wishbone_pkg.vhd

      -- I2C address
      i2c_addr_i : in  std_logic_vector(6 downto 0);

      -- Status outputs
      -- TIP  : Transfer In Progress
      --        '1' when the I2C slave detects a matching I2C address, thus a
      --            transfer is in progress
      --        '0' when idle
      -- ERR  : Error
      --       '1' when the SysMon attempts to access an invalid WB slave
      --       '0' when idle
      -- WDTO : Watchdog timeout (single clock cycle pulse)
      --        '1' -- timeout of watchdog occured
      --        '0' -- when idle
      tip_o      : out std_logic;
      err_p_o    : out std_logic;
      wdto_p_o   : out std_logic;

      -- Wishbone master signals
      wbm_stb_o  : out std_logic;
      wbm_cyc_o  : out std_logic;
      wbm_sel_o  : out std_logic_vector(3 downto 0);
      wbm_we_o   : out std_logic;
      wbm_dat_i  : in  std_logic_vector(31 downto 0);
      wbm_dat_o  : out std_logic_vector(31 downto 0);
      wbm_adr_o  : out std_logic_vector(31 downto 0);
      wbm_ack_i  : in  std_logic;
      wbm_rty_i  : in  std_logic;
      wbm_err_i  : in  std_logic
    );
  end component wb_i2c_bridge;

  ------------------------------------------------------------------------------
  -- MultiBoot component
  ------------------------------------------------------------------------------
  component xwb_xil_multiboot is
    port
    (
      -- Clock and reset input ports
      clk_i   : in  std_logic;
      rst_n_i : in  std_logic;

      -- Wishbone ports
      wbs_i   : in  t_wishbone_slave_in;
      wbs_o   : out t_wishbone_slave_out;

      -- SPI ports
      spi_cs_n_o : out std_logic;
      spi_sclk_o : out std_logic;
      spi_mosi_o : out std_logic;
      spi_miso_i : in  std_logic
    );
  end component xwb_xil_multiboot;

  constant c_xwb_xil_multiboot_sdb : t_sdb_device := (
    abi_class     => x"0000",              -- undocumented device
    abi_ver_major => x"01",
    abi_ver_minor => x"00",
    wbd_endian    => c_sdb_endian_big,
    wbd_width     => x"7",                 -- 8/16/32-bit port granularity
    sdb_component => (
      addr_first  => x"0000000000000000",
      addr_last   => x"000000000000001f",
      product     => (
        vendor_id => x"000000000000CE42",  -- CERN
        device_id => x"11da333d",          -- echo "WB-Xilinx-MultiBoot" | md5sum | cut -c1-8
        version   => x"00000001",
        date      => x"20140313",
        name      => "WB-Xilinx-MultiBoot")));

end wishbone_pkg;

package body wishbone_pkg is
   -- f_wb_wr: processes a write reqest to a slave register with select lines. valid modes are "owr", "set" and "clr"
   function f_wb_wr(pval : std_logic_vector; ival : std_logic_vector; sel : std_logic_vector; mode : string := "owr") return std_logic_vector is
      variable n_sel     : std_logic_vector(pval'range);
      variable n_val     : std_logic_vector(pval'range);
      variable result 	 : std_logic_vector(pval'range);   
   begin
     for i in pval'range loop 
      n_sel(i) := sel((i-pval'low) / 8); -- subtract the low index for when register width > wishbone data width
      n_val(i) := ival(i-pval'low);
     end loop;

     if(mode = "set") then  
      result := pval or (n_val and n_sel);
     elsif (mode = "clr") then
      result := pval and not (n_val and n_sel); 
     else
      result := (pval and not n_sel) or (n_val and n_sel);    
     end if;  
     
     return result;
   end f_wb_wr;
  
  function f_ceil_log2(x : natural) return natural is
  begin
    if x <= 1
    then return 0;
    else return f_ceil_log2((x+1)/2) +1;
    end if;
  end f_ceil_log2;

  function f_sdb_embed_product(product : t_sdb_product)
    return std_logic_vector             -- (319 downto 8)
  is
    variable result : std_logic_vector(319 downto 8);
  begin
    result(319 downto 256) := product.vendor_id;
    result(255 downto 224) := product.device_id;
    result(223 downto 192) := product.version;
    result(191 downto 160) := product.date;
    for i in 0 to 18 loop               -- string to ascii
      result(159-i*8 downto 152-i*8) :=
        std_logic_vector(to_unsigned(character'pos(product.name(i+1)), 8));
    end loop;
    return result;
  end;

