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Interfaces can contain Task and Functions. They can either reside inside the interfac block or can be external to interface, but inside the module which uses this interfaces. If the tasks or functions are defined in a module, using a hierarchical name, they must also be declared as extern in the interface or as export in a modport. |
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1 //+++++++++++++++++++++++++++++++++++++++++++++++++
2 // Define the interface
3 //+++++++++++++++++++++++++++++++++++++++++++++++++
4 interface task_function_if (input clk);
5 logic req;
6 logic gnt;
7 //=================================================
8 // Clocking block for tb modport
9 //=================================================
10 clocking cb @ (posedge clk);
11 input gnt;
12 output req;
13 endclocking
14 //=================================================
15 // Task inside a interface, You can basically
16 // Write a BFM, who's input can be a class or
17 // a mailbox, so on..... SO COOL!!!!
18 //=================================================
19 task drive_req (input integer delay, input bit value);
20 $display("@%0dns Before driving req %b from task at %m", $time, req);
21 repeat (delay) @ (posedge clk);
22 req = value;
23 $display("@%0dns Driving req %b from task at %m", $time, req);
24 endtask
25 //=================================================
26 // Mod port with exporting and importing tasks
27 //=================================================
28 modport dut (input clk,req, output gnt
29 //, export print_md, import print_tb
30 );
31 //=================================================
32 // Mod Port with exporting and importing tasks
33 //=================================================
34 modport tb (clocking cb, input clk,
35 import drive_req
36 //, print_md, export print_tb
37 );
38
39 endinterface
40 //+++++++++++++++++++++++++++++++++++++++++++++++++
41 // DUT Code
42 // Uses just the interface keyword
43 //+++++++++++++++++++++++++++++++++++++++++++++++++
44 module dut_ex (interface abc);
45 //=================================================
46 // Task print_md, which is exported
47 //=================================================
48 //task abc.print_md (input logic something);
49 // $display("@%0dns Inside %m : From print_md", $time);
50 // $display("Value of req %b gnt %b in %m",abc.req, abc.gnt);
51 //endtask
52 //=================================================
53 // Simple DUT Logic and calling task in another
54 // Module through interface
55 //=================================================
56 always @ (posedge abc.clk)
57 begin
58 abc.gnt <= abc.req;
59 $display("@%0dns Request is %b", $time, abc.req);
60 if (abc.req === 1'bx) begin
61 //abc.print_tb(1'bx);
62 end
63 if (abc.req === 1'b0) begin
64 //abc.print_tb(1'b0);
65 end
66 if (abc.req === 1'b1) begin
67 //abc.print_tb(1'b1);
68 end
69 end
70
71 endmodule
72
73 //+++++++++++++++++++++++++++++++++++++++++++++++++
74 // TB Code
75 // Uses just the interface keyword
76 //+++++++++++++++++++++++++++++++++++++++++++++++++
77 module tb_ex (interface xyz);
78 //=================================================
79 // Task print_tb, which is exported
80 //=================================================
81 //task xyz.print_tb (input bit something);
82 // $display("@%0dns %m Value of req : %b", $time, something);
83 //endtask
84 //=================================================
85 // Test vector generation with task in another
86 // Module and in interface calling
87 //=================================================
88 initial begin
89 xyz.cb.req <= 0;
90 xyz.drive_req(10,1);
91 xyz.drive_req(10,0);
92 //xyz.print_md(0);
93 #2 $finish;
94 end
95
96 endmodule
97 //+++++++++++++++++++++++++++++++++++++++++++++++++
98 // Top level testbench file
99 //+++++++++++++++++++++++++++++++++++++++++++++++++
100 module interface_task_function();
101 //=================================================
102 // Clock generator
103 //=================================================
104 logic clk = 0;
105 always #1 clk++;
106 //=================================================
107 // Interface instance
108 //=================================================
109 task_function_if tfif(clk);
110 //=================================================
111 // DUT and TB instance
112 //=================================================
113 dut_ex U_dut(tfif.dut);
114 tb_ex U_tb(tfif.tb);
115
116 endmodule
You could download file interface_task_function.sv here
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