96 lines
2.6 KiB
Verilog
96 lines
2.6 KiB
Verilog
/*
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* Copyright (c) 2000 Guy Hutchison (ghutchis@pacbell.net)
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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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module pullupdown;
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// declare several bussed wires
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wire pull_up_1, pull_down_1;
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wire [7:0] pull_up_8, pull_down_8;
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reg error;
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// assign pullups to each wire
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pullup (pull_up_1);
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pulldown (pull_down_1);
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pullup u8 [7:0] (pull_up_8);
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pulldown d8 [7:0] (pull_down_8);
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// create tristate drivers for each wire
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reg driver_1;
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reg [7:0] driver_8;
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assign pull_up_1 = driver_1;
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assign pull_down_1 = driver_1;
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assign pull_up_8 = driver_8;
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assign pull_down_8 = driver_8;
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initial
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begin : test_block
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integer i;
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// turn off all drivers
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driver_1 = 1'bz;
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driver_8 = 8'bz;
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error = 0;
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#1;
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// check default values
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if ((pull_up_1 !== 1'b1) || (pull_down_1 !== 1'b0) ||
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(pull_up_8 !== 8'hFF) || (pull_down_8 !== 8'h00)) begin
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$display("driver_8=%b, pull_up_8=%b, pull_down_8=%b",
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driver_8, pull_up_8, pull_down_8);
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$display("driver_1=%b, pull_up_1=%b, pull_down_1=%b",
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driver_1, pull_up_1, pull_down_1);
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error = 1;
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end
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for (i=0; i<256; i=i+1)
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begin
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driver_1 = ~driver_1;
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driver_8 = i;
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$display ("Testing drivers with value %h", driver_8);
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#1;
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check_drivers;
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#10;
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end
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if (error)
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$display ("FAILED - pullupdown ");
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else $display ("PASSED");
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end // block: test_block
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task check_drivers;
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begin
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if ((pull_up_1 !== driver_1) || (pull_down_1 !== driver_1) ||
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(pull_up_8 !== driver_8) || (pull_down_8 !== driver_8)) begin
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$display("driver_8=%b, pull_up_8=%b, pull_down_8=%b",
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driver_8, pull_up_8, pull_down_8);
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$display("driver_1=%b, pull_up_1=%b, pull_down_1=%b",
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driver_1, pull_up_1, pull_down_1);
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error = 1;
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end
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end
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endtask // check_drivers
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endmodule // pullupdown
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