  function f_sdb_extract_product(sdb_record : std_logic_vector(319 downto 8))
    return t_sdb_product
  is
    variable result : t_sdb_product;
  begin
    result.vendor_id := sdb_record(319 downto 256);
    result.device_id := sdb_record(255 downto 224);
    result.version   := sdb_record(223 downto 192);
    result.date      := sdb_record(191 downto 160);
    for i in 0 to 18 loop               -- ascii to string
      result.name(i+1) := character'val(to_integer(unsigned(sdb_record(159-i*8 downto 152-i*8))));
    end loop;
    return result;
  end;

  function f_sdb_embed_component(sdb_component : t_sdb_component; address : t_wishbone_address)
    return std_logic_vector             -- (447 downto 8)
  is
    variable result : std_logic_vector(447 downto 8);

    constant first : unsigned(63 downto 0) := unsigned(sdb_component.addr_first);
    constant last  : unsigned(63 downto 0) := unsigned(sdb_component.addr_last);
    variable base  : unsigned(63 downto 0) := (others => '0');
  begin
    base(address'length-1 downto 0) := unsigned(address);

    result(447 downto 384) := std_logic_vector(base);
    result(383 downto 320) := std_logic_vector(base + last - first);
    result(319 downto 8)   := f_sdb_embed_product(sdb_component.product);
    return result;
  end;

  function f_sdb_extract_component(sdb_record : std_logic_vector(447 downto 8))
    return t_sdb_component
  is
    variable result : t_sdb_component;
  begin
    result.addr_first := sdb_record(447 downto 384);
    result.addr_last  := sdb_record(383 downto 320);
    result.product    := f_sdb_extract_product(sdb_record(319 downto 8));
    return result;
  end;

  function f_sdb_embed_device(device : t_sdb_device; address : t_wishbone_address)
    return t_sdb_record
  is
    variable result : t_sdb_record;
  begin
    result(511 downto 496) := device.abi_class;
    result(495 downto 488) := device.abi_ver_major;
    result(487 downto 480) := device.abi_ver_minor;
    result(479 downto 456) := (others => '0');
    result(455)            := device.wbd_endian;
    result(454 downto 452) := (others => '0');
    result(451 downto 448) := device.wbd_width;
    result(447 downto 8)   := f_sdb_embed_component(device.sdb_component, address);
    result(7 downto 0)     := x"01";    -- device
    return result;
  end;

  function f_sdb_extract_device(sdb_record : t_sdb_record)
    return t_sdb_device
  is
    variable result : t_sdb_device;
  begin
    result.abi_class     := sdb_record(511 downto 496);
    result.abi_ver_major := sdb_record(495 downto 488);
    result.abi_ver_minor := sdb_record(487 downto 480);
    result.wbd_endian    := sdb_record(452);
    result.wbd_width     := sdb_record(451 downto 448);
    result.sdb_component := f_sdb_extract_component(sdb_record(447 downto 8));

    assert sdb_record(7 downto 0) = x"01"
      report "Cannot extract t_sdb_device from record of type " & integer'image(to_integer(unsigned(sdb_record(7 downto 0)))) & "."
      severity failure;
    
    return result;
  end;

  function f_sdb_embed_integration(integr : t_sdb_integration)
    return t_sdb_record
  is
    variable result : t_sdb_record;
  begin
    result(511 downto 320) := (others => '0');
    result(319 downto 8)   := f_sdb_embed_product(integr.product);
    result(7 downto 0)     := x"80"; -- integration record
    return result;
  end f_sdb_embed_integration;

  function f_sdb_extract_integration(sdb_record : t_sdb_record)
    return t_sdb_integration
  is
    variable result : t_sdb_integration;
  begin
    result.product := f_sdb_extract_product(sdb_record(319 downto 8));

    assert sdb_record(7 downto 0) = x"80"
    report "Cannot extract t_sdb_integration from record of type " & Integer'image(to_integer(unsigned(sdb_record(7 downto 0)))) & "."
    severity Failure;

    return result;
  end f_sdb_extract_integration;

  function f_sdb_embed_repo_url(url : t_sdb_repo_url)
    return t_sdb_record
  is
    variable result : t_sdb_record;
  begin
    result(511 downto 8) := f_string2svl(url.repo_url);
    result(  7 downto 0) := x"81"; -- repo_url record
    return result;
  end;

  function f_sdb_extract_repo_url(sdb_record : t_sdb_record)
    return t_sdb_repo_url
  is
    variable result : t_sdb_repo_url;
  begin
    result.repo_url     := f_slv2string(sdb_record(511 downto 8));

