Transceiver52M: sigproc: Wrap internal phase on frequency shift

The call into table lookup will loop on values outside of the
table range. With continuously increasing phase, this leads
to an eventual permanent hard spin. Wrap the phase value to
prevent that from happening.

Signed-off-by: Thomas Tsou <tom@tsou.cc>

Transceiver52M/sigProcLib.cpp

@@ -613,6 +613,10 @@ signalVector* frequencyShift(signalVector *y,
     while (xP < xPEnd) {
       (*yP++) = (*xP++)*expjLookup(phase);
       phase += freq;
+      if (phase > 2 * M_PI)
+        phase -= 2 * M_PI;
+      else if (phase < -2 * M_PI)
+        phase += 2 * M_PI;
     }
   }