## read the specified number of bytes from buffer, called by the other read_* functions
sub read_buffer {
	my ($self , $user_length) = @_;
	my $length = 1;
	$length = $user_length if $user_length;

	if(($self->index() + $length) > $self->size()) { print "$tag: WARNING: ##### read_buffer(): not enough data left, ignoring request to read $length bytes! #####\n"; return 0; }

	my $val = substr($self->buffer(), $self->index(), $length);
	$self->index($self->index() + $length);

	print "$tag: DEBUG: read_buffer(): read raw data '$val' of length $length, now at $self->{_index} (" . $self->data_left() . " bytes of " . $self->size() . " left)\n";

	return $val;
}

## skips the given number of bytes
sub skip {
	my ($self, $user_length) = @_;
	my $default_length;
	my $length;
	$default_length = 1;

	$length = $default_length;
	$length = $user_length if $user_length;

	$self->index($self->index() + $length);

	return $length;
}