    assert sdb_record(7 downto 0) = x"81"
    report "Cannot extract t_sdb_repo_url from record of type " & Integer'image(to_integer(unsigned(sdb_record(7 downto 0)))) & "."
    severity Failure;

    return result;
  end;

  function f_sdb_embed_synthesis(syn : t_sdb_synthesis)
    return t_sdb_record
  is
    variable result : t_sdb_record;
  begin
    result(511 downto 384) := f_string2svl(syn.syn_module_name);
    result(383 downto 256) := f_string2bits(syn.syn_commit_id);
    result(255 downto 192) := f_string2svl(syn.syn_tool_name);
    result(191 downto 160) := syn.syn_tool_version;
    result(159 downto 128) := syn.syn_date;
    result(127 downto   8) := f_string2svl(syn.syn_username);
    result(  7 downto   0) := x"82"; -- synthesis record
    return result;
  end;

  function f_sdb_extract_synthesis(sdb_record : t_sdb_record)
    return t_sdb_synthesis
  is
    variable result : t_sdb_synthesis;
  begin
    result.syn_module_name  := f_slv2string(sdb_record(511 downto 384));
    result.syn_commit_id    := f_bits2string(sdb_record(383 downto 256));
    result.syn_tool_name    := f_slv2string(sdb_record(255 downto 192));
    result.syn_tool_version := sdb_record(191 downto 160);
    result.syn_date         := sdb_record(159 downto 128);
    result.syn_username     := f_slv2string(sdb_record(127 downto   8));

    assert sdb_record(7 downto 0) = x"82"
    report "Cannot extract t_sdb_repo_url from record of type " & Integer'image(to_integer(unsigned(sdb_record(7 downto 0)))) & "."
    severity Failure;

    return result;
  end;

  function f_sdb_embed_bridge(bridge : t_sdb_bridge; address : t_wishbone_address)
    return t_sdb_record
  is
    variable result : t_sdb_record;

    constant first : unsigned(63 downto 0) := unsigned(bridge.sdb_component.addr_first);
    constant child : unsigned(63 downto 0) := unsigned(bridge.sdb_child);
    variable base  : unsigned(63 downto 0) := (others => '0');
  begin
    base(address'length-1 downto 0) := unsigned(address);

    result(511 downto 448) := std_logic_vector(base + child - first);
    result(447 downto 8)   := f_sdb_embed_component(bridge.sdb_component, address);
    result(7 downto 0)     := x"02";    -- bridge
    return result;
  end;

  function f_sdb_extract_bridge(sdb_record : t_sdb_record)
    return t_sdb_bridge
  is
    variable result : t_sdb_bridge;
  begin
    result.sdb_child     := sdb_record(511 downto 448);
    result.sdb_component := f_sdb_extract_component(sdb_record(447 downto 8));

    assert sdb_record(7 downto 0) = x"02"
      report "Cannot extract t_sdb_bridge from record of type " & integer'image(to_integer(unsigned(sdb_record(7 downto 0)))) & "."
      severity failure;
    
    return result;
  end;
  
  function f_sdb_auto_device(device : t_sdb_device; enable : boolean := true)
    return t_sdb_record
  is
    constant c_zero  : t_wishbone_address := (others => '0');
    variable v_empty : t_sdb_record := (others => '0');
  begin
    v_empty(7 downto 0) := (others => '1');
    if enable then
      return f_sdb_embed_device(device, c_zero);
    else
      return v_empty;
    end if;
  end f_sdb_auto_device;
  
  function f_sdb_auto_bridge(bridge : t_sdb_bridge; enable : boolean := true)
    return t_sdb_record
  is
    constant c_zero  : t_wishbone_address := (others => '0');
    variable v_empty : t_sdb_record := (others => '0');
  begin
    v_empty(7 downto 0) := (others => '1');
    if enable then
      return f_sdb_embed_bridge(bridge, c_zero);
    else
      return v_empty;
    end if;
  end f_sdb_auto_bridge;
  
  subtype t_usdb_address is unsigned(63 downto 0);
  type t_usdb_address_array is array(natural range <>) of t_usdb_address;
  
