darksimv.v

/*
 * Copyright (c) 2018, Marcelo Samsoniuk
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 * 
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * 
 * * Neither the name of the copyright holder nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

`timescale 1ns / 1ps
`include "../rtl/config.vh"

// clock and reset logic

module darksimv;

    reg CLK = 0;
    
    reg RES = 1;

    initial while(1) #(500e6/`BOARD_CK) CLK = !CLK; // clock generator w/ freq defined by config.vh

    integer i;

    initial
    begin
`ifdef __ICARUS__
        $dumpfile("darksocv.vcd");
        $dumpvars();

    `ifdef __REGDUMP__
        for(i=0;i!=`RLEN;i=i+1)
        begin
            $dumpvars(0,soc0.core0.REGS[i]);
        end
    `endif
`endif
        $display("reset (startup)");
        #1e3    RES = 0;            // wait 1us in reset state
        //#1000e3 RES = 1;            // run  1ms
        //$display("reset (restart)");
        //#1e3    RES = 0;            // wait 1us in reset state
        //#1000e3 $finish();          // run  1ms
    end

    wire TX;
    wire RX = 1;

`ifdef __SDRAM__

    // sdram sim model!

    wire        S_NWE,S_CLK;
    wire  [1:0] S_DQM;
    reg  [15:0] S_DBFF = 0;  
    wire [15:0] S_DB = S_NWE ? S_DBFF : 16'hzzzz;

    always@(negedge S_CLK)
    begin
        if(S_NWE==0 && S_DQM[1]==0) S_DBFF[15:8] <= S_DB[15:8];
        if(S_NWE==0 && S_DQM[0]==0) S_DBFF[ 7:0] <= S_DB[ 7:0];
    end

`endif

    darksocv soc0
    (
        .XCLK(CLK),
        .XRES(|RES),
`ifdef __SDRAM__        
        .S_CLK(S_CLK),
        .S_NWE(S_NWE),
        .S_DQM(S_DQM),
        .S_DB (S_DB),
`endif        
        .UART_RXD(RX),
        .UART_TXD(TX)
    );

endmodule