NodeJS-C interface

Question

NodeJS-C interface

I am trying to figure out how to pass data between a C library and a NodeJS module. Would I be able to do so via the NodeFFI module?

Or will I have to write my own NodeJS addon to develop a C-NodeJS interface?

c
node.js

Answer 1

The node-ffi documentation states:

node-ffi is a Node.js addon for loading and calling dynamic libraries using pure JavaScript. It can be used to create bindings to native libraries without writing any C++ code.

You just need to access libraries as stated in node-ffi and the pass results elsewhere. In their source, they have an example. Assuming they're in the same directory:

File factorial.c:

#include <stdint.h>

uint64_t factorial(int max) {
  int i = max;
  uint64_t result = 1;

  while (i >= 2) {
    result *= i--;
  }

  return result;
}

File factorial.js:

//load the ffi module
var ffi = require('ffi');

//include the function
var libfactorial = ffi.Library('./libfactorial', {
  'factorial': [ 'uint64', [ 'int' ] ]
});

if (process.argv.length < 3) {
  console.log('Arguments: ' + process.argv[0] + ' ' + process.argv[1] + ' <max>');
  process.exit();
};

//usage of the function
var output = libfactorial.factorial(parseInt(process.argv[2]));

console.log('Your output: ' + output);

Using the module, the C file is loaded with this:

var libfactorial = ffi.Library('./libfactorial', {
  'factorial': [ 'uint64', [ 'int' ] ]
});

and then accessed like this:

//process.argv are the command line arguments
var argument = parseInt(process.argv[2]);
var output = libfactorial.factorial(argument);