txt_util2.vhd

5阶数字滤波器FIR5

-- TXT_UTIL2.VHD :  TXT_UTIL.VHD from Stefan Doll
-- EXTENDED WITH HEX READ FROM FILE (from ModelTech example)

library ieee;
use ieee.std_logic_1164.all;
use std.textio.all;


package txt_util2 is

    -- prints a message to the screen
    procedure print(text: string);

    -- prints the message when active
    -- useful for debug switches
    procedure print(active: boolean; text: string);

    -- converts std_logic into a character
    function chr(sl: std_logic) return character;

    -- converts std_logic into a string (1 to 1)
    function str(sl: std_logic) return string;

    -- converts std_logic_vector into a string (binary base)
    function str(slv: std_logic_vector) return string;

    -- converts boolean into a string
    function str(b: boolean) return string;

    -- converts an integer into a single character
    -- (can also be used for hex conversion and other bases)
    function chr(int: integer) return character;

    -- converts integer into string using specified base
    function str(int: integer; base: integer) return string;

    -- converts integer to string, using base 10
    function str(int: integer) return string;

    -- convert std_logic_vector into a string in hex format
    function hstr(slv: std_logic_vector) return string;


    -- functions to manipulate strings
    -----------------------------------

    -- convert a character to upper case
    function to_upper(c: character) return character;

    -- convert a character to lower case
    function to_lower(c: character) return character;

    -- convert a string to upper case
    function to_upper(s: string) return string;

    -- convert a string to lower case
    function to_lower(s: string) return string;

   
    
    -- functions to convert strings into other formats
    --------------------------------------------------
    
    -- converts a character into std_logic
    function to_std_logic(c: character) return std_logic; 
    
    -- converts a string into std_logic_vector
    function to_std_logic_vector(s: string) return std_logic_vector; 


  
    -- file I/O
    -----------
       
    -- read variable length string from input file
    procedure str_read(file in_file: TEXT; 
                       res_string: out string);
        
    -- print string to a file and start new line
    procedure print(file out_file: TEXT;
                    new_string: in  string);
    
    -- print character to a file and start new line
    procedure print(file out_file: TEXT;
                    char:       in  character);
                    

    -- extensions from modelsim example
    function slv_to_string(inp : std_logic_vector) return string;

    function string_to_slv(s : string) return std_logic_vector;

    function hex_string_to_slv(s : string) return std_logic_vector;

    procedure skip_white(variable lp : inout line);


end txt_util2;



package body txt_util2 is



   -- prints text to the screen

   procedure print(text: string) is
     variable msg_line: line;
     begin
       write(msg_line, text);
       writeline(output, msg_line);
   end print;




   -- prints text to the screen when active

   procedure print(active: boolean; text: string)  is
     begin
      if active then
         print(text);
      end if;
   end print;


   -- converts std_logic into a character

   function chr(sl: std_logic) return character is
    variable c: character;
    begin
      case sl is
         when 'U' => c:= 'U';
         when 'X' => c:= 'X';
         when '0' => c:= '0';
         when '1' => c:= '1';
         when 'Z' => c:= 'Z';
         when 'W' => c:= 'W';
         when 'L' => c:= 'L';
         when 'H' => c:= 'H';
         when '-' => c:= '-';
      end case;
    return c;
   end chr;



   -- converts std_logic into a string (1 to 1)

   function str(sl: std_logic) return string is
    variable s: string(1 to 1);
    begin
        s(1) := chr(sl);
        return s;
   end str;



   -- converts std_logic_vector into a string (binary base)
   -- (this also takes care of the fact that the range of
   --  a string is natural while a std_logic_vector may
   --  have an integer range)

   function str(slv: std_logic_vector) return string is
     variable result : string (1 to slv'length);
     variable r : integer;
   begin
     r := 1;
     for i in slv'range loop
        result(r) := chr(slv(i));
        r := r + 1;
     end loop;
     return result;
   end str;


   function str(b: boolean) return string is

    begin
       if b then
          return "true";
      else
        return "false";
       end if;
    end str;


