// Copyright 2007 Altera Corporation. All rights reserved. // Altera products are protected under numerous U.S. and foreign patents, // maskwork rights, copyrights and other intellectual property laws. // // This reference design file, and your use thereof, is subject to and governed // by the terms and conditions of the applicable Altera Reference Design // License Agreement (either as signed by you or found at www.altera.com). By // using this reference design file, you indicate your acceptance of such terms // and conditions between you and Altera Corporation. In the event that you do // not agree with such terms and conditions, you may not use the reference // design file and please promptly destroy any copies you have made. // // This reference design file is being provided on an "as-is" basis and as an // accommodation and therefore all warranties, representations or guarantees of // any kind (whether express, implied or statutory) including, without // limitation, warranties of merchantability, non-infringement, or fitness for // a particular purpose, are specifically disclaimed. By making this reference // design file available, Altera expressly does not recommend, suggest or // require that this reference design file be used in combination with any // other product not provided by Altera. ///////////////////////////////////////////////////////////////////////////// module mask_16 (in,mask); input [3:0] in; output [15:0] mask; reg [15:0] mask; parameter FROM_MSB = 1'b1; parameter DIAG_ONES = 1'b1; generate if (!FROM_MSB && !DIAG_ONES) begin always @(in) begin case (in) 4'd0: mask=16'b0000000000000000; 4'd1: mask=16'b0000000000000001; 4'd2: mask=16'b0000000000000011; 4'd3: mask=16'b0000000000000111; 4'd4: mask=16'b0000000000001111; 4'd5: mask=16'b0000000000011111; 4'd6: mask=16'b0000000000111111; 4'd7: mask=16'b0000000001111111; 4'd8: mask=16'b0000000011111111; 4'd9: mask=16'b0000000111111111; 4'd10: mask=16'b0000001111111111; 4'd11: mask=16'b0000011111111111; 4'd12: mask=16'b0000111111111111; 4'd13: mask=16'b0001111111111111; 4'd14: mask=16'b0011111111111111; 4'd15: mask=16'b0111111111111111; default: mask=0; endcase end end else if ( FROM_MSB && !DIAG_ONES) begin always @(in) begin case (in) 4'd0: mask=16'b0000000000000000; 4'd1: mask=16'b1000000000000000; 4'd2: mask=16'b1100000000000000; 4'd3: mask=16'b1110000000000000; 4'd4: mask=16'b1111000000000000; 4'd5: mask=16'b1111100000000000; 4'd6: mask=16'b1111110000000000; 4'd7: mask=16'b1111111000000000; 4'd8: mask=16'b1111111100000000; 4'd9: mask=16'b1111111110000000; 4'd10: mask=16'b1111111111000000; 4'd11: mask=16'b1111111111100000; 4'd12: mask=16'b1111111111110000; 4'd13: mask=16'b1111111111111000; 4'd14: mask=16'b1111111111111100; 4'd15: mask=16'b1111111111111110; default: mask=0; endcase end end else if (!FROM_MSB && DIAG_ONES) begin always @(in) begin case (in) 4'd0: mask=16'b0000000000000001; 4'd1: mask=16'b0000000000000011; 4'd2: mask=16'b0000000000000111; 4'd3: mask=16'b0000000000001111; 4'd4: mask=16'b0000000000011111; 4'd5: mask=16'b0000000000111111; 4'd6: mask=16'b0000000001111111; 4'd7: mask=16'b0000000011111111; 4'd8: mask=16'b0000000111111111; 4'd9: mask=16'b0000001111111111; 4'd10: mask=16'b0000011111111111; 4'd11: mask=16'b0000111111111111; 4'd12: mask=16'b0001111111111111; 4'd13: mask=16'b0011111111111111; 4'd14: mask=16'b0111111111111111; 4'd15: mask=16'b1111111111111111; default: mask=0; endcase end end else if ( FROM_MSB && DIAG_ONES) begin always @(in) begin case (in) 4'd0: mask=16'b1000000000000000; 4'd1: mask=16'b1100000000000000; 4'd2: mask=16'b1110000000000000; 4'd3: mask=16'b1111000000000000; 4'd4: mask=16'b1111100000000000; 4'd5: mask=16'b1111110000000000; 4'd6: mask=16'b1111111000000000; 4'd7: mask=16'b1111111100000000; 4'd8: mask=16'b1111111110000000; 4'd9: mask=16'b1111111111000000; 4'd10: mask=16'b1111111111100000; 4'd11: mask=16'b1111111111110000; 4'd12: mask=16'b1111111111111000; 4'd13: mask=16'b1111111111111100; 4'd14: mask=16'b1111111111111110; 4'd15: mask=16'b1111111111111111; default: mask=0; endcase end end endgenerate endmodule