FFI Module

(ffi/align type)

Get the align of an ffi type in bytes.

(ffi/call pointer signature & args)

Call a raw pointer as a function pointer. The function signature specifies how Janet values in `args` are converted to native machine types.

(ffi/close native)

Free a native object. Dereferencing pointers to symbols in the object will have undefined behavior after freeing.

(ffi/context &opt native-path &named map-symbols lazy)

Set the path of the dynamic library to implictly bind, as well as other global state for ease of creating native bindings.

(ffi/defbind name ret-type & body)

Generate bindings for native functions in a convenient manner.

(ffi/free pointer)

Free memory allocated with `ffi/malloc`.

(ffi/jitfn bytes)

Create an abstract type that can be used as the pointer argument to `ffi/call`. The content of `bytes` is architecture specific machine code that will be copied into executable memory.

(ffi/lookup native symbol-name)

Lookup a symbol from a native object. All symbol lookups will return a raw pointer if the symbol is found, else nil.

(ffi/malloc size)

Allocates memory directly using the system memory allocator. Memory allocated in this way must be freed manually! Returns a raw pointer, or nil if size = 0.

(ffi/native &opt path)

Load a shared object or dll from the given path, and do not extract or run any code from it. This is different than `native`, which will run initialization code to get a module table. If `path` is nil, opens the current running binary. Returns a `core/native`.

(ffi/read ffi-type bytes &opt offset)

Parse a native struct out of a buffer and convert it to normal Janet data structures. This function is the inverse of `ffi/write`. `bytes` can also be a raw pointer, although this is unsafe.

(ffi/signature calling-convention ret-type & arg-types)

Create a function signature object that can be used to make calls with raw function pointers.

(ffi/size type)

Get the size of an ffi type in bytes.

(ffi/struct & types)

Create a struct type definition that can be used to pass structs into native functions. 

(ffi/trampoline cc)

Get a native function pointer that can be used as a callback and passed to C libraries. This callback trampoline has the signature `void trampoline(void \*ctx, void \*userdata)` in the given calling convention. This is the only function signature supported. It is up to the programmer to ensure that the `userdata` argument contains a janet function the will be called with one argument, `ctx` which is an opaque pointer. This pointer can be further inspected with `ffi/read`.

(ffi/write ffi-type data &opt buffer)

Append a native tyep to a buffer such as it would appear in memory. This can be used to pass pointers to structs in the ffi, or send C/C++/native structs over the network or to files. Returns a modifed buffer or a new buffer if one is not supplied.