`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: Dept. of Computer Science, National Chiao Tung University
// Engineer: Chun-Jen Tsai
//
// Create Date: 2017/05/08 15:29:41
// Design Name:
// Module Name: lab6
// Project Name:
// Target Devices:
// Tool Versions:
// Description: The sample top module of lab 6: sd card reader. The behavior of
//              this module is as follows
//              1. When the SD card is initialized, display a message on the LCD.
//                 If the initialization fails, an error message will be shown.
//              2. The user can then press usr_btn[2] to trigger the sd card
//                 controller to read the super block of the sd card (located at
//                 block # 8192) into the SRAM memory.
//              3. During SD card reading time, the four LED lights will be turned on.
//                 They will be turned off when the reading is done.
//              4. The LCD will then displayer the sector just been read, and the
//                 first byte of the sector.
//              5. Everytime you press usr_btn[2], the next byte will be displayed.
//
// Dependencies: clk_divider, LCD_module, debounce, sd_card
//
// Revision:
// Revision 0.01 - File Created
// Additional Comments:
//
//////////////////////////////////////////////////////////////////////////////////

module lab6(
  // General system I/O ports
  input  clk,
  input  reset_n,
  input  [3:0] usr_btn,
  output [3:0] usr_led,

  // SD card specific I/O ports
  output spi_ss,
  output spi_sck,
  output spi_mosi,
  input  spi_miso,

  // 1602 LCD Module Interface
  output LCD_RS,
  output LCD_RW,
  output LCD_E,
  output [3:0] LCD_D
);

localparam [3:0] S_MAIN_INIT = 3'b000, S_MAIN_IDLE = 3'b001,
                 S_MAIN_WAIT = 3'b010, S_MAIN_READ = 3'b011,
                 S_MAIN_DONE = 3'b100, S_MAIN_CAL = 3'b101,
                 S_MAIN_SHOW = 3'b110;

// Declare system variables
wire btn_level, btn_pressed;
reg  prev_btn_level;
reg  [5:0] send_counter;
reg  [2:0] P, P_next;
reg  [9:0] sd_counter;
reg  [9:0] done_counter;
reg  [9:0] counter=0;
reg  [9:0] counter_2=0;
reg  [9:0] counter_the;
reg  [9:0] start_counter;
reg  [7:0] data_byte;
reg  [31:0] blk_addr;
reg  [31:0] start_blk_addr;
reg  [3:0] dlab_tag_match=0, dlab_end_match=0, dlab_the_match=0;
reg  [9:0] num_the=0;
reg  [9:0] num_the_p=0;
reg  start_flag, end_flag;
reg  not_this_block, not_this_block_2;
reg  [127:0] row_A = "SD card cannot  ";
reg  [127:0] row_B = "be initialized! ";
reg  [0:63] dlab_tag = "DLAB_TAG";
reg  [0:63] dlab_end = "DLAB_END";
reg  [0:23] THE = "THE";
reg  [0:23] the = "the";
reg  [0:56] print_out = "        ";
reg  done_flag; // Signals the completion of reading one SD sector.
reg  [0:7] word="@", word_1="@", word_2='h1 ,word_3 = "!",word_4='h2, word_5, word_6, word_7;
reg [0:31] p_addr, p_addr_1;
// Declare SD card interface signals
wire clk_sel;
wire clk_500k;
reg  rd_req;
reg  [31:0] rd_addr;
wire init_finished;
wire [7:0] sd_dout;
wire sd_valid;

// Declare the control/data signals of an SRAM memory block
wire [7:0] data_in;
wire [7:0] data_out;
wire [8:0] sram_addr;
wire       sram_we, sram_en;

assign clk_sel = (init_finished)? clk : clk_500k; // clock for the SD controller
assign usr_led = P;

clk_divider#(200) clk_divider0(
  .clk(clk),
  .reset(~reset_n),
  .clk_out(clk_500k)
);

debounce btn_db0(
  .clk(clk),
  .btn_input(usr_btn[2]),
  .btn_output(btn_level)
);

LCD_module lcd0(
  .clk(clk),
  .reset(~reset_n),
  .row_A(row_A),
  .row_B(row_B),
  .LCD_E(LCD_E),
  .LCD_RS(LCD_RS),
  .LCD_RW(LCD_RW),
  .LCD_D(LCD_D)
);

sd_card sd_card0(
  .cs(spi_ss),
  .sclk(spi_sck),
  .mosi(spi_mosi),
  .miso(spi_miso),

