It is possible to write a word whose body consists of arbitrary assembly code. The assembly receives parameters and returns values as per the platform's ABI; marshalling and unmarshalling Factor values is taken care of by the C library interface, as with
alien-invoke.
Assembler opcodes are defined in CPU-specific vocabularies:
The combinator for generating arbitrary assembly by calling a quotation at compile time:
alien-assembly ( args... return parameters abi quot -- return... )