I am trying to add another custom Execution Unit in T1. What I have observed from instruction on the Multiplier path is:
1. Datapath is the simplest. Just forward the RS1 and RS2 to new execution unit and the result can be fowarded the bypass unit in EXU.
2. Controlpath - New opcode needs to be added on IFU_DEC unit and select signals to be forwarded execution control logic unit, which forwards to the execution unit
3. some control signals need to be send to IFU_Switch unit to switch out that thread when the Execution Unit is busy. also to rollback the second instruction to the new custom EXU at IFU_Switch.
4. Also a done signal from the custom EXU to execution control logic and IFU_Switch.