Content-addressable memory (CAM) is a special typeof computer memory used in certain very high speed searching applications.
1 //-----------------------------------------------------
2 // Design Name : cam
3 // File Name : cam.v
4 // Function : CAM
5 // Coder : Deepak Kumar Tala
6 //-----------------------------------------------------
7 module cam (
8 clk , // Cam clock
9 cam_enable , // Cam enable
10 cam_data_in , // Cam data to match
11 cam_hit_out , // Cam match has happened
12 cam_addr_out // Cam output address
13 );
14
15 parameter ADDR_WIDTH = 8;
16 parameter DEPTH = 1 << ADDR_WIDTH;
17 //------------Input Ports--------------
18 input clk;
19 input cam_enable;
20 input [DEPTH-1:0] cam_data_in;
21 //----------Output Ports--------------
22 output cam_hit_out;
23 output [ADDR_WIDTH-1:0] cam_addr_out;
24 //------------Internal Variables--------
25 reg [ADDR_WIDTH-1:0] cam_addr_out;
26 reg cam_hit_out;
27 reg [ADDR_WIDTH-1:0] cam_addr_combo;
28 reg cam_hit_combo;
29 reg found_match;
30 integer i;
31 //-------------Code Starts Here-------
32 always @(cam_data_in) begin
33 cam_addr_combo = {ADDR_WIDTH{1'b0}};
34 found_match = 1'b0;
35 cam_hit_combo = 1'b0;
36 for (i=0; ibegin
37 if (cam_data_in[i] && ! found_match) begin
38 found_match = 1'b1;
39 cam_hit_combo = 1'b1;
40 cam_addr_combo = i;
41 end else begin
42 found_match = found_match;
43 cam_hit_combo = cam_hit_combo;
44 cam_addr_combo = cam_addr_combo;
45 end
46 end
47 end
48
49 // Register the outputs
50 always @(posedge clk) begin
51 if (cam_enable) begin
52 cam_hit_out <= cam_hit_combo;
53 cam_addr_out <= cam_addr_combo;
54 end else begin
55 cam_hit_out <= 1'b0;
56 cam_addr_out <= {ADDR_WIDTH{1'b0}};
57 end
58 end
59
60 endmodule
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