Coding Review

Useful Operators

The tertiary operator allows for a one line if-else value assignment. assign a = (condition) ? true_value : else_value;

Always

Use always_comb for combinational logic in RTL and always_ff for sequential logic in RTL. With always_comb, you would set a equal to b with a = b. The value assignment would be instantaneous (as it is combinational).

With always_ff, one would assign with a <= b which helps to indicate that the change is not instantaneous but rather after a clock cycle.

XPROP

Use `ECE2300_SEQ_XPROP(value, $isunknown(conditional_on)); for X-propagation handling. Think carefully about the conditions where an unknown value should trigger another value to be an x.

RTL Flip Flops

always_ff @(posedge clk) begin
    q <= d;
end

With reset:

always_ff @(posedge clk) begin
    q <= (d & !rst);
end

With reset and enable:

always_ff @(posedge clk) begin
    if (rst)
        q <= 1'b0;
    else if (en)
        q <= d;
    `ECE2300_SEQ_XPROP(q, $isunknown(rst));
    `ECE2300_SEQ_XPROP(q, (rst == 0) && $isunknown(en));
end