Exploring some more advanced verification constructs

The testing we have done thus far has been pretty simple, even when we used self-checking. There is one construct that I have found very useful over the years. The queue is easy to use and understand.

Introducing SystemVerilog queues

Often, you need to generate an input in a design that will produce an expected output sometime later. Examples of this are parsing engines, data processing engines, and, as we saw in Chapter 10, A Better Way to Display – VGA, the PS/2 interface.

When I modified the ps2_host module, I decided to upgrade the testbench for it using queues. I had to create a structure to define what I wanted to store in the queue:

typedef struct packed
  {
   logic [7:0] data;
   logic       parity;
  } ps2_rx_data_t;

This structure will store our expected data as we generate data in the ps2_host for testing.

A queue is defined as follows:

ps2_rx_data_t ps2_rx_data[$];

It looks much...