module sirv_mrom # (
    parameter AW = 12,
    parameter DW = 32,
    parameter DP = 1024
)(
  input  [AW-1:2] rom_addr, 
  output [DW-1:0] rom_dout  
  );
        

  wire [31:0] mask_rom [0:DP-1];// 4KB = 1KW 

  assign rom_dout = mask_rom[rom_addr]; 

  genvar i;
  generate 
   if(1) begin: jump_to_ram_gen
       // Just jump to the ITCM base address 
      for (i=0;i<1024;i=i+1) begin: rom_gen
          if(i==0) begin: rom0_gen
              assign mask_rom[i] = 32'h7ffff297; //auipc   t0, 0x7ffff
          end
          else if(i==1) begin: rom1_gen
              assign mask_rom[i] = 32'h00028067; //jr      t0
          end
          else begin: rom_non01_gen
              assign mask_rom[i] = 32'h00000000; 
          end
      end
   end
   else begin: jump_to_non_ram_gen


    // This is the freedom bootrom version, put here have a try
    //  The actual executed trace is as below:
       // CYC: 8615 PC:00001000 IR:0100006f DASM: j       pc + 0x10         
       // CYC: 8618 PC:00001010 IR:204002b7 DASM: lui     t0, 0x20400       xpr[5] = 0x20400000
       // CYC: 8621 PC:00001014 IR:00028067 DASM: jr      t0                

       // The 20400000 is the flash address
         //MEMORY
         //{
         //  flash (rxai!w) : ORIGIN = 0x20400000, LENGTH = 512M
         //  ram (wxa!ri) : ORIGIN = 0x80000000, LENGTH = 16K
         //}


    for (i=0;i<1024;i=i+1) begin: rom_gen
        if(i==0) begin: rom0_gen
            assign mask_rom[i] = 32'h100006f;
        end
        else if(i==1) begin: rom1_gen
            assign mask_rom[i] = 32'h13;
        end
        else if(i==2) begin: rom1_gen
            assign mask_rom[i] = 32'h13;
        end
        else if(i==3) begin: rom1_gen
            assign mask_rom[i] = 32'h6661;// our config code
        end
        else if(i==4) begin: rom1_gen
            //assign mask_rom[i] = 32'h204002b7;
            assign mask_rom[i] = 32'h20400000 | 32'h000002b7;
        end
        else if(i==5) begin: rom1_gen
            assign mask_rom[i] = 32'h28067;
        end
        else begin: rom_non01_gen
            assign mask_rom[i] = 32'h00000000; 
        end
    end
   
  // In the https://github.com/sifive/freedom/blob/master/bootrom/xip/xip.S
  //  ASM code is as below:
     //  //  // See LICENSE for license details.
     //// Execute in place
     //// Jump directly to XIP_TARGET_ADDR
     //
     //  .text
     //  .option norvc
     //  .globl _start
     //_start:
     //  j 1f
     //  nop
     //  nop
     //#ifdef CONFIG_STRING
     //  .word cfg_string
     //#else
     //  .word 0  // Filled in by GenerateBootROM in Chisel
     //#endif
     //
     //1:
     //  li t0, XIP_TARGET_ADDR
     //  jr t0
     //
     //  .section .rodata
     //#ifdef CONFIG_STRING
     //cfg_string:
     //  .incbin CONFIG_STRING
     //#endif
   end

  endgenerate
endmodule