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//`include "synthesis-defines.v"
module ram_wb_b3(
                 wb_adr_i, wb_bte_i, wb_cti_i, wb_cyc_i, wb_dat_i, wb_sel_i,
                 wb_stb_i, wb_we_i,

                 wb_ack_o, wb_err_o, wb_rty_o, wb_dat_o,

                 wb_clk_i, wb_rst_i);

   parameter dw = 32;
   parameter aw = 32;

   input [aw-1:0]       wb_adr_i;
   input [1:0]          wb_bte_i;
   input [2:0]          wb_cti_i;
   input                wb_cyc_i;
   input [dw-1:0]       wb_dat_i;
   input [3:0]          wb_sel_i;
   input                wb_stb_i;
   input                wb_we_i;
   
   output               wb_ack_o;
   output               wb_err_o;
   output               wb_rty_o;
   output [dw-1:0]      wb_dat_o;
   
   input                wb_clk_i;
   input                wb_rst_i;

   // Memory parameters
// parameter mem_size_bytes = 32'h0000_5000; // 20KBytes
// parameter mem_adr_width = 15; //(log2(mem_size_bytes));
   parameter mem_size_kbytes = TOK_MEM_SIZE ; // 20KBytes
   parameter mem_adr_width = TOK_MEM_ADR_WIDTH ; //(log2(mem_size_bytes));
   
   parameter bytes_per_dw = (dw/8);
   parameter adr_width_for_num_word_bytes = 2; //(log2(bytes_per_dw))
   parameter mem_words = (mem_size_kbytes * 1024/bytes_per_dw);   

   // synthesis attribute ram_style of mem is block
   reg [dw-1:0]         mem [ 0 : mem_words-1 ]   /* verilator public */ /* synthesis ram_style = no_rw_check */;

   // Register to address internal memory array
   reg [(mem_adr_width-adr_width_for_num_word_bytes)-1:0] adr;
   
   wire [31:0]                     wr_data;

   // Register to indicate if the cycle is a Wishbone B3-registered feedback 
   // type access
   reg                             wb_b3_trans;
   wire                            wb_b3_trans_start, wb_b3_trans_stop;
   
   // Register to use for counting the addresses when doing burst accesses
   reg [mem_adr_width-adr_width_for_num_word_bytes-1:0]  burst_adr_counter;
   reg [2:0]                       wb_cti_i_r;
   reg [1:0]                       wb_bte_i_r;
   wire                            using_burst_adr;
   wire                            burst_access_wrong_wb_adr;

   // Wire to indicate addressing error
   wire                            addr_err;   
   
   
   // Logic to detect if there's a burst access going on
   assign wb_b3_trans_start = ((wb_cti_i == 3'b001)|(wb_cti_i == 3'b010)) & 
                              wb_stb_i & !wb_b3_trans;
   
   assign  wb_b3_trans_stop = ((wb_cti_i == 3'b111) & 
                              wb_stb_i & wb_b3_trans & wb_ack_o) | wb_err_o;
   
   always @(posedge wb_clk_i)
     if (wb_rst_i)
       wb_b3_trans <= 0;
     else if (wb_b3_trans_start)
       wb_b3_trans <= 1;
     else if (wb_b3_trans_stop)
       wb_b3_trans <= 0;

   // Burst address generation logic
   always @(/*AUTOSENSE*/wb_ack_o or wb_b3_trans or wb_b3_trans_start
            or wb_bte_i_r or wb_cti_i_r or wb_adr_i or adr)
     if (wb_b3_trans_start)
       // Kick off burst_adr_counter, this assumes 4-byte words when getting
       // address off incoming Wishbone bus address! 
       // So if dw is no longer 4 bytes, change this!
       burst_adr_counter = wb_adr_i[mem_adr_width-1:2];
     else if ((wb_cti_i_r == 3'b010) & wb_ack_o & wb_b3_trans)
       // Incrementing burst
       begin
          if (wb_bte_i_r == 2'b00) // Linear burst
            burst_adr_counter = adr + 1;
          if (wb_bte_i_r == 2'b01) // 4-beat wrap burst
            burst_adr_counter[1:0] = adr[1:0] + 1;
          if (wb_bte_i_r == 2'b10) // 8-beat wrap burst
            burst_adr_counter[2:0] = adr[2:0] + 1;
          if (wb_bte_i_r == 2'b11) // 16-beat wrap burst
            burst_adr_counter[3:0] = adr[3:0] + 1;
       end // if ((wb_cti_i_r == 3'b010) & wb_ack_o_r)

   always @(posedge wb_clk_i)
     wb_bte_i_r <= wb_bte_i;

   // Register it locally
   always @(posedge wb_clk_i)
     wb_cti_i_r <= wb_cti_i;

   assign using_burst_adr = wb_b3_trans;
   
   assign burst_access_wrong_wb_adr = (using_burst_adr & 
                                       (adr != wb_adr_i[mem_adr_width-1:2]));

