CFunction - ArkFFI

CFunction wraps a raw C function pointer as a callable TypeScript function.

Example

import ffi from 'liblibrary.so';
import { CFunction, FFIType } from 'arkffi';

const handle = ffi.load('libffi_target.so');
const ptr = ffi.getSymbolPtr(handle, 'add');

const add = CFunction({
  args: [FFIType.double, FFIType.double],
  returns: FFIType.double,
  ptr: ptr,
});

add(2.0, 3.0); // → 5.0
add.close();
ffi.close(handle);

Syntax

function CFunction(def: {
  args: string[];
  returns: string;
  ptr: number;
}): {
  (...args: any[]): number;
  close(): void;
};

Parameters

Parameter	Type	Description
`def.args`	`string[]`	C function argument type codes. Supports `FFIType.callback` (auto-extracts `.ptr` from JSCallback)
`def.returns`	`string`	C function return type code
`def.ptr`	`number`	Raw function pointer address

Callback Type Arguments

When an argument type is FFIType.callback ('k'), the JSCallback instance is automatically unwrapped to its .ptr:

let fn = CFunction({
  args: [FFIType.callback, FFIType.int32],
  returns: FFIType.int32,
  ptr: applyPtr,
});
fn(cb, 21); // cb.ptr is automatically used as the first argument

Obtaining Pointers

Use ffi.getSymbolPtr(handle, name):

const handle = ffi.load('lib.so');
const ptr = ffi.getSymbolPtr(handle, 'calculate');
const fn = CFunction({ args: ['i', 'd'], returns: 'd', ptr });
fn(42, 3.14);
fn.close();
ffi.close(handle);

Async Version: `AsyncCFunction`

AsyncCFunction has the same signature as CFunction but returns Promise<number>, executing on a background thread without blocking the main thread.

import { AsyncCFunction, FFIType } from 'arkffi';
import ffi from 'liblibrary.so';

const handle = ffi.load('lib.so');
const ptr = ffi.getSymbolPtr(handle, 'calculate');
const fn = AsyncCFunction({ args: ['i', 'd'], returns: 'd', ptr });

fn(42, 3.14).then((r: number) => {
  console.log(r);
  fn.close();
  ffi.close(handle);
});

Comparison	`CFunction`	`AsyncCFunction`
Returns	`number` (sync)	`Promise<number>` (async)
Blocks main thread	✅ Yes	❌ No