// OpenRAM SRAM model
// Words: 256
// Word size: 64
// Write size: 8

/* verilator lint_off MULTIDRIVEN */
/* verilator lint_off UNUSED */
module sky130_sram_1rw1r_64x256_8(
// Port 0: RW
    clk0,csb0,web0,wmask0,addr0,din0,dout0,
// Port 1: R
    clk1,csb1,addr1,dout1
  );

  parameter NUM_WMASKS = 8 ;
  parameter DATA_WIDTH = 64 ;
  parameter ADDR_WIDTH = 8 ;
  parameter RAM_DEPTH = 1 << ADDR_WIDTH;
  // FIXME: This delay is arbitrary.
  parameter DELAY = 3 ;
  parameter T_HOLD = 1 ; //Delay to hold dout value after posedge. Value is arbitrary
  input  clk0; // clock
  input  csb0; // active low chip select
  input  web0; // active low write control
  input [NUM_WMASKS-1:0]   wmask0; // write mask
  input [ADDR_WIDTH-1:0]  addr0;
  input [DATA_WIDTH-1:0]  din0;
  output [DATA_WIDTH-1:0] dout0;
  input  clk1; // clock
  input   csb1; // active low chip select
  input [ADDR_WIDTH-1:0]  addr1;
  output [DATA_WIDTH-1:0] dout1;

  reg  csb0_reg;
  reg  web0_reg;
  reg [NUM_WMASKS-1:0]  wmask0_reg;
  reg [ADDR_WIDTH-1:0]  addr0_reg;
  reg [DATA_WIDTH-1:0]  din0_reg;
  reg [DATA_WIDTH-1:0]  dout0;
  reg [DATA_WIDTH-1:0]    mem [0:RAM_DEPTH-1];
  // All inputs are registers
  always @(posedge clk0)
  begin
    csb0_reg <= csb0;
    web0_reg <= web0;
    wmask0_reg <= wmask0;
    addr0_reg <= addr0;
    din0_reg <= din0;
    /*verilator lint_off STMTDLY*/
    dout0 <= 64'bx;
    // if ( !csb0_reg && web0_reg ) 
    //   $display($time," Reading %m addr0=%b dout0=%b",addr0_reg,mem[addr0_reg]);
    // if ( !csb0_reg && !web0_reg )
    //   $display($time," Writing %m addr0=%b din0=%b wmask0=%b",addr0_reg,din0_reg,wmask0_reg);
    /*verilator lint_on STMTDLY*/
  end

  reg  csb1_reg;
  reg [ADDR_WIDTH-1:0]  addr1_reg;
  reg [DATA_WIDTH-1:0]  dout1;

  // All inputs are registers
  always @(posedge clk1)
  begin
    csb1_reg <= csb1;
    addr1_reg <= addr1;
//     if (!csb0 && !web0 && !csb1 && (addr0 == addr1))
//          $display($time," WARNING: Writing and reading addr0=%b and addr1=%b simultaneously!",addr0,addr1);
 //   dout1 <= 64'bx;
//     if ( !csb1_reg ) 
//       $display($time," Reading %m addr1=%b dout1=%b",addr1_reg,mem[addr1_reg]);
  end


  // Memory Write Block Port 0
  // Write Operation : When web0 = 0, csb0 = 0
  always @ (negedge clk0)
  begin : MEM_WRITE0
    if ( !csb0_reg && !web0_reg ) begin
        if (wmask0_reg[0])
                mem[addr0_reg][7:0] <= din0_reg[7:0];
        if (wmask0_reg[1])
                mem[addr0_reg][15:8] <= din0_reg[15:8];
        if (wmask0_reg[2])
                mem[addr0_reg][23:16] <= din0_reg[23:16];
        if (wmask0_reg[3])
                mem[addr0_reg][31:24] <= din0_reg[31:24];
        if (wmask0_reg[4])
                mem[addr0_reg][39:32] <= din0_reg[39:32];
        if (wmask0_reg[5])
                mem[addr0_reg][47:40] <= din0_reg[47:40];
        if (wmask0_reg[6])
                mem[addr0_reg][55:48] <= din0_reg[55:48];
        if (wmask0_reg[7])
                mem[addr0_reg][63:56] <= din0_reg[63:56];
    end
  end

  // Memory Read Block Port 0
  // Read Operation : When web0 = 1, csb0 = 0
  always @ (negedge clk0)
  begin : MEM_READ0
    if (!csb0_reg && web0_reg)
    /*verilator lint_off ASSIGNDLY*/
       dout0 <= #(DELAY) mem[addr0_reg];
    
  end

  // Memory Read Block Port 1
  // Read Operation : When web1 = 1, csb1 = 0
  always @ (negedge clk1)
  begin : MEM_READ1
    if (!csb1_reg)
       dout1 <= #(DELAY) mem[addr1_reg];
  end

endmodule
    /*verilator lint_on ASSIGNDLY*/