buffer-es6.mjs

var lookup = [];
var revLookup = [];
var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array;
var inited = false;
function init() {
  inited = true;
  var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
  for (var i = 0, len = code.length; i < len; ++i) {
    lookup[i] = code[i];
    revLookup[code.charCodeAt(i)] = i;
  }

  revLookup['-'.charCodeAt(0)] = 62;
  revLookup['_'.charCodeAt(0)] = 63;
}

function toByteArray(b64) {
  if (!inited) {
    init();
  }
  var i, j, l, tmp, placeHolders, arr;
  var len = b64.length;

  if (len % 4 > 0) {
    throw new Error('Invalid string. Length must be a multiple of 4');
  }

  // the number of equal signs (place holders)
  // if there are two placeholders, than the two characters before it
  // represent one byte
  // if there is only one, then the three characters before it represent 2 bytes
  // this is just a cheap hack to not do indexOf twice
  placeHolders = b64[len - 2] === '=' ? 2 : b64[len - 1] === '=' ? 1 : 0;

  // base64 is 4/3 + up to two characters of the original data
  arr = new Arr((len * 3) / 4 - placeHolders);

  // if there are placeholders, only get up to the last complete 4 chars
  l = placeHolders > 0 ? len - 4 : len;

  var L = 0;

  for (i = 0, j = 0; i < l; i += 4, j += 3) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 18) |
      (revLookup[b64.charCodeAt(i + 1)] << 12) |
      (revLookup[b64.charCodeAt(i + 2)] << 6) |
      revLookup[b64.charCodeAt(i + 3)];
    arr[L++] = (tmp >> 16) & 0xff;
    arr[L++] = (tmp >> 8) & 0xff;
    arr[L++] = tmp & 0xff;
  }

  if (placeHolders === 2) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 2) |
      (revLookup[b64.charCodeAt(i + 1)] >> 4);
    arr[L++] = tmp & 0xff;
  } else if (placeHolders === 1) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 10) |
      (revLookup[b64.charCodeAt(i + 1)] << 4) |
      (revLookup[b64.charCodeAt(i + 2)] >> 2);
    arr[L++] = (tmp >> 8) & 0xff;
    arr[L++] = tmp & 0xff;
  }

  return arr;
}

function tripletToBase64(num) {
  return (
    lookup[(num >> 18) & 0x3f] +
    lookup[(num >> 12) & 0x3f] +
    lookup[(num >> 6) & 0x3f] +
    lookup[num & 0x3f]
  );
}

function encodeChunk(uint8, start, end) {
  var tmp;
  var output = [];
  for (var i = start; i < end; i += 3) {
    tmp = (uint8[i] << 16) + (uint8[i + 1] << 8) + uint8[i + 2];
    output.push(tripletToBase64(tmp));
  }
  return output.join('');
}

function fromByteArray(uint8) {
  if (!inited) {
    init();
  }
  var tmp;
  var len = uint8.length;
  var extraBytes = len % 3; // if we have 1 byte left, pad 2 bytes
  var output = '';
  var parts = [];
  var maxChunkLength = 16383; // must be multiple of 3

  // go through the array every three bytes, we'll deal with trailing stuff later
  for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
    parts.push(
      encodeChunk(
        uint8,
        i,
        i + maxChunkLength > len2 ? len2 : i + maxChunkLength
      )
    );
  }

