Merge ints

(Note: in c++ value range from >=0 to <= 65535 per value due to 2 of 4 byte of the integer)

= 0 ^ 0 => 0

Split ints

(Note: in c++ value range from >=-2^32-1 to <=2^32-1 (4294967295) per value due to 4 byte integer)

= 0 => 0 0

c++ implementation
php implementation