@foliojs-fork/restructure/src/Number.js

Declaratively encode and decode binary data

const DecodeStream = require('./DecodeStream');

class NumberT {
  constructor(type, endian = 'BE') {
    this.type = type;
    this.endian = endian;
    this.fn = this.type;
    if (this.type[this.type.length - 1] !== '8') {
      this.fn += this.endian;
    }
  }

  size() {
    return DecodeStream.TYPES[this.type];
  }

  decode(stream) {
    return stream[`read${this.fn}`]();
  }

  encode(stream, val) {
    return stream[`write${this.fn}`](val);
  }
}

exports.Number = NumberT;
exports.uint8 = new NumberT('UInt8');
exports.uint16be = (exports.uint16 = new NumberT('UInt16', 'BE'));
exports.uint16le = new NumberT('UInt16', 'LE');
exports.uint24be = (exports.uint24 = new NumberT('UInt24', 'BE'));
exports.uint24le = new NumberT('UInt24', 'LE');
exports.uint32be = (exports.uint32 = new NumberT('UInt32', 'BE'));
exports.uint32le = new NumberT('UInt32', 'LE');
exports.int8 = new NumberT('Int8');
exports.int16be = (exports.int16 = new NumberT('Int16', 'BE'));
exports.int16le = new NumberT('Int16', 'LE');
exports.int24be = (exports.int24 = new NumberT('Int24', 'BE'));
exports.int24le = new NumberT('Int24', 'LE');
exports.int32be = (exports.int32 = new NumberT('Int32', 'BE'));
exports.int32le = new NumberT('Int32', 'LE');
exports.floatbe = (exports.float = new NumberT('Float', 'BE'));
exports.floatle = new NumberT('Float', 'LE');
exports.doublebe = (exports.double = new NumberT('Double', 'BE'));
exports.doublele = new NumberT('Double', 'LE');

class Fixed extends NumberT {
  constructor(size, endian, fracBits = size >> 1) {
    super(`Int${size}`, endian);
    this._point = 1 << fracBits;
  }

  decode(stream) {
    return super.decode(stream) / this._point;
  }

  encode(stream, val) {
    return super.encode(stream, (val * this._point) | 0);
  }
}

exports.Fixed = Fixed;
exports.fixed16be = (exports.fixed16 = new Fixed(16, 'BE'));
exports.fixed16le = new Fixed(16, 'LE');
exports.fixed32be = (exports.fixed32 =new Fixed(32, 'BE'));
exports.fixed32le = new Fixed(32, 'LE');