use Math::BigInt;

my $switchPortNumber = 2;
# 32 Character hex string from switch
my $hexstring = Math::BigInt->new('0x40000000000000000000000000000000'); 
my $mask = (Math::BigInt->new('0x80000000000000000000000000000000') >> $switchPortNumber);
my $result = ($hexstring & $mask) > 0;