  -- We map devices by placing the smallest ones first.
  -- This is guaranteed to pack the maximum number of devices in the smallest space.
  -- If a device has an address != 0, we leave it alone and let the crossbar confirm
  -- that the address does not cause a conflict.
  function f_sdb_auto_layout_helper(records : t_sdb_record_array)
    return t_usdb_address_array
  is
    alias c_records : t_sdb_record_array(records'length-1 downto 0) is records;
    constant c_zero : t_usdb_address := (others => '0');
    
    constant c_used_entries : natural := c_records'length + 1;
    constant c_rom_entries  : natural := 2**f_ceil_log2(c_used_entries);
    constant c_rom_bytes    : natural := c_rom_entries * c_sdb_device_length / 8;
        
    variable v_component : t_sdb_component;
    variable v_sizes     : t_usdb_address_array(c_records'length downto 0);
    variable v_address   : t_usdb_address_array(c_records'length downto 0);
    variable v_map       : std_logic_vector(c_records'length downto 0) := (others => '0');
    variable v_cursor    : unsigned(63 downto 0) := (others => '0');
    variable v_increment : unsigned(63 downto 0) := (others => '0');
  begin
    -- First, extract the length of the devices, ignoring those not to be mapped
    for i in c_records'range loop
      v_component := f_sdb_extract_component(c_records(i)(447 downto 8));
      v_sizes(i)   := unsigned(v_component.addr_last);
      v_address(i) := unsigned(v_component.addr_first);
      
      -- Silently round up to a power of two; the crossbar will give a warning for us
      for j in 62 downto 0 loop
        v_sizes(i)(j) := v_sizes(i)(j+1) or v_sizes(i)(j);
      end loop;
      
      -- Only map devices/bridges at address zero
      if v_address(i) = c_zero then
        case c_records(i)(7 downto 0) is
          when x"01" => v_map(i) := '1';
          when x"02" => v_map(i) := '1';
          when others => null;
        end case;
      end if;
    end loop;
    
    -- Assign the SDB record a spot as well
    v_address(c_records'length) := (others => '0');
    v_sizes(c_records'length) := to_unsigned(c_rom_bytes-1, 64);
    v_map(c_records'length) := '1';
    
    -- Start assigning addresses
    for j in 0 to 63 loop
      v_increment := (others => '0');
      v_increment(j) := '1';
      
      for i in 0 to c_records'length loop
        if v_map(i) = '1' and v_sizes(i)(j) = '0' then
          v_map(i) := '0';
          v_address(i) := v_cursor;
          v_cursor := v_cursor + v_increment;
        end if;
      end loop;
      
      -- Round up to the next required alignment
      if v_cursor(j) = '1' then
        v_cursor := v_cursor + v_increment;
      end if;
    end loop;
    
    return v_address;
  end f_sdb_auto_layout_helper;
  
  function f_sdb_auto_layout(records : t_sdb_record_array)
    return t_sdb_record_array
  is
    alias    c_records : t_sdb_record_array(records'length-1 downto 0) is records;
    variable v_result  : t_sdb_record_array(c_records'range) := c_records;
    constant c_address : t_usdb_address_array := f_sdb_auto_layout_helper(c_records);
    variable v_address : t_wishbone_address;
  begin
    -- Put the addresses into the mapping
    for i in v_result'range loop
      v_address :=  std_logic_vector(c_address(i)(t_wishbone_address'range));

      if c_records(i)(7 downto 0) = x"01" then
        v_result(i) := f_sdb_embed_device(f_sdb_extract_device(v_result(i)), v_address);
      end if;
      if c_records(i)(7 downto 0) = x"02" then
        v_result(i) := f_sdb_embed_bridge(f_sdb_extract_bridge(v_result(i)), v_address);
      end if;
    end loop;
    
    return v_result;
  end f_sdb_auto_layout;
  
  function f_sdb_auto_sdb(records : t_sdb_record_array)
    return t_wishbone_address
  is
    alias    c_records : t_sdb_record_array(records'length-1 downto 0) is records;
    constant c_address : t_usdb_address_array(c_records'length downto 0) := f_sdb_auto_layout_helper(c_records);
  begin
    return std_logic_vector(c_address(c_records'length)(t_wishbone_address'range));
  end f_sdb_auto_sdb;


