OpenPiton Transducer in WARP-V

[shivampotdar]

Integration of WARP-V with OpenPiton

Google Summer of Code 2020 Project with FOSSi Foundation

-- Shivam Potdar, India

This PR aims to add support for integrating WARP-V with Bring Your Own Core (BYOC) (A fork of OpenPiton from Princeton University)
(This one is pending for merge while other parts of the project are already upstream)

The following changes are made :

• Other cores which are supported in BYOC have a separate transducer module which instantiated alongside the core. With WARP-V and the flexibility that is possible, we can generate one top-level module (warpv_openpiton) to directly contain all the interface signals with the BYOC Transaction-Response Interface (TRI).
• Both decoding the encoding logic for the TRI signals is internal to the core
• To support memory requests with variable latency, a generic external memory interface is in progress, which would eliminate the internal instruction and data memory conditionally.