  // pad the end with zeros, but make sure to not forget the extra bytes
  if (extraBytes === 1) {
    tmp = uint8[len - 1];
    output += lookup[tmp >> 2];
    output += lookup[(tmp << 4) & 0x3f];
    output += '==';
  } else if (extraBytes === 2) {
    tmp = (uint8[len - 2] << 8) + uint8[len - 1];
    output += lookup[tmp >> 10];
    output += lookup[(tmp >> 4) & 0x3f];
    output += lookup[(tmp << 2) & 0x3f];
    output += '=';
  }

  parts.push(output);

  return parts.join('');
}

function read(buffer, offset, isLE, mLen, nBytes) {
  var e, m;
  var eLen = nBytes * 8 - mLen - 1;
  var eMax = (1 << eLen) - 1;
  var eBias = eMax >> 1;
  var nBits = -7;
  var i = isLE ? nBytes - 1 : 0;
  var d = isLE ? -1 : 1;
  var s = buffer[offset + i];

  i += d;

  e = s & ((1 << -nBits) - 1);
  s >>= -nBits;
  nBits += eLen;
  for (; nBits > 0; e = e * 256 + buffer[offset + i], i += d, nBits -= 8) {}

  m = e & ((1 << -nBits) - 1);
  e >>= -nBits;
  nBits += mLen;
  for (; nBits > 0; m = m * 256 + buffer[offset + i], i += d, nBits -= 8) {}

  if (e === 0) {
    e = 1 - eBias;
  } else if (e === eMax) {
    return m ? NaN : (s ? -1 : 1) * Infinity;
  } else {
    m = m + Math.pow(2, mLen);
    e = e - eBias;
  }
  return (s ? -1 : 1) * m * Math.pow(2, e - mLen);
}

function write(buffer, value, offset, isLE, mLen, nBytes) {
  var e, m, c;
  var eLen = nBytes * 8 - mLen - 1;
  var eMax = (1 << eLen) - 1;
  var eBias = eMax >> 1;
  var rt = mLen === 23 ? Math.pow(2, -24) - Math.pow(2, -77) : 0;
  var i = isLE ? 0 : nBytes - 1;
  var d = isLE ? 1 : -1;
  var s = value < 0 || (value === 0 && 1 / value < 0) ? 1 : 0;

  value = Math.abs(value);

  if (isNaN(value) || value === Infinity) {
    m = isNaN(value) ? 1 : 0;
    e = eMax;
  } else {
    e = Math.floor(Math.log(value) / Math.LN2);
    if (value * (c = Math.pow(2, -e)) < 1) {
      e--;
      c *= 2;
    }
    if (e + eBias >= 1) {
      value += rt / c;
    } else {
      value += rt * Math.pow(2, 1 - eBias);
    }
    if (value * c >= 2) {
      e++;
      c /= 2;
    }

    if (e + eBias >= eMax) {
      m = 0;
      e = eMax;
    } else if (e + eBias >= 1) {
      m = (value * c - 1) * Math.pow(2, mLen);
      e = e + eBias;
    } else {
      m = value * Math.pow(2, eBias - 1) * Math.pow(2, mLen);
      e = 0;
    }
  }

  for (
    ;
    mLen >= 8;
    buffer[offset + i] = m & 0xff, i += d, m /= 256, mLen -= 8
  ) {}

  e = (e << mLen) | m;
  eLen += mLen;
  for (
    ;
    eLen > 0;
    buffer[offset + i] = e & 0xff, i += d, e /= 256, eLen -= 8
  ) {}

  buffer[offset + i - d] |= s * 128;
}

var toString = {}.toString;

var isArray =
  Array.isArray ||
  function (arr) {
    return toString.call(arr) == '[object Array]';
  };

/*!
 * The buffer module from node.js, for the browser.
 *
 * @author   Feross Aboukhadijeh <feross@feross.org> <http://feross.org>
 * @license  MIT
 */

export var INSPECT_MAX_BYTES = 50;

