partition: p p p (3 bits)
out : AAA3 AAA2 AAA1 AAA0 BBB3 BBB2 BBB1 BBB0 (64 bits)
-When 2x16:
+When 2x16, the top 2 halves of A and B are Catted together,
+and likewise the lower:
+ partition: p p p (3 bits)
+ out : AAA3 AAA2 BBB3 BBB2 AAA1 AAA0 BBB1 BBB0 (64 bits)
+
+Finally when 4x8, each byte is concatenated:
+
+ partition: p p p (3 bits)
+ out : AAA3 BBB3 AAA2 BBB2 AAA1 BBB1 AAA0 BBB0 (64 bits)
+
+This then generalises regardless of the number of PartitionedSignals
+being Concatenated, and, also, regardless of the actual length of
+each individual PartitionedSignal.
+
+To confirm that et us assume that A is 16-bit and B is 32-bit: