BeadQR/miniprogram/utils/qrcore/bit-buffer.js

function BitBuffer () {
  this.buffer = []
  this.length = 0
}

BitBuffer.prototype = {

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

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

  getLengthInBits: function () {
    return this.length
  },

  putBit: function (bit) {
    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++
  }
}

module.exports = BitBuffer