORT jint JNICALL Java_com_fazecast_jSerialComm_SerialPort_readBytes(JNIEnv *env, jobject obj, jlong serialPortFD, jbyteArray buffer, jlong bytesToRead)
 {
 	// Get port handle and read timeout from Java class