[Macro]
alien: addr alien-expr
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 (page 
).
[Macro]
alien: cast alien new-type
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.
[Macro]
alien: sap-alien sap type
alien:alien-sap alien-value
sap-alien converts sap (a system area pointer see section 6.5) 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.