Transceiver52M: Set resampling option automatically based on device

Remove the built time resampling selection and link both options.
Move the normal push/pullBuffer() calls back to the base class and
overload them in the inherited resampling class.

USRP2/N2xx devices are the only devices that require resampling so
return that resampling is necessary on the device open(), which is
the point at which the device type will be known.

The GSM transceiver only operates at a whole number multiple of
the GSM rate and doesn't care about the actual device rate and
if resampling is used. Therefore GSM specific portion of the
transceiver should only need to submit the samples-per-symbol
value to the device interface.

Then, the device should be able to determine the appropriate
sample rate (400 ksps or 270.833 ksps) and if resampling is
appropriate.

Signed-off-by: Thomas Tsou <tom@tsou.cc>
diff --git a/Transceiver52M/radioDevice.h b/Transceiver52M/radioDevice.h
index ff3421c..485d037 100644
--- a/Transceiver52M/radioDevice.h
+++ b/Transceiver52M/radioDevice.h
@@ -21,6 +21,8 @@
 #include "config.h"
 #endif
 
+#define GSMRATE       1625e3/6
+
 /** a 64-bit virtual timestamp for radio data */
 typedef unsigned long long TIMESTAMP;
 
@@ -31,10 +33,13 @@
   /* Available transport bus types */
   enum TxWindowType { TX_WINDOW_USRP1, TX_WINDOW_FIXED };
 
-  static RadioDevice *make(double desiredSampleRate, int sps, bool skipRx = false);
+  /* Radio interface types */
+  enum RadioInterfaceType { NORMAL, RESAMP };
+
+  static RadioDevice *make(int sps, bool skipRx = false);
 
   /** Initialize the USRP */
-  virtual bool open(const std::string &args)=0;
+  virtual int open(const std::string &args)=0;
 
   /** Start the USRP */
   virtual bool start()=0;