MulticastRoutingTableByPartitionEntry needs a Spin2 version

[Christian-B]

MulticastRoutingTableByPartitionEntry its spinnaker_route uses 5 bits for processor id.

It appears that the first 8 ant last 8 bits are used.
3 for link and 5 for processors.

5 bits are not enough for all the spin cores.

===

For spin2 we will need to decide if the cores are virtual or 2d addresses

[rowleya]

I thought the actual bits were part of SpiNNMachine. Maybe this should be the case if it isn't already...

[Christian-B]

There are hard coded n_cores, shifts and masks
see

PACMAN/pacman/model/routing_table_by_partition/multicast_routing_table_by_partition_entry.py

Line 23 in 07ec798

_INCOMING_LINK_MASK = 0x07000000

The big issue is that many changes here(python side) need matching changes C side

[Christian-B]

If this is PACMAN or SpiNNMachine is the least of the worries here

[rowleya]

It is more a case of having lots of different places that do the same thing. In some ways, it would be useful for PACMAN to "not care" about the details of SpiNNaker bits, and just ask SpiNNMachine to do it. There is a MulticastRoutingEntry in SpiNNMachine, so maybe this is a better place to do conversions?

In terms of things happening in C, only SCAMP / SARK would need to be different. Nowhere else should care...

[Christian-B]

The relationship between Pacman's MulticastRoutingTableByPartitionEntry and SpinnMachine's MulticastRoutingEntry does need reviewing.

Why have 2 and why does the PACMAN one have and need incoming info.

[Christian-B]

fixed by #550