/**
 * If `Buffer.TYPED_ARRAY_SUPPORT`:
 *   === true    Use Uint8Array implementation (fastest)
 *   === false   Use Object implementation (most compatible, even IE6)
 *
 * Browsers that support typed arrays are IE 10+, Firefox 4+, Chrome 7+, Safari 5.1+,
 * Opera 11.6+, iOS 4.2+.
 *
 * Due to various browser bugs, sometimes the Object implementation will be used even
 * when the browser supports typed arrays.
 *
 * Note:
 *
 *   - Firefox 4-29 lacks support for adding new properties to `Uint8Array` instances,
 *     See: https://bugzilla.mozilla.org/show_bug.cgi?id=695438.
 *
 *   - Chrome 9-10 is missing the `TypedArray.prototype.subarray` function.
 *
 *   - IE10 has a broken `TypedArray.prototype.subarray` function which returns arrays of
 *     incorrect length in some situations.
 * We detect these buggy browsers and set `Buffer.TYPED_ARRAY_SUPPORT` to `false` so they
 * get the Object implementation, which is slower but behaves correctly.
 */
const win = typeof window === 'undefined' ? global : window;
Buffer.TYPED_ARRAY_SUPPORT =
  win.TYPED_ARRAY_SUPPORT !== undefined ? win.TYPED_ARRAY_SUPPORT : true;

/*
 * Export kMaxLength after typed array support is determined.
 */
var _kMaxLength = getKMaxLength();
export const kMaxLength = _kMaxLength;

function getKMaxLength() {
  return Buffer.TYPED_ARRAY_SUPPORT ? 0x7fffffff : 0x3fffffff;
}

function createBuffer(that, length) {
  if (getKMaxLength() < length) {
    throw new RangeError('Invalid typed array length');
  }
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    // Return an augmented `Uint8Array` instance, for best performance
    that = new Uint8Array(length);
    that.__proto__ = Buffer.prototype;
  } else {
    // Fallback: Return an object instance of the Buffer class
    if (that === null) {
      that = new Buffer(length);
    }
    that.length = length;
  }

  return that;
}

/**
 * The Buffer constructor returns instances of `Uint8Array` that have their
 * prototype changed to `Buffer.prototype`. Furthermore, `Buffer` is a subclass of
 * `Uint8Array`, so the returned instances will have all the node `Buffer` methods
 * and the `Uint8Array` methods. Square bracket notation works as expected -- it
 * returns a single octet.
 *
 * The `Uint8Array` prototype remains unmodified.
 */

export function Buffer(arg, encodingOrOffset, length) {
  if (!Buffer.TYPED_ARRAY_SUPPORT && !(this instanceof Buffer)) {
    return new Buffer(arg, encodingOrOffset, length);
  }

  // Common case.
  if (typeof arg === 'number') {
    if (typeof encodingOrOffset === 'string') {
      throw new Error(
        'If encoding is specified then the first argument must be a string'
      );
    }
    return allocUnsafe(this, arg);
  }
  return from(this, arg, encodingOrOffset, length);
}

Buffer.poolSize = 8192; // not used by this implementation

// TODO: Legacy, not needed anymore. Remove in next major version.
Buffer._augment = function (arr) {
  arr.__proto__ = Buffer.prototype;
  return arr;
};

function from(that, value, encodingOrOffset, length) {
  if (typeof value === 'number') {
    throw new TypeError('"value" argument must not be a number');
  }

  if (typeof ArrayBuffer !== 'undefined' && value instanceof ArrayBuffer) {
    return fromArrayBuffer(that, value, encodingOrOffset, length);
  }

  if (typeof value === 'string') {
    return fromString(that, value, encodingOrOffset);
  }

  return fromObject(that, value);
}

/**
 * Functionally equivalent to Buffer(arg, encoding) but throws a TypeError
 * if value is a number.
 * Buffer.from(str[, encoding])
 * Buffer.from(array)
 * Buffer.from(buffer)
 * Buffer.from(arrayBuffer[, byteOffset[, length]])
 **/
Buffer.from = function (value, encodingOrOffset, length) {
  return from(null, value, encodingOrOffset, length);
};

if (Buffer.TYPED_ARRAY_SUPPORT) {
  Buffer.prototype.__proto__ = Uint8Array.prototype;
  Buffer.__proto__ = Uint8Array;
}

