十六进制转字符串

function HexToStr(str: string): string;
  function HexToInt(hex: string): integer;
  var
    i: integer;
    function Ncf(num, f: integer): integer;
    var
      i: integer;
    begin
      Result := 1;
      if f = 0 then exit;
      for i := 1 to f do
        result := result * num;
    end;
    function HexCharToInt(HexToken: char): integer;
    begin
      if HexToken > #97 then
        HexToken := Chr(Ord(HexToken) - 32);
      Result := 0;
      if (HexToken > #47) and (HexToken < #58) then { chars 0....9 }
        Result := Ord(HexToken) - 48
      else if (HexToken > #64) and (HexToken < #71) then { chars A....F }
        Result := Ord(HexToken) - 65 + 10;
    end;
  begin
    result := 0;
    hex := ansiuppercase(trim(hex));
    if hex = '' then
      exit;
    for i := 1 to length(hex) do
      result := result + HexCharToInt(hex[i]) * ncf(16, length(hex) - i);
  end;
var
  s, t: string;
  i, j: integer;
  p: pchar;
begin
  s := '';
  i := 1;
  while i < length(str) do begin
    t := str[i] + str[i + 1];
    s := s + chr(hextoint(t));
    i := i + 2;
  end;
  result := s;
end;