92 lines
2.2 KiB
Verilog
92 lines
2.2 KiB
Verilog
// Copyright (c) 2000 Stephen Williams (steve@icarus.com)
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//
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// This source code is free software; you can redistribute it
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// and/or modify it in source code form under the terms of the GNU
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// General Public License as published by the Free Software
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// Foundation; either version 2 of the License, or (at your option)
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// any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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//
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/*
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* This module implements what essentially amounts to an array of DFF
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* devices with output enable. This test checks the operation of the
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* bufif0 and bufif1 devices.
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*/
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module grayGap (ad, clk, read, write);
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output [31:0] ad;
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input clk, read, write;
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reg [15:0] regff;
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bufif0 ad_drv [31:0] (ad, {16'b0, regff}, read);
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always @(posedge clk)
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if (write) regff = ad[15:0];
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endmodule
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module main;
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wire [31:0] ad;
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reg clk, read, write;
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reg [31:0] ad_val;
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reg ad_en;
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bufif1 ad_drv[31:0] (ad, ad_val, ad_en);
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grayGap test (ad, clk, read, write);
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always #10 clk = ~clk;
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initial begin
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clk = 1;
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read = 1;
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write = 0;
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$monitor($time, "ad=%b", ad);
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// Set up to write a value into the grayGap register.
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@(negedge clk)
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ad_val = 32'haaaa_aaaa;
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read = 1;
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write = 1;
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ad_en = 1;
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// The posedge has passed, now set up to read that value
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// out. Turn all the drivers off for a moment, to see that the
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// line becomes tri-state...
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@(negedge clk)
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ad_en = 0;
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write = 0;
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// Now read the value.
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#1 read = 0;
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#1 $display("Wrote %h, got %h", ad_val, ad);
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if (ad !== 32'b0000_0000_0000_0000_1010_1010_1010_1010) begin
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$display("FAILED -- ad is %b", ad);
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$finish;
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end
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#2 read = 1;
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$display("PASSED");
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$finish;
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end
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endmodule // main
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