--**************************************************************************************************************************--
-- START MAT's NEW FUNCTIONS FROM 18th Oct 2013
------------------------------------------------------------------------------------------------------------------------------


   function f_sdb_create_array(g_enum_dev_id    : boolean := false;
                            g_dev_id_offs    : natural := 0;
                            g_enum_dev_name  : boolean := false;
                            g_dev_name_offs  : natural := 0;       
                            device           : t_sdb_device; 
                            instances        : natural := 1) 
   return t_sdb_record_array is
      variable result   : t_sdb_record_array(instances-1 downto 0);  
      variable i,j, pos : natural;
      variable dev, newdev      : t_sdb_device;
      variable serial_no : string(1 to 3);
      variable text_possible : boolean := false; 
   begin
      dev := device;
             
      report "### Creating " & integer'image(instances) & " x " & dev.sdb_component.product.name
      severity note;       
      for i in 0 to instances-1 loop
         newdev := dev;        
         if(g_enum_dev_id) then         
            dev.sdb_component.product.device_id :=  
            std_logic_vector( unsigned(dev.sdb_component.product.device_id) 
                              + to_unsigned(i+g_dev_id_offs, dev.sdb_component.product.device_id'length));        
         end if;
         if(g_enum_dev_name) then         
         -- find end of name
            
            for j in dev.sdb_component.product.name'length downto 1 loop
               if(dev.sdb_component.product.name(j) /= ' ') then               
                  pos := j;                  
                  exit;
               end if;
            end loop;
         -- convert i+g_dev_name_offs to string
            serial_no := f_string_fix_len(integer'image(i+g_dev_name_offs), serial_no'length);
            report "### Now: " & serial_no & " of " & dev.sdb_component.product.name severity note;
         -- check if space is sufficient
            assert (serial_no'length+1 <= dev.sdb_component.product.name'length - pos)
            report "Not enough space in namestring of sdb_device " & dev.sdb_component.product.name
            & " to add serial number " & serial_no & ". Space available " & 
            integer'image(dev.sdb_component.product.name'length-pos-1) & ", required " 
            & integer'image(serial_no'length+1)    
            severity Failure;
         end if;
         if(g_enum_dev_name) then
            newdev.sdb_component.product.name(pos+1) := '_'; 
            for j in 1 to serial_no'length loop
               newdev.sdb_component.product.name(pos+1+j) := serial_no(j);
            end loop;            
         end if;
          
      -- insert
         report "### to: " & newdev.sdb_component.product.name severity note;
         result(i) := f_sdb_embed_device(newdev, (others=>'0'));
      end loop;
      return result;
   end f_sdb_create_array;

   function f_sdb_join_arrays(a : t_sdb_record_array; b : t_sdb_record_array) return t_sdb_record_array is
      variable result   : t_sdb_record_array(a'length+b'length-1 downto 0);  
      variable i : natural;
   begin
      for i in 0 to a'left loop
         result(i) := a(i);
      end loop;
      for i in 0 to b'left loop
         result(i+a'length) := b(i);
      end loop;
      return result;
   end f_sdb_join_arrays;


   function f_sdb_extract_base_addr(sdb_record : t_sdb_record) return std_logic_vector is
   begin
      return sdb_record(447 downto 384);
   end f_sdb_extract_base_addr;

   function f_sdb_extract_end_addr(sdb_record : t_sdb_record) return std_logic_vector is
   begin
      return sdb_record(383 downto 320);
   end f_sdb_extract_end_addr;


   function f_align_addr_offset(offs : unsigned; this_rng : unsigned; prev_rng : unsigned)
   return unsigned is
      variable this_pow, prev_pow   : natural;  
      variable start, env, result : unsigned(63 downto 0) := (others => '0');
   begin
      start(offs'left downto 0) := offs;   
      --calculate address envelopes (next power of 2) for previous and this component and choose the larger one
      this_pow := f_hot_to_bin(std_logic_vector(this_rng)); 
      prev_pow := f_hot_to_bin(std_logic_vector(prev_rng));    
      -- no max(). thank you very much, std_numeric :-/   
      if(this_pow >= prev_pow) then
         env(this_pow) := '1';
      else
         env(prev_pow) := '1';
      end if;
      --round up to the next multiple of the envelope...
      if(prev_rng /= 0) then   
         result := start + env - (start mod env);
      else
         result := start;   --...except for first element, result is start. 
      end if;
      return result;
   end f_align_addr_offset;


