//////////////////////////////////////////////////////////////////////////////////
// Company                  :   NPK TAIR
// Engineer                 :   Yuri Donskoy
// 
// Create Date (dd/mm/yyyy) :   16.05.2019
// Design Name              :
// Module Name              :
// Project Name             :
// Target Devices           :
// Tool versions            :
// Description              :
//
// Dependencies             : 
// 
// Revision                 :   0.01 - File Created
// Additional Comments      :
//        
//////////////////////////////////////////////////////////////////////////////////

module PeriphSpiInit (
    clk_i,
    rst_i,

    enable_i,

    mosi_o,
    sck_o,
    ss_o,

    done_o
);

//================================================================================
//
//  FUNCTIONS
//
//================================================================================

    function integer bit_num;
        input integer value;
        begin
            bit_num = 0;
            while (value > 0) begin
                value   = value >> 1;
                bit_num = bit_num + 1;
            end
        end
    endfunction

//================================================================================
//
//  PARAMETER/LOCALPARAM
//
//================================================================================

    parameter   DATA_WIDTH              = 24;
    parameter   DATA_NUM                = 26; 
    parameter   ROM_INIT_FILE           = "./initFiles/AdcInitData.txt";
    parameter   FILE_DATA_BASE          = "HEX";
    parameter   SPI_CLK_DIVISOR_POWER   = 4;
    parameter   SPI_CPOL                = 0;
    parameter   SPI_CPHA                = 0;
    parameter   SPI_DATA_DIRECTION      = "MSB";   //  MSB or LSB
    parameter   SPI_EN_START_DELAY      = "NO";     //  YES or NO

    localparam  ROM_ADDR_WIDTH          = bit_num(DATA_NUM);

//================================================================================
//
//  STATE MACHINE STATES
//
//================================================================================

    localparam  [7:0]   SM_RST_S        = 8'd0;
    localparam  [7:0]   SM_SEND_DATA_S  = 8'd2;
    localparam  [7:0]   SM_READ_DATA_S  = 8'd3;
    localparam  [7:0]   SM_WAIT_SPI_S   = 8'd4;
    localparam  [7:0]   SM_DONE_S       = 8'd5;

//================================================================================
//
//  PORTS
//
//================================================================================

    input       clk_i;
    input       rst_i;
    input       enable_i;
    output      mosi_o;
    output      sck_o;
    output      ss_o;
    output      done_o;

//================================================================================
//
//  REG/WIRE
//
//================================================================================

    reg     [ROM_ADDR_WIDTH-1:0]    rom_addr;
    reg                             rom_valid;
    wire    [DATA_WIDTH-1:0]        rom_data;
    reg     [ROM_ADDR_WIDTH-1:0]    rom_addr_next;
    wire                            spi_ready;
    reg     [7:0]                   sm_curr_state;
    reg     [7:0]                   sm_next_state;
    wire                            data_end_flag;

//================================================================================
//
//  INTEGER/GENVAR
//
//================================================================================



//================================================================================
//
//  ASSIGN
//
//================================================================================

    assign  data_end_flag   = (rom_addr == DATA_NUM);
    assign  done_o          = sm_curr_state == SM_DONE_S;

//================================================================================
//
//  CODING
//
//================================================================================

SpiMaster #(
    .CLK_DIVISOR_POWER  (SPI_CLK_DIVISOR_POWER),
    .DATA_WIDTH         (DATA_WIDTH),
    .CPOL               (SPI_CPOL),
    .CPHA               (SPI_CPHA),
    .DATA_DIRECTION     (SPI_DATA_DIRECTION),
    .EN_START_DELAY     (SPI_EN_START_DELAY)
) SpiMaster (
    .clk_i      (clk_i),
    .rst_i      (rst_i),

    .data_i     (rom_data),
    .valid_i    (rom_valid),
    .ready_o    (spi_ready),
    .mosi_o     (mosi_o),
    .sck_o      (sck_o),
    .ss_o       (ss_o)
);

SinglePortRom #(
    .DATA_WIDTH     (DATA_WIDTH), 
    .ADDR_WIDTH     (ROM_ADDR_WIDTH),
    .INIT_FILE_NAME (ROM_INIT_FILE),
    .DATA_BASE      (FILE_DATA_BASE)
) Rom (
    .clk_i  (clk_i),
    .addr_i (rom_addr),
    .q_o    (rom_data)
    );

always @(posedge clk_i or posedge rst_i) begin
    if (rst_i) begin
        sm_curr_state   <= 0;
        rom_addr        <= SM_RST_S;
    end else begin
        sm_curr_state   <= sm_next_state;
        rom_addr        <= rom_addr_next;
    end
end

always @(*) begin
    sm_next_state   = 0;
    rom_addr_next   = rom_addr;
    rom_valid       = 1'b0;
    case(sm_curr_state)
        SM_RST_S        :   begin
            if (enable_i) begin
                sm_next_state   = SM_SEND_DATA_S;
            end else begin
                sm_next_state   = SM_RST_S;
            end
        end

        SM_SEND_DATA_S  :   begin
            rom_valid       = 1'b1;
            sm_next_state   = SM_SEND_DATA_S;
            if (spi_ready) begin
                rom_addr_next   = rom_addr + {{(ROM_ADDR_WIDTH-1){1'b0}}, 1'b1};
                sm_next_state   = SM_READ_DATA_S;
            end
        end

        SM_READ_DATA_S  :   begin
            if (data_end_flag) begin
                sm_next_state   = SM_WAIT_SPI_S;
            end else begin
                sm_next_state   = SM_SEND_DATA_S;
            end
        end

        SM_WAIT_SPI_S   : begin
            if (spi_ready) begin
                sm_next_state   = SM_DONE_S;
            end else begin
                sm_next_state   = SM_WAIT_SPI_S;
            end
        end

        SM_DONE_S       :   begin
            sm_next_state   = SM_DONE_S;
        end

    endcase
end

endmodule