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-rw-r--r--src/test/single_rosc.v122
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+//======================================================================
+//
+// single_rosc.v
+// -------------
+// Top level module for testing the digital ring oscillator. This
+// module basically instantiates an oscillator with registered inputs
+// and outputs to allow synthesis tools to do good placement and
+// timing of the oscillator parts.
+//
+// The module is used to test how the oscillator is mapped to
+// resources in different FPGAs, and what happens when the size
+// of the oscillator increases.
+// idea of using carry chain in adders as inverter by Bernd Paysan.
+//
+//
+//
+// Author: Joachim Strombergson
+// Copyright (c) 2015, NORDUnet A/S All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// - Redistributions of source code must retain the above copyright notice,
+// this list of conditions and the following disclaimer.
+//
+// - Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+//
+// - Neither the name of the NORDUnet nor the names of its contributors may
+// be used to endorse or promote products derived from this software
+// without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+//======================================================================
+
+module single_rosc
+ (
+ input wire clk,
+ input wire reset_n,
+
+ input wire we,
+
+ input wire [(WIDTH - 1) : 0] opa,
+ input wire [(WIDTH - 1) : 0] opb,
+
+ output wire dout
+ );
+
+ parameter WIDTH = 3;
+
+ //----------------------------------------------------------------
+ // Registers.
+ //----------------------------------------------------------------
+ reg [(WIDTH - 1) : 0] opa_reg;
+ reg [(WIDTH - 1) : 0] opb_reg;
+
+ reg we_reg;
+
+ reg dout_reg;
+
+ // Ugly in-line Xilinx attribute to preserve the registers.
+ (* equivalent_register_removal = "no" *)
+ wire dout_new;
+
+
+ //----------------------------------------------------------------
+ // Concurrent assignment.
+ //----------------------------------------------------------------
+ assign dout = dout_reg;
+
+
+ //----------------------------------------------------------------
+ // oscillator instance.
+ //----------------------------------------------------------------
+ rosc #(.WIDTH(WIDTH)) osc(
+ .clk(clk),
+ .we(we_reg),
+ .reset_n(reset_n),
+ .opa(opa_reg),
+ .opb(opb_reg),
+ .dout(dout_new)
+ );
+
+
+ //----------------------------------------------------------------
+ // reg_update
+ //----------------------------------------------------------------
+ always @ (posedge clk or negedge reset_n)
+ begin
+ if (!reset_n)
+ begin
+ opa_reg <= {WIDTH{1'b0}};
+ opb_reg <= {WIDTH{1'b0}};
+ we_reg <= 1'b0;
+ dout_reg <= 1'b0;
+ end
+ else
+ begin
+ we_reg <= we;
+ opa_reg <= opa;
+ opb_reg <= opb;
+ dout_reg <= dout_new;
+ end
+ end
+
+endmodule // single_rosc
+
+//======================================================================
+// EOF single_rosc.v
+//======================================================================