 -- generates aligned address map for an sdb_record_array, accepts optional start offset 
   function f_sdb_automap_array(sdb_array : t_sdb_record_array; start_offset : t_wishbone_address := (others => '0'))
   return t_sdb_record_array is
      constant len         : natural := sdb_array'length;
      variable this_rng    : unsigned(63 downto 0) := (others => '0');   
      variable prev_rng    : unsigned(63 downto 0) := (others => '0');   
      variable prev_offs   : unsigned(63 downto 0) := (others => '0');   
      variable this_offs   : unsigned(63 downto 0) := (others => '0');   
      variable device      : t_sdb_device;
      variable bridge      : t_sdb_bridge;  
      variable sdb_type    : std_logic_vector(7 downto 0);
      variable i           : natural;
      variable result      : t_sdb_record_array(sdb_array'length-1 downto 0); -- last 
   begin
   
      prev_offs(start_offset'left downto 0) := unsigned(start_offset);
      --traverse the array   
      for i in 0 to len-1 loop
         -- find the fitting extraction function by evaling the type byte. 
         -- could also use the component, but it's safer to use Wes' embed and extract functions.      
         sdb_type := sdb_array(i)(7 downto 0);
         case sdb_type is
            --device         
            when x"01"  => device      := f_sdb_extract_device(sdb_array(i));
                           this_rng    := unsigned(device.sdb_component.addr_last) - unsigned(device.sdb_component.addr_first);                      
                           this_offs   := f_align_addr_offset(prev_offs, this_rng, prev_rng);
                           result(i)   := f_sdb_embed_device(device, std_logic_vector(this_offs(31 downto 0)));
            --bridge
            when x"02"  => bridge      := f_sdb_extract_bridge(sdb_array(i));
                           this_rng    := unsigned(bridge.sdb_component.addr_last) - unsigned(bridge.sdb_component.addr_first);
                           this_offs   := f_align_addr_offset(prev_offs, this_rng, prev_rng);
                           result(i)   := f_sdb_embed_bridge(bridge, std_logic_vector(this_offs(31 downto 0)) );
            --other
            when others => result(i) := sdb_array(i);   
         end case;
         -- doesnt hurt because this_* doesnt change if its not a device or bridge
         prev_rng    := this_rng;
         prev_offs   := this_offs;
      end loop;
      report "##* " & integer'image(sdb_array'length) & " Elements, last address: " & f_bits2string(std_logic_vector(this_offs+this_rng)) severity Note;
      return result;
   end f_sdb_automap_array;


  -- find place for sdb rom on crossbar and return address. try to put it in an address gap.
   function f_sdb_create_rom_addr(sdb_array : t_sdb_record_array) return t_wishbone_address is
      constant len                  : natural := sdb_array'length;
      constant rom_bytes            : natural := (2**f_ceil_log2(sdb_array'length + 1)) * (c_sdb_device_length / 8);
      variable result               : t_wishbone_address  := (others => '0');
      variable this_base, this_end  : unsigned(63 downto 0)          := (others => '0');    
      variable prev_base, prev_end  : unsigned(63 downto 0)          := (others => '0');
      variable rom_base             : unsigned(63 downto 0)          := (others => '0');
      variable sdb_type             : std_logic_vector(7 downto 0);     
   begin
      --traverse the array   
      for i in 0 to len-1 loop     
         sdb_type := sdb_array(i)(7 downto 0);
         if(sdb_type = x"01" or sdb_type = x"02") then
            -- get         
            this_base := unsigned(f_sdb_extract_base_addr(sdb_array(i)));
            this_end  := unsigned(f_sdb_extract_end_addr(sdb_array(i)));
            if(unsigned(result) = 0) then
               rom_base := f_align_addr_offset(prev_base, to_unsigned(rom_bytes-1, 64), (prev_end-prev_base));
               if(rom_base + to_unsigned(rom_bytes, 64) <= this_base) then
                  result := std_logic_vector(rom_base(t_wishbone_address'left downto 0));
               end if;   
            end if;
            prev_base := this_base;
            prev_end  := this_end;      
         end if;
      end loop;   
      -- if there was no gap to fit the sdb rom, place it at the end   
      if(unsigned(result) = 0) then
            result := std_logic_vector(f_align_addr_offset(this_base, to_unsigned(rom_bytes-1, 64), 
                                       this_end-this_base)(t_wishbone_address'left downto 0));   
      end if;      
      return result;
   end f_sdb_create_rom_addr; 
------------------------------------------------------------------------------------------------------------------------------
-- END MAT's NEW FUNCTIONS FROM  18th Oct 2013
------------------------------------------------------------------------------------------------------------------------------

  function f_xwb_bridge_manual_sdb(
    g_size     : t_wishbone_address;
    g_sdb_addr : t_wishbone_address) return t_sdb_bridge
  is
    variable result : t_sdb_bridge;
  begin
    result.sdb_child                                      := (others => '0');
    result.sdb_child(c_wishbone_address_width-1 downto 0) := g_sdb_addr;

