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////////////////////////////////////////////////////////////////////////////////

//

// Filename:    wboled.v

//

// Project:     OpenArty, an entirely open SoC based upon the Arty platform

//

// Purpose:     

//

// Creator:     Dan Gisselquist, Ph.D.

//              Gisselquist Technology, LLC

//

////////////////////////////////////////////////////////////////////////////////

//

// Copyright (C) 2015-2016, 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  wboled(i_clk, i_cyc, i_stb, i_we, i_addr, i_data,

                        o_ack, o_stall, o_data,

                o_sck, o_cs_n, o_mosi, o_dbit,

                o_pwr, o_int);

        parameter       CBITS=4; // 2^4*2@5ns -> 160ns/clock > 150ns min

        input                   i_clk, i_cyc, i_stb, i_we;

        input           [1:0]    i_addr;

        input           [31:0]   i_data;

        output  reg             o_ack;

        output  wire            o_stall;

        output  reg     [31:0]   o_data;

        output  wire            o_sck, o_cs_n, o_mosi, o_dbit;

        output  reg     [2:0]    o_pwr;

        output  wire            o_int;

        reg             dev_wr, dev_dbit;

        reg     [31:0]   dev_word;

        reg     [1:0]    dev_len;

        wire            dev_busy;

        lloled  #(CBITS)

                lwlvl(i_clk, dev_wr, dev_dbit, dev_word, dev_len, dev_busy,

                        o_sck, o_cs_n, o_mosi, o_dbit);

        reg             r_busy;

        reg     [3:0]    r_len;

        reg     [31:0]   r_a, r_b;

        always @(posedge i_clk)

                if ((i_stb)&&(i_we))

                begin

                        if (i_addr[1:0]==2'b01)

                                r_a <= i_data;

                        if (i_addr[1:0]==2'b10)

                                r_b <= i_data;

                end else if (r_cstb)

                begin

                        r_a <= 32'h00;

                        r_b <= 32'h00;

                end

        always @(posedge i_clk)

        begin

                case (i_addr)

                2'b00: o_data <= { 13'h00, o_pwr, 8'h00, r_len, 3'h0, r_busy };

                2'b01: o_data <= r_a;

                2'b10: o_data <= r_b;

                2'b11: o_data <= { 13'h00, o_pwr, 8'h00, r_len, 3'h0, r_busy };

                endcase

        end

        initial o_ack = 1'b0;

        always @(posedge i_clk)

                o_ack <= i_stb;

        assign  o_stall = 1'b0;

        reg     r_cstb, r_dstb, r_pstb;

        reg     [23:0]   r_data;

        initial r_cstb = 1'b0;

        initial r_dstb = 1'b0;

        initial r_pstb = 1'b0;

        always @(posedge i_clk)

                r_cstb <= (i_stb)&&(i_addr[1:0]==2'b00);

        always @(posedge i_clk)

                r_dstb <= (i_stb)&&(i_addr[1:0]==2'b11)&&(i_data[22:20]==3'h0);

        always @(posedge i_clk)

                r_pstb <= (i_stb)&&(i_addr[1:0]==2'b11)&&(i_data[22:20]!=3'h0);

        always @(posedge i_clk)

                r_data <= i_data[23:0];

        initial o_pwr = 3'h0;

        always @(posedge i_clk)

                if (r_pstb)

                        o_pwr <= ((o_pwr)&(~r_data[22:20]))

                                        |((i_data[18:16])&(r_data[22:20]));

        reg     [3:0]    b_len;

        always @(posedge i_clk)

                casez(i_data[31:28])

                4'b000?: b_len <= (i_data[16])? 4'h1:4'h2;

                4'b0010: b_len <= 4'h3;

                4'b0011: b_len <= 4'h4;

                4'b0100: b_len <= 4'h5;

                4'b0101: b_len <= 4'h6;

                4'b0110: b_len <= 4'h7;

                4'b0111: b_len <= 4'h8;

                4'b1000: b_len <= 4'h9;

                4'b1001: b_len <= 4'ha;

                4'b1010: b_len <= 4'hb;

                default: b_len <= 4'h0;

                endcase

        reg     [87:0]   r_sreg;

        initial r_busy = 1'b0;

        always @(posedge i_clk)

        if ((~r_busy)&&(r_cstb))

        begin

                dev_wr   <= 1'b0;

                dev_dbit <= 1'b0;

                r_sreg <= { r_data[23:0], r_a, r_b };

                r_len <= b_len;

                r_busy <= (b_len != 4'h0);

                if (b_len == 4'h1)

                        r_sreg[87:72] <= { r_data[7:0], r_data[7:0] };

                else if (b_len == 4'h2)

                        r_sreg[87:72] <= r_data[15:0];

                else

                        r_sreg[87:72] <= r_data[23:8];

        end else if ((~dev_busy)&&(r_dstb))

        begin

                dev_wr   <= 1'b0;

                dev_dbit <= 1'b1;

                r_sreg <= { r_data[15:0], 72'h00 };

                r_len <= 4'h2;

                r_busy <= 1'b1;

        end else if ((r_busy)&&(~dev_busy))

        begin

                dev_word <= r_sreg[87:56];

                r_sreg <= { r_sreg[55:0], 32'h00 };

                dev_len <= (r_len > 4'h4)? 2'b11:(r_len[1:0]+2'b11);

                r_len <= (r_len > 4'h4) ? (r_len-4'h4):0;

        end else if (r_busy)

                r_busy <= (r_len != 4'h0);

        assign  o_int = (~r_busy);

endmodule