sub ba2bi3 {
	my $ba = pack 'C*', (@_, (0) x (4 - ( @_ % 4 || 4 ) ) );
	my $result = Math::BigInt->new(0);
	my $p  = length($ba) - 4;
	do {
		$result <<= 32; #!4294967296;
		$result += unpack 'V', substr $ba, $p , 4;
	} while ($p-=4) >= 0;
	$result;
}

print ba2bi3( bigint_to_bytearray( Math::BigInt->new('1234567890' x 8) ) );