Ch5 Basic OOP.ppt

1、Ch5,Basic OOP,OOB Terminology,Class a basic building block containing routines and variables. The analogue in Verilog is a module. Object an instance of a class. In Verilog, you need to instantiate a module to use it. Handle a pointer to an object. In Verilog, you use the name of an instance when yo

2、u refer to signals and methods from outside the module. An OOP handle is like the address of the object, but is stored in a pointer that can only refer to one type. Property a variable that holds data. In Verilog, this is a signal such as a register or wire. Method the procedural code that manipulat

3、es variables, contained in tasks and functions. Verilog modules have tasks and functions plus initial and always blocks. Prototype the header of a routine that shows the name, type, and argument list. The body of the routine contains the executable code.,Defining A Simple Class,class Transaction; lo

4、gic 31:0 addr; logic kind; logic 63:0 data; function new(logic 31:0 addr); this.addr = addr; this.kind = x; this.data = x; endfunction function void display(); $display(“addr=%h, kind=%b, data=%h”, addr, kind, data); endfunction endclass,You can define a class in a program, module, package, or outsi

5、de of any of these.,Defining Methods Outside,class Transaction; logic 31:0 addr; logic kind; logic 63:0 data; extern function new(); extern function void display(); endclass,function Transaction:new(logic 31:0 addr); this.addr = addr; this.kind = x; this.data = x; endfunction: new function void Tran

6、saction:display(); $display(“addr=%h, kind=%b, data=%h”, addr, kind, data); endfunction: display,Method prototype must match the one in the body.,Using One Class Inside Another,/normal order class Statistics; . endclass class Transaction; Statistics stats; . endclass,/use a undefined class typedef c

7、lass Statistics; class Transaction; Statistics stats; . endclass class Statistics; . endclass,Using A Simple Class,Transaction tr_gen; Transaction tr_drv; initial begin tr_gen = new(32b7788); tr_drv = new(32b8877); tr_gen.kind = 1b1; tr_drv.data = b0; tr_gen.display(); tr_drv.display(); end,Classes

8、can be used in programs and modules.,Handle and ObjectConstructor and Deallocation,Transaction tr_gen, tr_drv; tr_gen = new; tr_drv = tr_gen; tr_gen = new; tr_gen = null;,Stack,tr_gen,tr_drv,Static Varibles,class Transaction; static int count = 0; int id; function new(); id = count+; / Set ID, bump

9、count endfunction endclass Transaction t1, t2; initial begin t1 = new(); / 1st instance, id=0, count=1 t2 = new(); / 2nd instance, id=1, count=2 $display(Second id=%d, count=%d, t2.id, t2.count); end,Stack,heap,count,Passing Objects to Methods,class Transaction; logic 31:0 addr; function new(logic 3

10、1:0 addr); this.addr = addr; endfunction function void display(); $display(addr); endfunction endclass,program testgen; task transmit(Transaction t); t.addr = t.addr 2; endtask Transaction t; initial begin t = new(32h0033); $display(before transmit); t.display(); transmit(t); $display(after transmit

11、); t.display(); end endprogram,There is a mistake in book “SystemVerilog for Verification, 2nd Edition” on page 147.,Modifying a Handle in a Task,class Transaction; logic 31:0 addr; function new(logic 31:0 addr); this.addr = addr; endfunction function void display(); $display(addr); endfunction endc

12、lass,program testgen; task transmit(Transaction t); t = new(32h3300); t.addr = t.addr 2; endtask Transaction t; initial begin t = new(32h0033); $display(before transmit); t.display(); transmit(t); $display(after transmit); t.display(); end endprogram,Modifying a Handle in a Task,class Transaction; l

13、ogic 31:0 addr; function new(logic 31:0 addr); this.addr = addr; endfunction function void display(); $display(addr); endfunction endclass,program testgen; task transmit(ref Transaction t); t = new(32h3300); t.addr = t.addr 2; endtask Transaction t; initial begin t = new(32h0033); $display(before tr

14、ansmit); t.display(); transmit(t); $display(after transmit); t.display(); end endprogram,Modifying Objects in Flight,/ buggy generator task generator_bad(int n); Transaction t; t = new(); repeat (n) begin t.addr = $random(); transmit(t); end endtask,/ good generator task generator_bad(int n); Transa

15、ction t; repeat (n) begin t = new(); t.addr = $random(); transmit(t); end endtask,Arrays of Handles,class Transaction; logic 31:0 addr; function new(logic 31:0 addr = x); this.addr = addr; endfunction function void display(); $display(addr = %h, addr); endfunction endclass,program testgen; Transacti

16、on t; initial begin t = new5; foreach(ti) begin ti = new(i); ti.display(); end end endprogram,Copying Objects,class Transaction; logic 31:0 addr; function new(logic 31:0 addr); this.addr = addr; endfunction function void display(); $display(addr); endfunction endclass,program testgen; Transaction t1

17、, t2; initial begin t1 = new(32h0033); t2 = new(32h0044); t2 = t1; t1.display(); t2.display(); end endprogram,What happened?,Copying Objects,The 1st situation.,Stack,t1,t2,t2 = t1;,Copying Objects,The 2st situation.,Stack,t1,t2,Copying a simple class with new, t2 = new t1;,Copying Objects,The 3st si

18、tuation,Stack,t1,t2,using ref before arguments in task/function,Copying Objects,Copying a complex class with new,class Statistics; int id; function new(); id = 0; endfunction endclass class Transaction; logic 31:0 addr; Statistics stat; function new(logic 31:0 addr); this.addr = addr; this.stat = ne

19、w; endfunction endclass,program testgen; Transaction t1, t2; initial begin t1 = new(32h0003); t2 = new(32h0004); t2 = new t1; t2.stat.id = -1; $display(t1.stat.id); $display(t2.stat.addr); end endprogram,Copying Objects,Copying a complex class with new,Stack,t1,t2,stat,stat,addr,addr,Write Your Own Simple Copy,class Transaction; logic 31:0 addr; function new(logic 31:0 addr = x); this.addr = addr; endfunction function Transaction copy(); Transaction dst = new; dst.addr = this.addr; return d