Bitmapper NPM | npm.io

bitmapper

Parse/unparse complex objects to/from a buffer array based on a bit structure;

Setup a structure map by defining the bit size of each property. And then convert it back and forth. The most compact data protocol possible. Perfect for low capacity hardware such as smartcards/rfids or low other band situations.

Currently only supports buffers, numbers and fixed size arrays. Don't expect the unparsed buffer to be the same since undefined and null will be zeros.

Installation

NPM Installation:

npm install bitmapper --save

Usage example

With typescript decorators

class TestItem {
  @value({ size: 10 })
  key: number;
  @value({ size: 5 })
  value: number;
}

class Test {
  //when the type is an array of other type the size is the fixed array length 
  @value({ size: 14, type: TestItem })
  array: TestMixItem[];
  //defaul type is unsigned number
  @value({ size: 10 })
  value: number;
  @value({ size: 46, type: ValueType.buffer })
  buffer: Buffer;
}

const TestMappable = bitMappable(Test); //to create a extension of the class with parse/unparse method;

const obj1 = new TestMappable();
const buffer = obj1.toBitBuffer(); //this will return a fixed size buffer based on the object map.
const obj2 = TestMappable.fromBitBuffer(buffer); //by acessing this static method you can get an instance of the TestMappable object similar to the obj1

Don't need to use the bitMappable class decorator.

const obj1 = new Test();
const buffer = toBitBuffer(obj1);
const obj2 = fromBitBuffer(buffer, { type: Test });

Without any typescript decorators

Also don't need to use any class decorator.

    const obj1 = { value1: 0xF, value2: 0xAA }
    const bitmap = [ { prop: "value1", size: 4, type: ValueType.unsigned }, { prop: "value2", size: 8, type: ValueType.unsigned } ];
    const buffer = toBitBuffer(x, { bitmap });
    const obj2 = fromBitBuffer(buffer, { bitmap });

For more examples and usage, please refer to the Test.