(PHP 7 >= 7.4.0, PHP 8)
FFI::memcmp — Compares memory areas
   Compares size bytes from the memory areas ptr1 and
   ptr2. Both ptr1 and ptr2
   can be any native data structures (FFI\CData) or PHP
   strings.
  
ptr1The start of one memory area.
ptr2The start of another memory area.
sizeThe number of bytes to compare.
   Returns < 0 if the contents of the memory area starting at ptr1
   are considered less than the contents of the memory area starting at ptr2,
   > 0 if the contents of the first memory area are considered greater than the second,
   and 0 if they are equal.