crc16 delphi android

function BinToDec(Str: string): Integer;
var
  Len, Res, i: Integer;
  Error: Boolean;
begin
  Error:=False;
  Len:=Length(Str);
  Res:=0;
  for i:=0 to Len-1 do
    if (Str[i]='0')or(Str[i]='1') then
      Res:=Res+Pow(2, Len-i)*StrToInt(Str[i])
    else
    begin
      Error:=True;
      Break;
    end;
  if Error=True then Result:=0
    else Result:=Res;
end;
//------------------------------------------------------------------------------
function CRC16CCITT(bytes: array of Byte): Word;
const
  polynomial = $1021;
var
  crc: Word;
  I, J: Integer;
  b: Byte;
  bit, c15: Boolean;
begin
  crc := $FFFF;
  for I := 0 to High(bytes) do
  begin
    b := bytes[I];
    for J := 0 to 7 do
    begin
      bit := (((b shr (7-J)) and 1) = 1);
      c15 := (((crc shr 15) and 1) = 1);
      crc := crc shl 1;
      if ((c15 xor bit) <> false) then crc := crc xor polynomial;
    end;
  end;
  Result := crc and $ffff;
end;
//------------------------------------------------------------------------------
function bin2crc16(str: string): string;
var
I:integer;
lengthCount : integer;
crcByteArr : array of Byte;
crcOut : Word;
begin
  lengthCount := Trunc(length(str)/8);
  setlength(crcByteArr , lengthCount );
  for I := 0 to lengthCount-1 do
  begin
    crcByteArr[I] := BinToDec(copy(str, I*8, 8));
  end;
  crcOut := CRC16CCITT(crcByteArr);

  result := crcOut.ToHexString;

end;
//-----------------------------------------------------------------------------------
function HexToBin(Hexadecimal: string): string;
const
  BCD: array [0..15] of string =
    ('0000', '0001', '0010', '0011', '0100', '0101', '0110', '0111',
    '1000', '1001', '1010', '1011', '1100', '1101', '1110', '1111');
var
  i: integer;
begin
  //form2.Memo4.Lines.Add('xin'+Hexadecimal);
  Result := '';
  for i := Length(Hexadecimal) downto 1 do
    Result := BCD[StrToInt('$' + Hexadecimal[i])] + Result;
end;
//---------------------------------------------------------------------------------
function Pow(i, k: Integer): Integer;
var
  j, Count: Integer;
begin
  if k>0 then j:=2
    else j:=1;
  for Count:=1 to k-1 do
    j:=j*2;
  Result:=j;
end;