T * ptr
This is syntactic sugar for T value ptr (see ForeignType Pointer) for dereferencing pointers.
T value ptr
i1 : ptr = voidstar address int 5 o1 = 0x7f7a940b8ab0 o1 : ForeignObject of type void*
i2 : int * ptr o2 = 5 o2 : ForeignObject of type int32
The source of this document is in ForeignFunctions.m2:2016:0.