Verilog parallel block implementation

Parallel blocks

Parallel blocks have keywords fork and join To express .

Statements in parallel blocks are executed in parallel , Even blocking assignments .

The delay of each statement in a parallel block is related to the time when the block statement begins to execute .

The difference between sequential blocks and parallel blocks is obvious , Let's use simulation to illustrate .

The simulation code is as follows :

example

`timescale 1ns/1ns
 
module test ;
    reg [3:0]   ai_sequen, bi_sequen ;
    reg [3:0]   ai_paral,  bi_paral ;
    reg [3:0]   ai_nonblk, bi_nonblk ;
 
 //============================================================//
    //(1)Sequence block
    initial begin
        #5 ai_sequen         = 4'd5 ;    //at 5ns
        #5 bi_sequen         = 4'd8 ;    //at 10ns
    end
    //(2)fork block
    initial fork
        #5 ai_paral          = 4'd5 ;    //at 5ns
        #5 bi_paral          = 4'd8 ;    //at 5ns
    join
    //(3)non-block block
    initial fork
        #5 ai_nonblk         <= 4'd5 ;    //at 5ns
        #5 bi_nonblk         <= 4'd8 ;    //at 5ns
    join
 
endmodule

The simulation results are as follows :

As shown in the figure , Sequential block sequential execution , The first 10ns when , The signal bi_sequen Only assigned as 8.

Parallel block ,ai_paral And bi_paral The assignment of is performed simultaneously , So they are 5ns Is assigned .

Instead of blocking assignment , It can also achieve the same assignment effect as parallel blocks .