  .clk(clk_sel),
  .rst(~reset_n),
  .rd_req(rd_req),
  .block_addr(rd_addr),
  .init_finished(init_finished),
  .dout(sd_dout),
  .sd_valid(sd_valid)
);

sram ram0(
  .clk(clk),
  .we(sram_we),
  .en(sram_en),
  .addr(sram_addr),
  .data_i(data_in),
  .data_o(data_out)
);


//
// Enable one cycle of btn_pressed per each button hit
//
always @(posedge clk) begin
  if (~reset_n)
    prev_btn_level <= 0;
  else
    prev_btn_level <= btn_level;
end

assign btn_pressed = (btn_level == 1 && prev_btn_level == 0)? 1 : 0;

// ------------------------------------------------------------------------
// The following code sets the control signals of an SRAM memory block
// that is connected to the data output port of the SD controller.
// Once the read request is made to the SD controller, 512 bytes of data
// will be sequentially read into the SRAM memory block, one byte per
// clock cycle (as long as the sd_valid signal is high).
assign sram_we = sd_valid;          // Write data into SRAM when sd_valid is high.
assign sram_en = 1;                 // Always enable the SRAM block.
assign data_in = sd_dout;           // Input data always comes from the SD controller.
assign sram_addr = sd_counter[8:0]; // Set the driver of the SRAM address signal.
// End of the SRAM memory block
// ------------------------------------------------------------------------

// ------------------------------------------------------------------------
// FSM of the SD card reader that reads the super block (512 bytes)
always @(posedge clk) begin
  if (~reset_n) begin
    P <= S_MAIN_INIT;
    done_flag <= 0;
  end
  else begin
    P <= P_next;
    if (P == S_MAIN_DONE)
      done_flag <= 1;
    else if (P == S_MAIN_SHOW && P_next == S_MAIN_IDLE)
      done_flag <= 0;
    else
      done_flag <= done_flag;
  end
end



always @(*) begin // FSM next-state logic
  case (P)
    S_MAIN_INIT: // wait for SD card initialization
      if (init_finished == 1) P_next = S_MAIN_IDLE;
      else P_next = S_MAIN_INIT;
    S_MAIN_IDLE: // wait for button click
      if (btn_pressed == 1) P_next = S_MAIN_WAIT;
      else P_next = S_MAIN_IDLE;
    S_MAIN_WAIT: // issue a rd_req to the SD controller until it's ready
      P_next = S_MAIN_READ;
    S_MAIN_READ: // wait for the input data to enter the SRAM buffer
      if (sd_counter == 512)  P_next = S_MAIN_DONE;
      else P_next = S_MAIN_READ;
    S_MAIN_DONE: // read byte 0 of the superblock from sram[]
      P_next = S_MAIN_CAL;
    S_MAIN_CAL:
      if (dlab_end_match=='d7) P_next = S_MAIN_SHOW;
      else if (sd_counter =='d512) P_next = S_MAIN_WAIT;
      else P_next = S_MAIN_CAL;
    S_MAIN_SHOW:
      if (~reset_n) P_next = S_MAIN_INIT;
    else P_next = S_MAIN_SHOW;
    default:
      P_next = S_MAIN_IDLE;
  endcase
end

// FSM output logic: controls the 'rd_req' and 'rd_addr' signals.
always @(*) begin
  rd_req = (P == S_MAIN_WAIT);
  rd_addr = blk_addr;
end

always @(posedge clk) begin
  if (~reset_n) begin
    counter <= 0;
    counter_2 <= 0;
    counter_the <= 0;
    blk_addr <= 32'h2000;
    dlab_tag_match <=0;
    dlab_end_match <=0;
    dlab_the_match <=0;
    num_the <= 0;
    num_the_p <= 0;
    start_flag <= 0;
    end_flag <= 0;
  end
  if (P==S_MAIN_WAIT) begin
    not_this_block <= 0;
    not_this_block_2 <= 0;
  end

  if (P==S_MAIN_CAL) begin
    if(data_byte==dlab_tag[counter+:8]) begin
      dlab_tag_match <= dlab_tag_match + 1;
      counter <= counter + 8;
      not_this_block <= 0;
      if (dlab_tag_match == 'd7) begin
        start_flag <= 1;
      end
    end
    else begin
        dlab_tag_match <= 0;
        counter <= 0;
    end

	if(data_byte==dlab_end[counter_2+:8]) begin
      dlab_end_match <= dlab_end_match + 1;
      counter_2 <= counter_2 + 8;
      not_this_block_2 <= 0;

      if (dlab_end_match == 'd7) begin
        p_addr[0+:8]<=blk_addr[15:12];
        p_addr[8+:8]<=blk_addr[11:8];
        p_addr[16+:8]<=blk_addr[7:4];
        p_addr[24+:8]<=blk_addr[3:0];
        end_flag <= 1;
      end
    end
	else begin
        counter_2 <= 0;
        dlab_end_match <= 0;
    end



