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Device Under Test
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1 //-----------------------------------------------------
2 // Design Name : syn_fifo
3 // File Name : syn_fifo.v
4 // Function : Synchronous (single clock) FIFO
5 // Coder : Deepak Kumar Tala
6 //-----------------------------------------------------
7 module syn_fifo (
8 clk , // Clock input
9 rst , // Active high reset
10 wr_cs , // Write chip select
11 rd_cs , // Read chipe select
12 data_in , // Data input
13 rd_en , // Read enable
14 wr_en , // Write Enable
15 data_out , // Data Output
16 empty , // FIFO empty
17 full // FIFO full
18 );
19
20 // FIFO constants
21 parameter DATA_WIDTH = 8;
22 parameter ADDR_WIDTH = 8;
23 parameter RAM_DEPTH = (1 << ADDR_WIDTH);
24 // Port Declarations
25 input clk ;
26 input rst ;
27 input wr_cs ;
28 input rd_cs ;
29 input rd_en ;
30 input wr_en ;
31 input [DATA_WIDTH-1:0] data_in ;
32 output full ;
33 output empty ;
34 output [DATA_WIDTH-1:0] data_out ;
35
36 //-----------Internal variables-------------------
37 reg [ADDR_WIDTH-1:0] wr_pointer;
38 reg [ADDR_WIDTH-1:0] rd_pointer;
39 reg [ADDR_WIDTH :0] status_cnt;
40 reg [DATA_WIDTH-1:0] data_out ;
41 wire [DATA_WIDTH-1:0] data_ram ;
42
43 //-----------Variable assignments---------------
44 assign full = (status_cnt == (RAM_DEPTH-1));
45 assign empty = (status_cnt == 0);
46
47 //-----------Code Start---------------------------
48 always @ (posedge clk or posedge rst)
49 begin : WRITE_POINTER
50 if (rst) begin
51 wr_pointer <= 0;
52 end else if (wr_cs && wr_en ) begin
53 wr_pointer <= wr_pointer + 1;
54 end
55 end
56
57 always @ (posedge clk or posedge rst)
58 begin : READ_POINTER
59 if (rst) begin
60 rd_pointer <= 0;
61 end else if (rd_cs && rd_en ) begin
62 rd_pointer <= rd_pointer + 1;
63 end
64 end
65
66 always @ (posedge clk or posedge rst)
67 begin : READ_DATA
68 if (rst) begin
69 data_out <= 0;
70 end else if (rd_cs && rd_en ) begin
71 data_out <= data_ram;
72 end
73 end
74
75 always @ (posedge clk or posedge rst)
76 begin : STATUS_COUNTER
77 if (rst) begin
78 status_cnt <= 0;
79 // Read but no write.
80 end else if ((rd_cs && rd_en) && ! (wr_cs && wr_en)
81 && (status_cnt ! = 0)) begin
82 status_cnt <= status_cnt - 1;
83 // Write but no read.
84 end else if ((wr_cs && wr_en) && ! (rd_cs && rd_en)
85 && (status_cnt ! = RAM_DEPTH)) begin
86 status_cnt <= status_cnt + 1;
87 end
88 end
89
90 ram_dp_ar_aw #(DATA_WIDTH,ADDR_WIDTH)DP_RAM (
91 .address_0 (wr_pointer) , // address_0 input
92 .data_0 (data_in) , // data_0 bi-directional
93 .cs_0 (wr_cs) , // chip select
94 .we_0 (wr_en) , // write enable
95 .oe_0 (1'b0) , // output enable
96 .address_1 (rd_pointer) , // address_q input
97 .data_1 (data_ram) , // data_1 bi-directional
98 .cs_1 (rd_cs) , // chip select
99 .we_1 (1'b0) , // Read enable
100 .oe_1 (rd_en) // output enable
101 );
102
103 endmodule
You could download file syn_fifo.v here
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1 //-----------------------------------------------------
2 // Design Name : ram_dp_ar_aw
3 // File Name : ram_dp_ar_aw.v
4 // Function : Asynchronous read write RAM
5 // Coder : Deepak Kumar Tala
6 //-----------------------------------------------------
7 module ram_dp_ar_aw (
8 address_0 , // address_0 Input
9 data_0 , // data_0 bi-directional
10 cs_0 , // Chip Select
11 we_0 , // Write Enable/Read Enable
12 oe_0 , // Output Enable
13 address_1 , // address_1 Input
14 data_1 , // data_1 bi-directional
15 cs_1 , // Chip Select
16 we_1 , // Write Enable/Read Enable
17 oe_1 // Output Enable
18 );
19
20 parameter DATA_WIDTH = 8 ;
21 parameter ADDR_WIDTH = 8 ;
