Topology Port Export Spec

[Kronos3]

My initial pass at a spec for exporting topology ports.

TODO:

• Update wiki

Closes #744

[Kronos3]

Some open questions for @bocchino

• Currently this spec states that you must import a topology to be able to connect to ports exported from the topology. Thinking ahead to sub-topologies, I'm not sure if this is right. I think that composing topologies should potentially be done another way:

Without re-usable sub-topologies

topology T1 {
 instance i

 export i.p[0] as schedIn
}

topology T2 {
  # Not sure of an exact syntax, but something to denote that we are bringing in a topology without doing a full white-box import
  topology T1   
}

With re-usable subtopologies

topology T1(constant baseId) {
  instance i1: Component base id baseId + 0
  instance i2: Component base id baseId + 0x20

  connections {
    # ... internal connections ...
  }

  export i1.port as externalPort1
  export i2.port as externalPort2
}

topology T2 {
  topology t1 = T1(0xA)
  topology t2 = T1(0xB)

  connections {
    t1.externalPort1 -> t2.externalPort2
  }
}