means that the memory block is used to store the sorted
v-to-c messages derived for layer in iteration . In addition,
if there is “PC I” or “PC II” on a bar, it represents that the Path
Constructor I or II is reading from that memory block. During
the sorting for each layer, the two shaded RAM E blocks are
used in a ping-pong manner for storing intermediate results.
The absence of bars translates to that the computation unit or
memory is not required for any computation or data storage
during that time.