function assertSize(size) {
  if (typeof size !== 'number') {
    throw new TypeError('"size" argument must be a number');
  } else if (size < 0) {
    throw new RangeError('"size" argument must not be negative');
  }
}

function alloc(that, size, fill, encoding) {
  assertSize(size);
  if (size <= 0) {
    return createBuffer(that, size);
  }
  if (fill !== undefined) {
    // Only pay attention to encoding if it's a string. This
    // prevents accidentally sending in a number that would
    // be interpretted as a start offset.
    return typeof encoding === 'string'
      ? createBuffer(that, size).fill(fill, encoding)
      : createBuffer(that, size).fill(fill);
  }
  return createBuffer(that, size);
}

/**
 * Creates a new filled Buffer instance.
 * alloc(size[, fill[, encoding]])
 **/
Buffer.alloc = function (size, fill, encoding) {
  return alloc(null, size, fill, encoding);
};

function allocUnsafe(that, size) {
  assertSize(size);
  that = createBuffer(that, size < 0 ? 0 : checked(size) | 0);
  if (!Buffer.TYPED_ARRAY_SUPPORT) {
    for (var i = 0; i < size; ++i) {
      that[i] = 0;
    }
  }
  return that;
}

/**
 * Equivalent to Buffer(num), by default creates a non-zero-filled Buffer instance.
 * */
Buffer.allocUnsafe = function (size) {
  return allocUnsafe(null, size);
};
/**
 * Equivalent to SlowBuffer(num), by default creates a non-zero-filled Buffer instance.
 */
Buffer.allocUnsafeSlow = function (size) {
  return allocUnsafe(null, size);
};

function fromString(that, string, encoding) {
  if (typeof encoding !== 'string' || encoding === '') {
    encoding = 'utf8';
  }

  if (!Buffer.isEncoding(encoding)) {
    throw new TypeError('"encoding" must be a valid string encoding');
  }

  var length = byteLength(string, encoding) | 0;
  that = createBuffer(that, length);

  var actual = that.write(string, encoding);

  if (actual !== length) {
    // Writing a hex string, for example, that contains invalid characters will
    // cause everything after the first invalid character to be ignored. (e.g.
    // 'abxxcd' will be treated as 'ab')
    that = that.slice(0, actual);
  }

  return that;
}

function fromArrayLike(that, array) {
  var length = array.length < 0 ? 0 : checked(array.length) | 0;
  that = createBuffer(that, length);
  for (var i = 0; i < length; i += 1) {
    that[i] = array[i] & 255;
  }
  return that;
}

function fromArrayBuffer(that, array, byteOffset, length) {
  array.byteLength; // this throws if `array` is not a valid ArrayBuffer

  if (byteOffset < 0 || array.byteLength < byteOffset) {
    throw new RangeError("'offset' is out of bounds");
  }

  if (array.byteLength < byteOffset + (length || 0)) {
    throw new RangeError("'length' is out of bounds");
  }

  if (byteOffset === undefined && length === undefined) {
    array = new Uint8Array(array);
  } else if (length === undefined) {
    array = new Uint8Array(array, byteOffset);
  } else {
    array = new Uint8Array(array, byteOffset, length);
  }

  if (Buffer.TYPED_ARRAY_SUPPORT) {
    // Return an augmented `Uint8Array` instance, for best performance
    that = array;
    that.__proto__ = Buffer.prototype;
  } else {
    // Fallback: Return an object instance of the Buffer class
    that = fromArrayLike(that, array);
  }
  return that;
}

function fromObject(that, obj) {
  if (internalIsBuffer(obj)) {
    var len = checked(obj.length) | 0;
    that = createBuffer(that, len);

    if (that.length === 0) {
      return that;
    }

    obj.copy(that, 0, 0, len);
    return that;
  }

  if (obj) {
    if (
      (typeof ArrayBuffer !== 'undefined' &&
        obj.buffer instanceof ArrayBuffer) ||
      'length' in obj
    ) {
      if (typeof obj.length !== 'number' || isnan(obj.length)) {
        return createBuffer(that, 0);
      }
      return fromArrayLike(that, obj);
    }

