function ChopByteArray(const B: array of Byte; Start, Len: Integer):
  TBytes;
var
  First, Last: TBytes;
begin
  if Start < 0 then
    Start := 0;
  if Len < 0 then
    Len := 0
  else if Start >= Length(B) then
    Len := 0
  else if Start + Len > Length(B) then
    Len := Length(B) - Start;
  First := SliceByteArray(B, 0, Start);
  Last := SliceByteArray(B, Start + Len, Length(B));
  Result := ConcatByteArrays(First, Last);
end;
//delphi/2157