This macro returns a pointer to the location specified by
alien-expr, which must be either an Alien variable, a use of
deref, a use of slot, or a use of
extern-alien.
This macro converts alien to a new Alien with the specified
new-type. Both types must be an Alien pointer, array or
function type. Note that the result is not eq to the
argument, but does refer to the same data bits.
sap-alien converts sap (a system area pointer
see system-area-pointers) to an Alien value with the specified
type. type is not evaluated.
alien-sap returns the SAP which points to alien-value’s
data.
The type to sap-alien and the type of the alien-value to
alien-sap must some Alien pointer, array or record type.