    if (obj.type === 'Buffer' && isArray(obj.data)) {
      return fromArrayLike(that, obj.data);
    }
  }

  throw new TypeError(
    'First argument must be a string, Buffer, ArrayBuffer, Array, or array-like object.'
  );
}

function checked(length) {
  // Note: cannot use `length < kMaxLength()` here because that fails when
  // length is NaN (which is otherwise coerced to zero.)
  if (length >= getKMaxLength()) {
    throw new RangeError(
      'Attempt to allocate Buffer larger than maximum ' +
        'size: 0x' +
        getKMaxLength().toString(16) +
        ' bytes'
    );
  }
  return length | 0;
}

export function SlowBuffer(length) {
  if (+length != length) {
    // eslint-disable-line eqeqeq
    length = 0;
  }
  return Buffer.alloc(+length);
}
Buffer.isBuffer = isBuffer;
function internalIsBuffer(b) {
  return !!(b != null && b._isBuffer);
}

Buffer.compare = function compare(a, b) {
  if (!internalIsBuffer(a) || !internalIsBuffer(b)) {
    throw new TypeError('Arguments must be Buffers');
  }

  if (a === b) return 0;

  var x = a.length;
  var y = b.length;

  for (var i = 0, len = Math.min(x, y); i < len; ++i) {
    if (a[i] !== b[i]) {
      x = a[i];
      y = b[i];
      break;
    }
  }

  if (x < y) return -1;
  if (y < x) return 1;
  return 0;
};

Buffer.isEncoding = function isEncoding(encoding) {
  switch (String(encoding).toLowerCase()) {
    case 'hex':
    case 'utf8':
    case 'utf-8':
    case 'ascii':
    case 'latin1':
    case 'binary':
    case 'base64':
    case 'ucs2':
    case 'ucs-2':
    case 'utf16le':
    case 'utf-16le':
      return true;
    default:
      return false;
  }
};

Buffer.concat = function concat(list, length) {
  if (!isArray(list)) {
    throw new TypeError('"list" argument must be an Array of Buffers');
  }

  if (list.length === 0) {
    return Buffer.alloc(0);
  }

  var i;
  if (length === undefined) {
    length = 0;
    for (i = 0; i < list.length; ++i) {
      length += list[i].length;
    }
  }

  var buffer = Buffer.allocUnsafe(length);
  var pos = 0;
  for (i = 0; i < list.length; ++i) {
    var buf = list[i];
    if (!internalIsBuffer(buf)) {
      throw new TypeError('"list" argument must be an Array of Buffers');
    }
    buf.copy(buffer, pos);
    pos += buf.length;
  }
  return buffer;
};

function byteLength(string, encoding) {
  if (internalIsBuffer(string)) {
    return string.length;
  }
  if (
    typeof ArrayBuffer !== 'undefined' &&
    typeof ArrayBuffer.isView === 'function' &&
    (ArrayBuffer.isView(string) || string instanceof ArrayBuffer)
  ) {
    return string.byteLength;
  }
  if (typeof string !== 'string') {
    string = '' + string;
  }

  var len = string.length;
  if (len === 0) return 0;

  // Use a for loop to avoid recursion
  var loweredCase = false;
  for (;;) {
    switch (encoding) {
      case 'ascii':
      case 'latin1':
      case 'binary':
        return len;
      case 'utf8':
      case 'utf-8':
      case undefined:
        return utf8ToBytes(string).length;
      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return len * 2;
      case 'hex':
        return len >>> 1;
      case 'base64':
        return base64ToBytes(string).length;
      default:
        if (loweredCase) return utf8ToBytes(string).length; // assume utf8
        encoding = ('' + encoding).toLowerCase();
        loweredCase = true;
    }
  }
}
Buffer.byteLength = byteLength;

function slowToString(encoding, start, end) {
  var loweredCase = false;

  // No need to verify that "this.length <= MAX_UINT32" since it's a read-only
  // property of a typed array.

