Create atomic instructions.

[Labdabeta]

Currently creating a mutex between units is very cumbersome. Many commands don't use all their arguments. It should be possible to either augment an existing command or replace one to produce something like a test and set instruction.

[Cluedrew]

Until individual units get multiple processes, there is not point to have a "for me" atomic instruction. Instead they have to be for communication. Of the two main areas for communication: Team chat is viable and since there is one it is easy to target it.

Unit chats are harder on the captain's side, as it doesn't have space for another 10 instructions. The other solution is to overhaul the write commands. C = unit[B]; unit[B] = A When C is r0 (or any read only register) the command mostly acts as before. Mostly in that we now have a smaller I value to specify the address to write to, but you can use a register to get around that. Still it breaks symmetry with the read and makes non-atomic usage a bit more inconvenient.

Depending on how the game goes forcing some communication to team memory (vulnerable to HAK and EMP) might actually be a bonus. At the current point, creating a mutex is actually very unnecessary.

[Cluedrew]

By the way, I have thought a bit about this one and I realized you can create "atomic" instructions if you are willing to have an extra unit be a supervisor.

You have to set aside two memory addresses: the lock and the request slot. The lock is 0 when open and when held is the holder's unit id. Only the holder or the supervisor may write to the lock. The request slot is where other units write their unit id when they would like to acquire the lock. The supervisor, every once in a while, checks the lock and if it is 0, writes the value of the request slot there. If the value there was non-zero, that unit now has the lock (the request slot should be cleared, either the holder or supervisor can do it).

A unit does have to check to see when and if it got the lock, and depending on how often the supervisor checks the lock acquire operations can take a while, but I have as of yet been unable to figure out a way for multiple people to have, or think they have, the lock as long as the protocol is followed.