    result.sdb_component.addr_first                                     := (others => '0');
    result.sdb_component.addr_last                                      := (others => '0');
    result.sdb_component.addr_last(c_wishbone_address_width-1 downto 0) := g_size;

    result.sdb_component.product.vendor_id := x"0000000000000651";  -- GSI
    result.sdb_component.product.device_id := x"eef0b198";
    result.sdb_component.product.version   := x"00000001";
    result.sdb_component.product.date      := x"20120511";
    result.sdb_component.product.name      := "WB4-Bridge-GSI     ";

    return result;
  end f_xwb_bridge_manual_sdb;
  
  function f_xwb_bridge_layout_sdb(
    g_wraparound : boolean := true;
    g_layout     : t_sdb_record_array;
    g_sdb_addr   : t_wishbone_address) return t_sdb_bridge
  is
    alias c_layout : t_sdb_record_array(g_layout'length-1 downto 0) is g_layout;

    -- How much space does the ROM need?
    constant c_used_entries : natural := c_layout'length + 1;
    constant c_rom_entries  : natural := 2**f_ceil_log2(c_used_entries);  -- next power of 2
    constant c_sdb_bytes    : natural := c_sdb_device_length / 8;
    constant c_rom_bytes    : natural := c_rom_entries * c_sdb_bytes;
    
    variable result : unsigned(63 downto 0);
    variable sdb_component : t_sdb_component;
  begin
    if not g_wraparound then
      result := (others => '0');
      for i in 0 to c_wishbone_address_width-1 loop
        result(i) := '1';
      end loop;
    else
      -- The ROM will be an addressed slave as well
      result := (others => '0');
      result(c_wishbone_address_width-1 downto 0) := unsigned(g_sdb_addr);
      result := result + to_unsigned(c_rom_bytes, 64) - 1;
      
      for i in c_layout'range loop
        sdb_component := f_sdb_extract_component(c_layout(i)(447 downto 8));
        if unsigned(sdb_component.addr_last) > result then
          result := unsigned(sdb_component.addr_last);
        end if;
      end loop;
      -- round result up to a power of two -1
      for i in 62 downto 0 loop
        result(i) := result(i) or result(i+1);
      end loop;
    end if;
    
    return f_xwb_bridge_manual_sdb(std_logic_vector(result(c_wishbone_address_width-1 downto 0)), g_sdb_addr);
  end f_xwb_bridge_layout_sdb;

  function f_xwb_dpram(g_size : natural) return t_sdb_device
  is
    variable result : t_sdb_device;
  begin
    result.abi_class     := x"0001";    -- RAM device
    result.abi_ver_major := x"01";
    result.abi_ver_minor := x"00";
    result.wbd_width     := x"7";       -- 32/16/8-bit supported
    result.wbd_endian    := c_sdb_endian_big;

    result.sdb_component.addr_first := (others => '0');
    result.sdb_component.addr_last  := std_logic_vector(to_unsigned(g_size*4-1, 64));

    result.sdb_component.product.vendor_id := x"000000000000CE42";  -- CERN
    result.sdb_component.product.device_id := x"66cfeb52";
    result.sdb_component.product.version   := x"00000001";
    result.sdb_component.product.date      := x"20120305";
    result.sdb_component.product.name      := "WB4-BlockRAM       ";

    return result;
  end f_xwb_dpram;

  function f_bits2string(s : std_logic_vector) return string is
    --- extend length to full hex nibble
    variable result : string((s'length+7)/4 downto 1);
    variable s_norm : std_logic_vector(result'length*4-1 downto 0) := (others=>'0');
    variable cut : natural;
    variable nibble: std_logic_vector(3 downto 0);
    constant len : natural := result'length;
  begin
    s_norm(s'length-1 downto 0) := s;
    for i in len-1 downto 0 loop
      nibble := s_norm(i*4+3 downto i*4);
      case nibble is
        when "0000" => result(i+1) := '0';
        when "0001" => result(i+1) := '1';
        when "0010" => result(i+1) := '2';
        when "0011" => result(i+1) := '3';
        when "0100" => result(i+1) := '4';
        when "0101" => result(i+1) := '5';
        when "0110" => result(i+1) := '6';
        when "0111" => result(i+1) := '7';
        when "1000" => result(i+1) := '8';
        when "1001" => result(i+1) := '9';
        when "1010" => result(i+1) := 'a';
        when "1011" => result(i+1) := 'b';
        when "1100" => result(i+1) := 'c';
        when "1101" => result(i+1) := 'd';
        when "1110" => result(i+1) := 'e';
        when "1111" => result(i+1) := 'f';
        when others => result(i+1) := 'X';
      end case;
    end loop;