  // This behaves neither like String nor Uint8Array in that we set start/end
  // to their upper/lower bounds if the value passed is out of range.
  // undefined is handled specially as per ECMA-262 6th Edition,
  // Section 13.3.3.7 Runtime Semantics: KeyedBindingInitialization.
  if (start === undefined || start < 0) {
    start = 0;
  }
  // Return early if start > this.length. Done here to prevent potential uint32
  // coercion fail below.
  if (start > this.length) {
    return '';
  }

  if (end === undefined || end > this.length) {
    end = this.length;
  }

  if (end <= 0) {
    return '';
  }

  // Force coersion to uint32. This will also coerce falsey/NaN values to 0.
  end >>>= 0;
  start >>>= 0;

  if (end <= start) {
    return '';
  }

  if (!encoding) encoding = 'utf8';

  while (true) {
    switch (encoding) {
      case 'hex':
        return hexSlice(this, start, end);

      case 'utf8':
      case 'utf-8':
        return utf8Slice(this, start, end);

      case 'ascii':
        return asciiSlice(this, start, end);

      case 'latin1':
      case 'binary':
        return latin1Slice(this, start, end);

      case 'base64':
        return base64Slice(this, start, end);

      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return utf16leSlice(this, start, end);

      default:
        if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding);
        encoding = (encoding + '').toLowerCase();
        loweredCase = true;
    }
  }
}

// The property is used by `Buffer.isBuffer` and `is-buffer` (in Safari 5-7) to detect
// Buffer instances.
Buffer.prototype._isBuffer = true;

function swap(b, n, m) {
  var i = b[n];
  b[n] = b[m];
  b[m] = i;
}

Buffer.prototype.swap16 = function swap16() {
  var len = this.length;
  if (len % 2 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 16-bits');
  }
  for (var i = 0; i < len; i += 2) {
    swap(this, i, i + 1);
  }
  return this;
};

Buffer.prototype.swap32 = function swap32() {
  var len = this.length;
  if (len % 4 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 32-bits');
  }
  for (var i = 0; i < len; i += 4) {
    swap(this, i, i + 3);
    swap(this, i + 1, i + 2);
  }
  return this;
};

Buffer.prototype.swap64 = function swap64() {
  var len = this.length;
  if (len % 8 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 64-bits');
  }
  for (var i = 0; i < len; i += 8) {
    swap(this, i, i + 7);
    swap(this, i + 1, i + 6);
    swap(this, i + 2, i + 5);
    swap(this, i + 3, i + 4);
  }
  return this;
};

Buffer.prototype.toString = function toString() {
  var length = this.length | 0;
  if (length === 0) return '';
  if (arguments.length === 0) return utf8Slice(this, 0, length);
  return slowToString.apply(this, arguments);
};

Buffer.prototype.equals = function equals(b) {
  if (!internalIsBuffer(b)) throw new TypeError('Argument must be a Buffer');
  if (this === b) return true;
  return Buffer.compare(this, b) === 0;
};

Buffer.prototype.inspect = function inspect() {
  var str = '';
  var max = INSPECT_MAX_BYTES;
  if (this.length > 0) {
    str = this.toString('hex', 0, max).match(/.{2}/g).join(' ');
    if (this.length > max) str += ' ... ';
  }
  return '<Buffer ' + str + '>';
};

