system-verilog

There are different data types in systemverilog that can be used like the following: reg [31:0] data; logic [31:0] data; bit [31:0] data; How does the three of them differ? reg and wire were the original types. Wires are constantly assigned and regs are evaluated at particular points, the advantage here is for the simulator to make optimisations. wire w_data; assign w_data = y; // Same function as above using reg reg r_data; always @* r_data = y ; A common mistake when learning Verilog is to assume the a reg type implies a register in hardware. The earlier optimisation for the simulator can be

Looking at some code I'm maintaining in System Verilog I see some signals that are defined like this: node [range_hi:range_lo]x; and others that are defined like this: node y[range_hi:range_lo]; I understand that x is defined as packed, while y is defined as unpacked. However, I have no idea what that means. What is the difference between packed and unpacked vectors in System Verilog? Edit: Responding to @Empi's answer, why should a hardware designer who's writing in SV care about the internal representation of the array? Are there any times when I shouldn't or can't use packed signals? This

If I have a Verilog module 'top' and a verilog module 'subcomponent' how do I instantiate subcomponent in top? top: module top( input clk, input rst_n, input enable, input [9:0] data_rx_1, input [9:0] data_rx_2, output [9:0] data_tx_2 ); subcomponent: module subcomponent( input clk, input rst_n, input [9:0] data_rx, output [9:0] data_tx ); Note This was written as a generic question that keeps cropping up now and again, it is following the self-answer format. Addition answers and updates are encouraged. This is all generally covered by Section 23.3.2 of SystemVerilog IEEE Std 1800-2012 . The

I've recently saw this operator in a verilog/systemverilog code. logic [15:0] down_vect; logic [0:15] up_vect; down_vect[lsb_base_expr +: width_expr] up_vect [msb_base_expr +: width_expr] down_vect[msb_base_expr -: width_expr] up_vect [lsb_base_expr -: width_expr] I've rarely seen this so, I'd like to ask What is this, When and How do you use it? That particular syntax is called an indexed part select . It's very useful when you need to select a fixed number of bits from a variable offset within a multi-bit register. Here's an example of the syntax: reg [31:0] dword; reg [7:0] byte0; reg [7:0]

I am a little confused about how blocking and non blocking assignments are interpreted when it comes to drawing a hardware diagram. Do we have to infer that a non blocking assignment gives us a register? Then according to this statement c <= a+b , c would be a register right, but not a and b? module add (input logic clock, output logic[7:0] f); logic[7:0] a, b, c; always_ff @(posedge clock) begin a = b + c; b = c + a; c <= a + b; end assign f = c; endmodule Marty It's definitely a bit tricky to get your head around the differences between blocking and nonblocking assignments initially. But no