signalVector: Implement segment().

Change-Id: I6fe3aae53fb2fa5bb7637e976de6059eabe08202

Transceiver52M/signalVector.cpp

@@ -45,6 +45,11 @@ void signalVector::operator=(const signalVector& vector)
 	mStart = mData + vector.getStart();
 }
 
+signalVector signalVector::segment(size_t start, size_t span)
+{
+	return signalVector(mData, start, span);
+}
+
 size_t signalVector::getStart() const
 {
 	return mStart - mData;

Transceiver52M/signalVector.h

@@ -30,6 +30,9 @@ public:
 	/** Override base assignment operator to include start offsets */
 	void operator=(const signalVector& vector);
 
+	/** Return an alias to a segment of this signalVector. */
+	signalVector segment(size_t start, size_t span);
+
 	/** Return head room */
 	size_t getStart() const;
 	size_t updateHistory();