Buffer.prototype.compare = function compare(
  target,
  start,
  end,
  thisStart,
  thisEnd
) {
  if (!internalIsBuffer(target)) {
    throw new TypeError('Argument must be a Buffer');
  }

  if (start === undefined) {
    start = 0;
  }
  if (end === undefined) {
    end = target ? target.length : 0;
  }
  if (thisStart === undefined) {
    thisStart = 0;
  }
  if (thisEnd === undefined) {
    thisEnd = this.length;
  }

  if (
    start < 0 ||
    end > target.length ||
    thisStart < 0 ||
    thisEnd > this.length
  ) {
    throw new RangeError('out of range index');
  }

  if (thisStart >= thisEnd && start >= end) {
    return 0;
  }
  if (thisStart >= thisEnd) {
    return -1;
  }
  if (start >= end) {
    return 1;
  }

  start >>>= 0;
  end >>>= 0;
  thisStart >>>= 0;
  thisEnd >>>= 0;

  if (this === target) return 0;

  var x = thisEnd - thisStart;
  var y = end - start;
  var len = Math.min(x, y);

  var thisCopy = this.slice(thisStart, thisEnd);
  var targetCopy = target.slice(start, end);

  for (var i = 0; i < len; ++i) {
    if (thisCopy[i] !== targetCopy[i]) {
      x = thisCopy[i];
      y = targetCopy[i];
      break;
    }
  }

  if (x < y) return -1;
  if (y < x) return 1;
  return 0;
};

// Finds either the first index of `val` in `buffer` at offset >= `byteOffset`,
// OR the last index of `val` in `buffer` at offset <= `byteOffset`.
//
// Arguments:
// - buffer - a Buffer to search
// - val - a string, Buffer, or number
// - byteOffset - an index into `buffer`; will be clamped to an int32
// - encoding - an optional encoding, relevant is val is a string
// - dir - true for indexOf, false for lastIndexOf
function bidirectionalIndexOf(buffer, val, byteOffset, encoding, dir) {
  // Empty buffer means no match
  if (buffer.length === 0) return -1;

  // Normalize byteOffset
  if (typeof byteOffset === 'string') {
    encoding = byteOffset;
    byteOffset = 0;
  } else if (byteOffset > 0x7fffffff) {
    byteOffset = 0x7fffffff;
  } else if (byteOffset < -0x80000000) {
    byteOffset = -0x80000000;
  }
  byteOffset = +byteOffset; // Coerce to Number.
  if (isNaN(byteOffset)) {
    // byteOffset: it it's undefined, null, NaN, "foo", etc, search whole buffer
    byteOffset = dir ? 0 : buffer.length - 1;
  }

  // Normalize byteOffset: negative offsets start from the end of the buffer
  if (byteOffset < 0) byteOffset = buffer.length + byteOffset;
  if (byteOffset >= buffer.length) {
    if (dir) return -1;
    else byteOffset = buffer.length - 1;
  } else if (byteOffset < 0) {
    if (dir) byteOffset = 0;
    else return -1;
  }

  // Normalize val
  if (typeof val === 'string') {
    val = Buffer.from(val, encoding);
  }

  // Finally, search either indexOf (if dir is true) or lastIndexOf
  if (internalIsBuffer(val)) {
    // Special case: looking for empty string/buffer always fails
    if (val.length === 0) {
      return -1;
    }
    return arrayIndexOf(buffer, val, byteOffset, encoding, dir);
  } else if (typeof val === 'number') {
    val = val & 0xff; // Search for a byte value [0-255]
    if (
      Buffer.TYPED_ARRAY_SUPPORT &&
      typeof Uint8Array.prototype.indexOf === 'function'
    ) {
      if (dir) {
        return Uint8Array.prototype.indexOf.call(buffer, val, byteOffset);
      } else {
        return Uint8Array.prototype.lastIndexOf.call(buffer, val, byteOffset);
      }
    }
    return arrayIndexOf(buffer, [val], byteOffset, encoding, dir);
  }

  throw new TypeError('val must be string, number or Buffer');
}

function arrayIndexOf(arr, val, byteOffset, encoding, dir) {
  var indexSize = 1;
  var arrLength = arr.length;
  var valLength = val.length;

