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////////////////////////////////////////////////////////////////////////////////
//
// Filename: wbusixchar.v
//
// Project: FPGA library
//
// Purpose: Supports a conversion from a six digit bus to a printable
// ASCII character representing those six bits. The encoding is
// as follows:
//
// 0-9 -> 0-9
// A-Z -> 10-35
// a-z -> 36-61
// @ -> 62
// % -> 63
//
// Note that decoding is stateless, yet requires one clock.
//
//
// Creator: Dan Gisselquist, Ph.D.
// Gisselquist Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2015-2017, Gisselquist Technology, LLC
//
// This program is free software (firmware): you can redistribute it and/or
// modify it under the terms of the GNU General Public License as published
// by the Free Software Foundation, either version 3 of the License, or (at
// your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. (It's in the $(ROOT)/doc directory. Run make with no
// target there if the PDF file isn't present.) If not, see
// <http://www.gnu.org/licenses/> for a copy.
//
// License: GPL, v3, as defined and found on www.gnu.org,
// http://www.gnu.org/licenses/gpl.html
//
//
////////////////////////////////////////////////////////////////////////////////
//
//
//
module wbusixchar(i_clk, i_stb, i_bits, o_stb, o_char, o_busy, i_busy);
input wire i_clk;
input wire i_stb;
input wire [6:0] i_bits;
output reg o_stb;
output reg [7:0] o_char;
output wire o_busy;
input wire i_busy;
initial o_char = 8'h00;
always @(posedge i_clk)
if ((i_stb)&&(~o_busy))
begin
if (i_bits[6])
o_char <= 8'h0a;
else if (i_bits[5:0] <= 6'h09) // A digit, WORKS
o_char <= "0" + { 4'h0, i_bits[3:0] };
else if (i_bits[5:0] <= 6'd35) // Upper case
o_char <= "A" + { 2'h0, i_bits[5:0] } - 8'd10; // -'A'+10
else if (i_bits[5:0] <= 6'd61)
o_char <= "a" + { 2'h0, i_bits[5:0] } - 8'd36;// -'a'+(10+26)
else if (i_bits[5:0] == 6'd62) // An '@' sign
o_char <= 8'h40;
else // if (i_char == 6'h63) // A '%' sign
o_char <= 8'h25;
end
always @(posedge i_clk)
if ((o_stb)&&(~i_busy))
o_stb <= 1'b0;
else if ((i_stb)&&(~o_stb))
o_stb <= 1'b1;
assign o_busy = o_stb;
endmodule