   -- converts an integer into a character
   -- for 0 to 9 the obvious mapping is used, higher
   -- values are mapped to the characters A-Z
   -- (this is usefull for systems with base > 10)
   -- (adapted from Steve Vogwell's posting in comp.lang.vhdl)

   function chr(int: integer) return character is
    variable c: character;
   begin
        case int is
          when  0 => c := '0';
          when  1 => c := '1';
          when  2 => c := '2';
          when  3 => c := '3';
          when  4 => c := '4';
          when  5 => c := '5';
          when  6 => c := '6';
          when  7 => c := '7';
          when  8 => c := '8';
          when  9 => c := '9';
          when 10 => c := 'A';
          when 11 => c := 'B';
          when 12 => c := 'C';
          when 13 => c := 'D';
          when 14 => c := 'E';
          when 15 => c := 'F';
          when 16 => c := 'G';
          when 17 => c := 'H';
          when 18 => c := 'I';
          when 19 => c := 'J';
          when 20 => c := 'K';
          when 21 => c := 'L';
          when 22 => c := 'M';
          when 23 => c := 'N';
          when 24 => c := 'O';
          when 25 => c := 'P';
          when 26 => c := 'Q';
          when 27 => c := 'R';
          when 28 => c := 'S';
          when 29 => c := 'T';
          when 30 => c := 'U';
          when 31 => c := 'V';
          when 32 => c := 'W';
          when 33 => c := 'X';
          when 34 => c := 'Y';
          when 35 => c := 'Z';
          when others => c := '?';
        end case;
        return c;
    end chr;



   -- convert integer to string using specified base
   -- (adapted from Steve Vogwell's posting in comp.lang.vhdl)

   function str(int: integer; base: integer) return string is

    variable temp:      string(1 to 10);
    variable num:       integer;
    variable abs_int:   integer;
    variable len:       integer := 1;
    variable power:     integer := 1;

   begin

    -- bug fix for negative numbers
    abs_int := abs(int);

    num     := abs_int;

    while num >= base loop                     -- Determine how many
      len := len + 1;                          -- characters required
      num := num / base;                       -- to represent the
    end loop ;                                 -- number.

    for i in len downto 1 loop                 -- Convert the number to
      temp(i) := chr(abs_int/power mod base);  -- a string starting
      power := power * base;                   -- with the right hand
    end loop ;                                 -- side.

    -- return result and add sign if required
    if int < 0 then
       return '-'& temp(1 to len);
     else
       return temp(1 to len);
    end if;

   end str;


  -- convert integer to string, using base 10
  function str(int: integer) return string is

   begin

    return str(int, 10) ;

   end str;



   -- converts a std_logic_vector into a hex string.
   function hstr(slv: std_logic_vector) return string is
       variable hexlen: integer;
       variable longslv : std_logic_vector(67 downto 0) := (others => '0');
       variable hex : string(1 to 16);
       variable fourbit : std_logic_vector(3 downto 0);
     begin
       hexlen := (slv'left+1)/4;
       if (slv'left+1) mod 4 /= 0 then
         hexlen := hexlen + 1;
       end if;
       longslv(slv'left downto 0) := slv;
       for i in (hexlen -1) downto 0 loop
         fourbit := longslv(((i*4)+3) downto (i*4));
         case fourbit is
           when "0000" => hex(hexlen -I) := '0';
           when "0001" => hex(hexlen -I) := '1';
           when "0010" => hex(hexlen -I) := '2';
           when "0011" => hex(hexlen -I) := '3';
           when "0100" => hex(hexlen -I) := '4';
           when "0101" => hex(hexlen -I) := '5';
           when "0110" => hex(hexlen -I) := '6';
           when "0111" => hex(hexlen -I) := '7';
           when "1000" => hex(hexlen -I) := '8';
           when "1001" => hex(hexlen -I) := '9';
           when "1010" => hex(hexlen -I) := 'A';
           when "1011" => hex(hexlen -I) := 'B';
           when "1100" => hex(hexlen -I) := 'C';
           when "1101" => hex(hexlen -I) := 'D';
           when "1110" => hex(hexlen -I) := 'E';
           when "1111" => hex(hexlen -I) := 'F';
           when "ZZZZ" => hex(hexlen -I) := 'z';
           when "UUUU" => hex(hexlen -I) := 'u';
           when "XXXX" => hex(hexlen -I) := 'x';
           when others => hex(hexlen -I) := '?';
         end case;
       end loop;
       return hex(1 to hexlen);
     end hstr;



   -- functions to manipulate strings
   -----------------------------------


   -- convert a character to upper case

   function to_upper(c: character) return character is

      variable u: character;

    begin

       case c is
        when 'a' => u := 'A';
        when 'b' => u := 'B';
        when 'c' => u := 'C';
        when 'd' => u := 'D';
        when 'e' => u := 'E';
        when 'f' => u := 'F';
        when 'g' => u := 'G';
        when 'h' => u := 'H';
        when 'i' => u := 'I';
        when 'j' => u := 'J';
        when 'k' => u := 'K';
        when 'l' => u := 'L';
        when 'm' => u := 'M';
        when 'n' => u := 'N';
        when 'o' => u := 'O';