Hidden Wires

Description

SystemVerilog proof-of-concept for using static variables inside functions to communicate between modules.

This allows connections to be made without having to add wiring through the hierarchy. Possible applications include pulling signals out to logic analyser, writing to global resources (event log, statistics, UART etc.)

This project compiles and does the "right thing" in Quartus. Unfortunately Xilinx do not yet support static functions (see this thread for further detail).

Diagram

       +-------------------------------------------+
       |  top                                      |
       +-------------------------------------------+
       |                                           |
       |     +---------+           +---------+     |
       |     | module1 |           | module2 |     |
       |     |---------|           |---------|     |
       |     |         |           |         |     |
     +------->         |           |         +------->
     +------->         |           |         +------->
     +------->         |           |         +------->
       |     |         |           |         |     |
       |  +----(set=1) |           | (set=0)----+  |
       |  |  |         |           |         |  |  |
       |  |  +---------+           +---------+  |  |
       |  |                                     |  |
       |  |                                     |  |
       |  |                                     |  |
       |  |    +---------------------------+    |  |
       |  |    | hidden_wires_pkg::connect |    |  |
       |  |    |---------------------------|    |  |
       |  |    | static variable           |    |  |
       |  +--->|                           |<---+  |
       |       |                           |       |
       |       +---------------------------+       |
       |                                           |
       +-------------------------------------------+