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[/] [xulalx25soc/] [trunk/] [rtl/] [wbucompactlines.v] - Rev 40
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//////////////////////////////////////////////////////////////////////////////// // // Filename: wbucompactlines.v // // Project: XuLA2 board // // Purpose: Removes 'end of line' characters placed at the end of every // deworded word, unless we're idle or the line is too long. // This helps to format the output nicely to fit in an 80-character // display, should you need to do so for debugging. // // // Creator: Dan Gisselquist, Ph.D. // Gisselquist Technology, LLC // //////////////////////////////////////////////////////////////////////////////// // // Copyright (C) 2015, 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. // // License: GPL, v3, as defined and found on www.gnu.org, // http://www.gnu.org/licenses/gpl.html // // //////////////////////////////////////////////////////////////////////////////// // // // When to apply a new line? // When no prior new line exists // or when prior line length exceeds (72) // Between codewords (need inserted newline) // When bus has become idle (~wb_cyc)&&(~busys) // // So, if every codeword ends in a newline, what we // really need to do is to remove newlines. Thus, if // i_stb goes high while i_tx_busy, we skip the newline // unless the line is empty. ... But i_stb will always // go high while i_tx_busy. How about if the line // length exceeds 72, we do nothing, but record the // last word. If the last word was a <incomplete-thought> // // module wbucompactlines(i_clk, i_stb, i_nl_hexbits, o_stb, o_nl_hexbits, i_bus_busy, i_tx_busy, o_busy); input i_clk, i_stb; input [6:0] i_nl_hexbits; output reg o_stb; output reg [6:0] o_nl_hexbits; input i_bus_busy; input i_tx_busy; output wire o_busy; reg last_out_nl, last_in_nl; initial last_out_nl = 1'b1; initial last_in_nl = 1'b1; always @(posedge i_clk) if ((~i_tx_busy)&&(o_stb)) last_out_nl <= (o_nl_hexbits[6]); always @(posedge i_clk) if ((i_stb)&&(~o_busy)) last_in_nl <= (i_nl_hexbits[6]); // Now, let's count how long our lines are reg [6:0] linelen; initial linelen = 7'h00; always @(posedge i_clk) if ((~i_tx_busy)&&(o_stb)) begin if (o_nl_hexbits[6]) linelen <= 0; else linelen <= linelen + 7'h1; end reg full_line; initial full_line = 1'b0; always @(posedge i_clk) full_line <= (linelen > 7'd72); // Now that we know whether or not the last character was a newline, // and indeed how many characters we have in any given line, we can // selectively remove newlines from our output stream. initial o_stb = 1'b0; always @(posedge i_clk) if ((i_stb)&&(~o_busy)) begin o_stb <= (full_line)||(~i_nl_hexbits[6]); o_nl_hexbits <= i_nl_hexbits; end else if (~o_busy) begin o_stb <= (~i_tx_busy)&&(~i_bus_busy)&&(~last_out_nl)&&(last_in_nl); o_nl_hexbits <= 7'h40; end else if (~i_tx_busy) o_stb <= 1'b0; reg r_busy; initial r_busy = 1'b0; always @(posedge i_clk) r_busy <= (o_stb); assign o_busy = (r_busy)||(o_stb); /* output wire [27:0] o_dbg; assign o_dbg = { o_stb, o_nl_hexbits, o_busy, r_busy, full_line, i_bus_busy, linelen, i_tx_busy, i_stb, i_nl_hexbits }; */ endmodule
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