    -- trim leading 0s
    strip : for i in result'length downto 1 loop
      cut := i;
      exit strip when result(i) /= '0';
    end loop;

    return "0x" & result(cut downto 1);
  end f_bits2string;

  -- Converts string (hex number, without leading 0x) to std_logic_vector
  function f_string2bits(s : string) return std_logic_vector is
    constant len : natural := s'length;
    variable slv : std_logic_vector(s'length*4-1 downto 0);
    variable nibble : std_logic_vector(3 downto 0);
  begin
    for i in 0 to len-1 loop
      case s(i+1) is
        when '0' => nibble := X"0";
        when '1' => nibble := X"1";
        when '2' => nibble := X"2";
        when '3' => nibble := X"3";
        when '4' => nibble := X"4";
        when '5' => nibble := X"5";
        when '6' => nibble := X"6";
        when '7' => nibble := X"7";
        when '8' => nibble := X"8";
        when '9' => nibble := X"9";
        when 'a' => nibble := X"A";
        when 'A' => nibble := X"A";
        when 'b' => nibble := X"B";
        when 'B' => nibble := X"B";
        when 'c' => nibble := X"C";
        when 'C' => nibble := X"C";
        when 'd' => nibble := X"D";
        when 'D' => nibble := X"D";
        when 'e' => nibble := X"E";
        when 'E' => nibble := X"E";
        when 'f' => nibble := X"F";
        when 'F' => nibble := X"F";
        when others => nibble := "XXXX";
      end case;
      slv(((i+1)*4)-1 downto i*4) := nibble;
    end loop;
    return slv;
  end f_string2bits;

  -- Converts string to ascii (std_logic_vector)
  function f_string2svl (s : string) return std_logic_vector is
    constant len : natural := s'length;
    variable slv : std_logic_vector((s'length * 8) - 1 downto 0);
  begin
    for i in 0 to len-1 loop
      slv(slv'high-i*8 downto (slv'high-7)-i*8) :=
        std_logic_vector(to_unsigned(character'pos(s(i+1)), 8));
    end loop;
    return slv;
  end f_string2svl;

  -- Converts ascii (std_logic_vector) to string
  function f_slv2string (slv : std_logic_vector) return string is
    constant len : natural := slv'length;
    variable s : string(1 to slv'length/8);
  begin
    for i in 0 to (len/8)-1 loop
      s(i+1) := character'val(to_integer(unsigned(slv(slv'high-i*8 downto (slv'high-7)-i*8))));
    end loop;
    return s;
  end f_slv2string;

    -- pads a string of unknown length to a given length (useful for integer'image)
  function f_string_fix_len ( s : string; ret_len : natural := 10; fill_char : character := '0' ) return string is
      variable ret_v : string (1 to ret_len);
      constant pad_len : integer := ret_len - s'length ;
      variable pad_v : string (1 to abs(pad_len));
   begin
         if pad_len < 1 then
         ret_v := s(ret_v'range);
      else
         pad_v := (others => fill_char);
         ret_v := pad_v & s;
      end if;
      return ret_v;
   end f_string_fix_len;

   function f_hot_to_bin(x : std_logic_vector) return natural is
      variable rv : natural;
   begin
      rv := 0;
      -- if there are few ones set in _x_ then the most significant will be
      -- translated to bin
      for i in 0 to x'left loop
         if x(i) = '1' then
           rv := i+1;
         end if;
      end loop;
      return rv;
  end function;  

  function f_wb_spi_flash_sdb(g_bits : natural) return t_sdb_device is
    variable result : t_sdb_device := (
      abi_class     => x"0000", -- undocumented device
      abi_ver_major => x"01",
      abi_ver_minor => x"02",
      wbd_endian    => c_sdb_endian_big,
      wbd_width     => x"7", -- 8/16/32-bit port granularity
      sdb_component => (
      addr_first    => x"0000000000000000",
      addr_last     => x"0000000000ffffff",
      product => (
      vendor_id     => x"0000000000000651", -- GSI
      device_id     => x"5cf12a1c",
      version       => x"00000002",
      date          => x"20140417",
      name          => "SPI-FLASH-16M-MMAP ")));
  begin
    result.sdb_component.addr_last := std_logic_vector(to_unsigned(2**g_bits-1, 64));
    return result;
  end f_wb_spi_flash_sdb;
  
end wishbone_pkg;