C-structure NPM

c-struct

A fast binary data packing & unpacking library for node.js designed for multiplayer games.

What can it do?

8, 16, 24, 32, 40 and 48 bit signed and unsigned integers.
String with length and null-terminated cstrings.
Boolean, nibble, float and double.
Big and little endianness.
Schema based packing and unpacking.
Unpack from buffer to object.
Pack from object to buffer.
Pack with default value if key isn't specified.

Available via npm.
Zero production dependencies.

Installation

npm install c-struct --save

Execute $ node examples/ to see the examples.

Usage

Unpacking

var _ = require('c-struct');

var playerSchema = new _.Schema({
  id: _.type.uint16,
  name: _.type.string(16),
  hp: _.type.uint24,
  exp: _.type.uint32,
  status: _.type.uint8,
  motd: _.type.string(), // null-terminated if no length
  motw: _.type.string(), // cstring if no length
  skills: [{
    id: _.type.uint8,
    name: _.type.string(32),
    secret: _.type.uint40
  }],
  position: {
    x: _.type.uint16,
    y: _.type.uint16
  },
  hash: _.type.uint48
});

// register to cache
_.register('Player', playerSchema);

// object to buffer | this can be on another file
var buf = _.packSync('Player', {
  id: 1,
  name: 'Foobar',
  hp: 1000,
  exp: 88888888,
  status: 100,
  skills: [{
    id: 1,
    name: 'traps of thunder',
    secret: 5151515151
  }, {
    id: 2,
  }, {
    name: 'fatal blow'
  }, {
    id: 3,
    name: 'galvano strike'
  }],
  position: {
    x: 102,
    y: 351
  },
  motd: 'welcome',
  motw: 'weekly',
  hash: 99999999,
});

Packing

var _ = require('c-struct');

var playerSchema = new _.Schema({
  id: _.type.uint16,
  name: _.type.string(16),
  hp: _.type.uint24,
  exp: _.type.uint32,
  status: _.type.uint8,
  motd: _.type.string(), // null-terminated if no length
  motw: _.type.string(), // cstring if no length
  skills: [{
    id: _.type.uint8,
    name: _.type.string(32),
    secret: _.type.uint40
  }],
  position: {
    x: _.type.uint16,
    y: _.type.uint16
  },
  hash: _.type.uint48
});

// register to cache
_.register('Player', playerSchema);

// buffer to object | this can be on another file
var obj = _.unpackSync('Player', BUFFER_HERE);

API

Currently only unsigned values in little endian are supported

_.type.uint8    // unsigned char
_.type.uint16   // unsigned short
_.type.uint24
_.type.uint32   // unsigned long
_.type.uint40
_.type.uint48

You can also specify default values

_.type.u8(9999) // default value 9999
_.type.u16(999) // default value 999
_.type.u24(888) // default value 888
_.type.u32(777) // default value 777
_.type.u40(666) // default value 666
_.type.u48(555) // default value 555