   // Address registering logic
   always@(posedge wb_clk_i)
     if(wb_rst_i)
       adr <= 0;
     else if (using_burst_adr)
       adr <= burst_adr_counter;
     else if (wb_cyc_i & wb_stb_i)
       adr <= wb_adr_i[mem_adr_width-1:2];

   /* Memory initialisation.
    If not Verilator model, always do load, otherwise only load when called
    from SystemC testbench.
    */
// synthesis translate_off
   parameter memory_file = "sram.vmem";

`ifdef verilator
   
   task do_readmemh;
      // verilator public
      $readmemh(memory_file, mem);
   endtask // do_readmemh
   
`else
   
   initial
     begin
        $readmemh(memory_file, mem);
     end

`endif // !`ifdef verilator
   
//synthesis translate_on
   
   assign wb_rty_o = 0;

   // mux for data to ram, RMW on part sel != 4'hf
   assign wr_data[31:24] = wb_sel_i[3] ? wb_dat_i[31:24] : wb_dat_o[31:24];
   assign wr_data[23:16] = wb_sel_i[2] ? wb_dat_i[23:16] : wb_dat_o[23:16];
   assign wr_data[15: 8] = wb_sel_i[1] ? wb_dat_i[15: 8] : wb_dat_o[15: 8];
   assign wr_data[ 7: 0] = wb_sel_i[0] ? wb_dat_i[ 7: 0] : wb_dat_o[ 7: 0];
   
   wire ram_we;
   assign ram_we = wb_we_i & wb_ack_o;

   assign wb_dat_o = mem[adr];
    
   // Write logic
   always @ (posedge wb_clk_i)
     begin
        if (ram_we)
          mem[adr] <= wr_data;
     end
   
   // Ack Logic
   reg wb_ack_o_r;

   assign wb_ack_o = wb_ack_o_r & wb_stb_i & 
                     !(burst_access_wrong_wb_adr | addr_err);
   
   always @ (posedge wb_clk_i)
     if (wb_rst_i)
       wb_ack_o_r <= 1'b0;
     else if (wb_cyc_i) // We have bus
       begin
          if (addr_err & wb_stb_i)
            begin
               wb_ack_o_r <= 1;
            end
          else if (wb_cti_i == 3'b000)
            begin
               // Classic cycle acks
               if (wb_stb_i)
                 begin
                    if (!wb_ack_o_r)
                      wb_ack_o_r <= 1;
                    else
                      wb_ack_o_r <= 0;
                 end
            end // if (wb_cti_i == 3'b000)
          else if ((wb_cti_i == 3'b001) | (wb_cti_i == 3'b010))
            begin
               // Increment/constant address bursts
               if (wb_stb_i)
                 wb_ack_o_r <= 1;
               else
                 wb_ack_o_r <= 0;
            end
          else if (wb_cti_i == 3'b111)
            begin
               // End of cycle
               if (!wb_ack_o_r)
                 wb_ack_o_r <= wb_stb_i;
               else
                 wb_ack_o_r <= 0;
            end
       end // if (wb_cyc_i)
     else
       wb_ack_o_r <= 0;


   //
   // Error signal generation
   //
   
   // Error when out of bounds of memory - skip top nibble of address in case
   // this is mapped somewhere other than 0x0.
   assign addr_err  = wb_cyc_i & wb_stb_i & (|wb_adr_i[aw-1-4:mem_adr_width]);  
   
   // OR in other errors here...
   assign wb_err_o =  wb_ack_o_r & wb_stb_i & 
                      (burst_access_wrong_wb_adr | addr_err);

   //
   // Access functions
   //
   
   // Function to access RAM (for use by Verilator).
   function [31:0] get_mem32;
      // verilator public
      input [aw-1:0]            addr;
      get_mem32 = mem[addr];
   endfunction // get_mem32   

   // Function to access RAM (for use by Verilator).
   function [7:0] get_mem8;
      // verilator public
      input [aw-1:0]            addr;
            reg [31:0]          temp_word;
      begin
         temp_word = mem[{addr[aw-1:2],2'd0}];
         // Big endian mapping.
         get_mem8 = (addr[1:0]==2'b00) ? temp_word[31:24] :
                    (addr[1:0]==2'b01) ? temp_word[23:16] :
                    (addr[1:0]==2'b10) ? temp_word[15:8] : temp_word[7:0];
         end
   endfunction // get_mem8   

   // Function to write RAM (for use by Verilator).
   function set_mem32;
      // verilator public
      input [aw-1:0]            addr;
      input [dw-1:0]            data;
      mem[addr] = data;
   endfunction // set_mem32   
   
endmodule // ram_wb_b3