@akamfoad/qr/src/lib/BitBuffer.ts

Fully typed QRCode encoding implementation in JavaScript with no dependencies!

export default class QRBitBuffer {
  buffer: number[];
  length: number;
  constructor() {
    this.buffer = [];
    this.length = 0;
  }

  get(index: number) {
    const bufIndex = Math.floor(index / 8);
    return ((this.buffer[bufIndex] >>> (7 - (index % 8))) & 1) == 1;
  }

  put(num: number, length: number) {
    for (let i = 0; i < length; i++) {
      this.putBit(((num >>> (length - i - 1)) & 1) == 1);
    }
  }

  getLengthInBits() {
    return this.length;
  }

  putBit(bit: boolean) {
    const bufIndex = Math.floor(this.length / 8);
    if (this.buffer.length <= bufIndex) {
      this.buffer.push(0);
    }

    if (bit) {
      this.buffer[bufIndex] |= 0x80 >>> this.length % 8;
    }

    this.length++;
  }
}