    if(((data_byte==the[counter_the+:8]) || (data_byte==THE[counter_the+:8])) ) begin
        dlab_the_match <= dlab_the_match + 1;
        counter_the <= counter_the + 8;
        if (dlab_the_match == 'd2) begin
          num_the <= num_the + 'd1;
          p_addr_1[0+:8]<=blk_addr[15:12];
          p_addr_1[8+:8]<=blk_addr[11:8];
          p_addr_1[16+:8]<=blk_addr[7:4];
          p_addr_1[24+:8]<=blk_addr[3:0];
        end
		if (dlab_the_match == 'd0) word <= data_byte;
        if (dlab_the_match == 'd1) word_1 <= data_byte;
        if (dlab_the_match == 'd2) word_2 <= data_byte;
    end
    else begin
        dlab_the_match <= 0;
        counter_the <= 0;
    end


  end

  if (P==S_MAIN_SHOW) num_the_p <= num_the;
  if (sd_counter == 'd512) blk_addr <= blk_addr+1;
end


always @(posedge clk) begin
  if (~reset_n || (P == S_MAIN_READ && P_next == S_MAIN_DONE) || ((P == S_MAIN_DONE) && (P_next == S_MAIN_WAIT)) || ((P == S_MAIN_CAL) && (P_next == S_MAIN_WAIT)) || ((P == S_MAIN_DONE) && (P_next == S_MAIN_CAL)))
    sd_counter <= 0;
  else if ((P == S_MAIN_READ && sd_valid) ||(P == S_MAIN_DONE && P_next==S_MAIN_CAL) || (P==S_MAIN_DONE && sd_counter<512) ||  (P==S_MAIN_CAL && sd_counter<512) ||((P == S_MAIN_CAL) && (P_next==S_MAIN_SHOW)))
    sd_counter <= sd_counter + 1;

end

//always @(posedge clk) begin
//  if(~reset_n || ((P == S_MAIN_DONE) && (P_next == S_MAIN_WAIT))) begin
//    done_counter <= 0;

//  end
//  else if ((P == S_MAIN_DONE) && (done_counter<512)) begin
//    done_counter <= done_counter +1;
//  end

//end

// FSM ouput logic: Retrieves the content of sram[] for display
always @(posedge clk) begin
  if (~reset_n) data_byte <= 8'b0;
  else if (sram_en && (P == S_MAIN_DONE || P==S_MAIN_CAL)) data_byte <= data_out;
  //else data_byte <= data_out;
end
// End of the FSM of the SD card reader
// ------------------------------------------------------------------------

// ------------------------------------------------------------------------
// LCD Display function.
always @(posedge clk) begin
  if (~reset_n) begin
    row_A = "SD card cannot  ";
    row_B = "be initialized! ";
  end else if (done_flag) begin
    row_A <= {word, word_1, word_2,  ((num_the_p[7:4] > 9)? "7" : "0") + num_the_p[7:4],   ((num_the_p[3:0] > 9)? "7" : "0") + num_the_p[3:0],word_5,word_6,word_7,((p_addr[0:7] > 9)? "7" : "0") + p_addr[0:7], ((p_addr[8:15] > 9)? "7" : "0") + p_addr[8:15],  ((p_addr[16:23] > 9)? "7" : "0") + p_addr[16:23],  ((p_addr[24:31] > 9)? "7" : "0") + p_addr[24:31]
                            , ((p_addr_1[0:7] > 9)? "7" : "0") + p_addr_1[0:7], ((p_addr_1[8:15] > 9)? "7" : "0") + p_addr_1[8:15],  ((p_addr_1[16:23] > 9)? "7" : "0") + p_addr_1[16:23],  ((p_addr_1[24:31] > 9)? "7" : "0") + p_addr_1[24:31]};
    //row_A <= {word, word_1};
    row_B <= { "Byte ",
               sd_counter[9:8] + "0",
               ((sd_counter[7:4] > 9)? "7" : "0") + sd_counter[7:4],
               ((sd_counter[3:0] > 9)? "7" : "0") + sd_counter[3:0],
               "h = ",
               ((data_byte[7:4] > 9)? "7" : "0") + data_byte[7:4],
               ((data_byte[3:0] > 9)? "7" : "0") + data_byte[3:0], "h." };
  end
  else if (P == S_MAIN_IDLE) begin
    row_A <= "Hit BTN2 to read";
    row_B <= "the SD card ... ";
  end
end
// End of the LCD display function
// ------------------------------------------------------------------------

endmodule