ship: Dscratch

== Ports ===========================================================
data  in:    inReadAddr
data out:    outReadData

data  in:    inWriteAddr
data  in:    inWriteData
token out:   outWriteDone

== Fleeterpreter ====================================================
    private long[] mem = new long[0];
    public long readMem(int addr) { return mem[addr]; }
    public void writeMem(int addr, long val) {
        if (addr >= mem.length) {
            long[] newmem = new long[addr * 2 + 1];
            System.arraycopy(mem, 0, newmem, 0, mem.length);
            mem = newmem;
        }
        mem[addr] = val;
    }

    public void service() {
        if (box_inReadAddr.dataReadyForShip() &&
            box_outReadData.readyForItemFromShip()) {
            box_outReadData.addDataFromShip((int)readMem(box_inReadAddr.removeDataForShip()));
        }

        if (box_inWriteAddr.dataReadyForShip() &&
            box_inWriteData.dataReadyForShip() &&
            box_outWriteDone.readyForItemFromShip()) {
            writeMem(box_inWriteAddr.removeDataForShip(),
                     box_inWriteData.removeDataForShip());
            box_outWriteDone.addTokenFromShip();
        }
    }

== FleetSim ==============================================================

== FPGA ==============================================================
`include "macros.v"
`define BRAM_ADDR_WIDTH 14
`define BRAM_DATA_WIDTH `DATAWIDTH
`define BRAM_NAME dscratch_bram
`include "bram.inc"

module dscratch (clk, 
               read_addr_r,    read_addr_a_,   read_addr_d,
               read_data_r_,   read_data_a,    read_data_d_,
               write_addr_r,   write_addr_a_,  write_addr_d,
               write_data_r,   write_data_a_,  write_data_d,
               write_done_r_,  write_done_a,   write_done_d_
              );

  input  clk;
  `input(read_addr_r,    read_addr_a,   read_addr_a_,   [(`DATAWIDTH-1):0],  read_addr_d)
  `output(read_data_r,   read_data_r_,  read_data_a,    [(`DATAWIDTH-1):0],  read_data_d_)
  `defreg(read_data_d_,                                 [(`DATAWIDTH-1):0],  read_data_d)

  `input(write_addr_r,   write_addr_a,  write_addr_a_,  [(`DATAWIDTH-1):0],  write_addr_d)
  `input(write_data_r,   write_data_a,  write_data_a_,  [(`DATAWIDTH-1):0],  write_data_d)
  `output(write_done_r,  write_done_r_, write_done_a,   [(`DATAWIDTH-1):0],  write_done_d_)
  `defreg(write_done_d_,                                [(`DATAWIDTH-1):0],  write_done_d)

  reg                           bram_we;
  wire                          bram_we_;
  assign bram_we_ = bram_we;
  wire [(`BRAM_DATA_WIDTH-1):0] bram_read_data;
  reg  [(`BRAM_ADDR_WIDTH-1):0] bram_write_address;
  wire [(`BRAM_ADDR_WIDTH-1):0] bram_read_address;
  reg  [(`BRAM_DATA_WIDTH-1):0] bram_write_data;
  wire [(`BRAM_DATA_WIDTH-1):0] bram_write_data_;
  assign bram_write_data_ = bram_write_data;
  `BRAM_NAME mybram(clk,
                    bram_we_,          bram_write_address,
                    bram_read_address, bram_write_data_,
                    not_connected,     bram_read_data);

  reg send_done;

  reg have_read;    initial have_read = 0;
  reg read_pending; initial read_pending = 0;
  assign bram_read_address = read_addr_d;

  always @(posedge clk) begin
    bram_we = 0;
    if (send_done) begin
      `onwrite(write_done_r, write_done_a)
        send_done = 0;
      end
    end else begin
      if (!write_addr_r && write_addr_a) write_addr_a = 0;
      if (!write_data_r && write_data_a) write_data_a = 0;
      if (write_addr_r && write_data_r) begin
        write_addr_a = 1;
        write_data_a = 1;
        bram_we = 1;
        send_done = 1;
        bram_write_address = write_addr_d;
        bram_write_data = write_data_d;
      end
    end

    if (read_pending) begin
        read_pending <= 0;
        have_read    <= 1;
        read_data_d  <= bram_read_data;
    end else if (have_read) begin
      `onwrite(read_data_r, read_data_a)
        have_read <= 0;
      end
    end else begin
      `onread(read_addr_r, read_addr_a)
        // ======= Careful with the timing here! =====================
        // We MUST capture bram_read_data on the very next clock since
        // read_addr_d is free to change after the next clock
        // ===========================================================
        read_pending <= 1;
      end
    end

  end

endmodule


== Constants ========================================================
== TeX ==============================================================

== Contributors =========================================================
Adam Megacz <megacz@cs.berkeley.edu>