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qaztronic |
//////////////////////////////////////////////////////////////////////
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//// ////
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//// Copyright (C) 2019 Authors and OPENCORES.ORG ////
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//// ////
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//// This source file may be used and distributed without ////
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//// restriction provided that this copyright statement is not ////
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//// removed from the file and that any derivative work contains ////
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//// the original copyright notice and the associated disclaimer. ////
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//// ////
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//// This source file is free software; you can redistribute it ////
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//// and/or modify it under the terms of the GNU Lesser General ////
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//// Public License as published by the Free Software Foundation; ////
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//// either version 2.1 of the License, or (at your option) any ////
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//// later version. ////
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//// ////
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//// This source is distributed in the hope that it will be ////
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//// useful, but WITHOUT ANY WARRANTY; without even the implied ////
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//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////
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//// PURPOSE. See the GNU Lesser General Public License for more ////
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//// details. ////
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//// ////
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//// You should have received a copy of the GNU Lesser General ////
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//// Public License along with this source; if not, download it ////
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//// from http://www.opencores.org/lgpl.shtml ////
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//// ////
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//////////////////////////////////////////////////////////////////////
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module
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barrel_shifter
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#(
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parameter W = 32,
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parameter D = W,
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parameter UB = $clog2(D)
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)
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(
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input direction, // right = 0, left = 1
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input op, // logical = 0, arithmetic = 1; left arithmetic not supported
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input [UB-1:0] amount, // 0 not allowed
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input [W-1:0] data_in,
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output [W-1:0] data_out,
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input reset,
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input clk
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);
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// --------------------------------------------------------------------
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wire [W-1:0] out [UB:0];
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wire shift_in = direction & op ? data_in[W-1] : 0;
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genvar j, k;
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// --------------------------------------------------------------------
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generate
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for(k = 0; k < D; k = k + 1)
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begin : reversal
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assign out[5][k] = direction ? data_in[k] : data_in[D - 1 - k];
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assign data_out[k] = direction ? out[0][k] : out[0][D - 1 - k];
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end
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endgenerate
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// --------------------------------------------------------------------
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generate
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for(j = 0; j < UB; j = j + 1)
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for(k = 0; k < D; k = k + 1)
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begin : shifter
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if(k > D - 1 - (2**j))
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assign out[j][k] = amount[j] ? shift_in : out[j+1][k];
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else
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assign out[j][k] = amount[j] ? out[j+1][k + (2**j)] : out[j+1][k];
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end
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endgenerate
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// --------------------------------------------------------------------
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endmodule
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