procedure TfrmMain.ASCIIStrToHexStr(Str: string; var s: array of byte);
var
  I: Integer;
  value: byte;
begin
  for I := 1 to (Length(Str) div 2) do
  begin
    value := SToI(Str[I * 2 - 1]) * 16 + SToI(Str[I * 2]);
    s[I - 1] := value;
  end;
end;
function TfrmMain.SToI(ch: Char): Integer;
var
  table: array[0..16] of Char;
  I: Integer;
begin
  table[0] := '0'; table[1] := '1'; table[2] := '2'; table[3] := '3';
  table[4] := '4'; table[05] := '5'; table[6] := '6'; table[7] := '7';
  table[8] := '8'; table[9] := '9'; table[10] := 'A'; table[11] := 'B';
  table[12] := 'C'; table[13] := 'D'; table[14] := 'E'; table[15] := 'F';
  table[16] := 'X';
  for I := 0 to 16 do
    if upcase(ch) = table[I] then break;

  SToI := I;
end;