wishbone_pkg.vhd

        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;
      if s'ascending then
        slv(slv'length-(i*4)-1 downto slv'length-(i+1)*4) := nibble;
      else
        slv(((i+1)*4)-1 downto i*4) := nibble;
      end if;
    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'; justify_right : boolean := true ) 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);
         if justify_right then
           ret_v := pad_v & s;
         else
           ret_v := s & pad_v ;
         end if;
      end if;
      return ret_v;
   end f_string_fix_len;

   -- do not synthesize
   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;