22 parameter RAM_DEPTH = 1 << ADDR_WIDTH;
23
24 //--------------Input Ports-----------------------
25 input [ADDR_WIDTH-1:0] address_0 ;
26 input cs_0 ;
27 input we_0 ;
28 input oe_0 ;
29 input [ADDR_WIDTH-1:0] address_1 ;
30 input cs_1 ;
31 input we_1 ;
32 input oe_1 ;
33
34 //--------------Inout Ports-----------------------
35 inout [DATA_WIDTH-1:0] data_0 ;
36 inout [DATA_WIDTH-1:0] data_1 ;
37
38 //--------------Internal variables----------------
39 reg [DATA_WIDTH-1:0] data_0_out ;
40 reg [DATA_WIDTH-1:0] data_1_out ;
41 reg [DATA_WIDTH-1:0] mem [0:RAM_DEPTH-1];
42
43 //--------------Code Starts Here------------------
44 // Memory Write Block
45 // Write Operation : When we_0 = 1, cs_0 = 1
46 always @ (address_0 or cs_0 or we_0 or data_0
47 or address_1 or cs_1 or we_1 or data_1)
48 begin : MEM_WRITE
49 if ( cs_0 && we_0 ) begin
50 mem[address_0] <= data_0;
51 end else if (cs_1 && we_1) begin
52 mem[address_1] <= data_1;
53 end
54 end
55
56 // Tri-State Buffer control
57 // output : When we_0 = 0, oe_0 = 1, cs_0 = 1
58 assign data_0 = (cs_0 && oe_0 && ! we_0) ? data_0_out : 8'bz;
59
60 // Memory Read Block
61 // Read Operation : When we_0 = 0, oe_0 = 1, cs_0 = 1
62 always @ (address_0 or cs_0 or we_1 or oe_0)
63 begin : MEM_READ_0
64 if (cs_0 && ! we_0 && oe_0) begin
65 data_0_out <= mem[address_0];
66 end else begin
67 data_0_out <= 0;
68 end
69 end
70
71 //Second Port of RAM
72 // Tri-State Buffer control
73 // output : When we_0 = 0, oe_0 = 1, cs_0 = 1
74 assign data_1 = (cs_1 && oe_1 && ! we_1) ? data_1_out : 8'bz;
75 // Memory Read Block 1
76 // Read Operation : When we_1 = 0, oe_1 = 1, cs_1 = 1
77 always @ (address_1 or cs_1 or we_1 or oe_1)
78 begin : MEM_READ_1
79 if (cs_1 && ! we_1 && oe_1) begin
80 data_1_out <= mem[address_1];
81 end else begin
82 data_1_out <= 0;
83 end
84 end
85
86 endmodule // End of Module ram_dp_ar_aw
You could download file ram_dp_ar_aw.v here
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HDL Testbench Top
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1 `include "ram_dp_ar_aw.v"
2 `include "syn_fifo.v"
3
4 module top();
5
6 parameter DATA_WIDTH = 8;
7 parameter ADDR_WIDTH = 3;
8
9 reg clk, rst, wr_cs, rd_cs;
10 reg rd_en, wr_en;
11 reg [DATA_WIDTH-1:0] data_in ;
12 wire full, empty;
13 wire [DATA_WIDTH-1:0] data_out ;
14
15 initial begin
16 clk = 0;
17 rst = 0;
18 wr_cs = 0;
19 rd_cs = 0;
20 rd_en = 0;
21 wr_en = 0;
22 data_in = 0;
23 end
24
25 always #1 clk = ~clk;
26
27 syn_fifo #(DATA_WIDTH,ADDR_WIDTH) fifo(
28 .clk (clk), // Clock input
29 .rst (rst), // Active high reset
30 .wr_cs (wr_cs), // Write chip select
31 .rd_cs (rd_cs), // Read chipe select
32 .data_in (data_in), // Data input
33 .rd_en (rd_en), // Read enable
34 .wr_en (wr_en), // Write Enable
35 .data_out (data_out),// Data Output
36 .empty (empty), // FIFO empty
37 .full (full) // FIFO full
38 );
39
40 endmodule
You could download file specman_examples here
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E Testbench Top
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1 <'
2 import fifo_clk.e;
3 import fifo_sb.e;
4 import fifo_driver.e;
5
6 struct fifo_tb {
7 scoreboard : fifo_sb;
8
9 driver : fifo_driver;
10 keep driver.sb == scoreboard;
11
12 go()@sys.clk is {
13 start driver.go();
14 };
15 };
16
17 extend sys {
18 tb : fifo_tb;
19 run() is also {
20 start tb.go();
21 };
22 };
23 '>
You could download file specman_examples here
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FIFO Clock
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1 <'
2 extend sys {
3 event clk is rise('top.clk') @sim;
4 };
5 '>
You could download file specman_examples here
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