  if (encoding !== undefined) {
    encoding = String(encoding).toLowerCase();
    if (
      encoding === 'ucs2' ||
      encoding === 'ucs-2' ||
      encoding === 'utf16le' ||
      encoding === 'utf-16le'
    ) {
      if (arr.length < 2 || val.length < 2) {
        return -1;
      }
      indexSize = 2;
      arrLength /= 2;
      valLength /= 2;
      byteOffset /= 2;
    }
  }

  function read(buf, i) {
    if (indexSize === 1) {
      return buf[i];
    } else {
      return buf.readUInt16BE(i * indexSize);
    }
  }

  var i;
  if (dir) {
    var foundIndex = -1;
    for (i = byteOffset; i < arrLength; i++) {
      if (read(arr, i) === read(val, foundIndex === -1 ? 0 : i - foundIndex)) {
        if (foundIndex === -1) foundIndex = i;
        if (i - foundIndex + 1 === valLength) return foundIndex * indexSize;
      } else {
        if (foundIndex !== -1) i -= i - foundIndex;
        foundIndex = -1;
      }
    }
  } else {
    if (byteOffset + valLength > arrLength) byteOffset = arrLength - valLength;
    for (i = byteOffset; i >= 0; i--) {
      var found = true;
      for (var j = 0; j < valLength; j++) {
        if (read(arr, i + j) !== read(val, j)) {
          found = false;
          break;
        }
      }
      if (found) return i;
    }
  }

  return -1;
}

Buffer.prototype.includes = function includes(val, byteOffset, encoding) {
  return this.indexOf(val, byteOffset, encoding) !== -1;
};

Buffer.prototype.indexOf = function indexOf(val, byteOffset, encoding) {
  return bidirectionalIndexOf(this, val, byteOffset, encoding, true);
};

Buffer.prototype.lastIndexOf = function lastIndexOf(val, byteOffset, encoding) {
  return bidirectionalIndexOf(this, val, byteOffset, encoding, false);
};

function hexWrite(buf, string, offset, length) {
  offset = Number(offset) || 0;
  var remaining = buf.length - offset;
  if (!length) {
    length = remaining;
  } else {
    length = Number(length);
    if (length > remaining) {
      length = remaining;
    }
  }

  // must be an even number of digits
  var strLen = string.length;
  if (strLen % 2 !== 0) throw new TypeError('Invalid hex string');

  if (length > strLen / 2) {
    length = strLen / 2;
  }
  for (var i = 0; i < length; ++i) {
    var parsed = parseInt(string.substr(i * 2, 2), 16);
    if (isNaN(parsed)) return i;
    buf[offset + i] = parsed;
  }
  return i;
}

function utf8Write(buf, string, offset, length) {
  return blitBuffer(
    utf8ToBytes(string, buf.length - offset),
    buf,
    offset,
    length
  );
}

function asciiWrite(buf, string, offset, length) {
  return blitBuffer(asciiToBytes(string), buf, offset, length);
}

function latin1Write(buf, string, offset, length) {
  return asciiWrite(buf, string, offset, length);
}

function base64Write(buf, string, offset, length) {
  return blitBuffer(base64ToBytes(string), buf, offset, length);
}

function ucs2Write(buf, string, offset, length) {
  return blitBuffer(
    utf16leToBytes(string, buf.length - offset),
    buf,
    offset,
    length
  );
}

Buffer.prototype.write = function write(string, offset, length, encoding) {
  // Buffer#write(string)
  if (offset === undefined) {
    encoding = 'utf8';
    length = this.length;
    offset = 0;
    // Buffer#write(string, encoding)
  } else if (length === undefined && typeof offset === 'string') {
    encoding = offset;
    length = this.length;
    offset = 0;
    // Buffer#write(string, offset[, length][, encoding])
  } else if (isFinite(offset)) {
    offset = offset | 0;
    if (isFinite(length)) {
      length = length | 0;
      if (encoding === undefined) encoding = 'utf8';
    } else {
      encoding = length;
      length = undefined;
    }
    // legacy write(string, encoding, offset, length) - remove in v0.13
  } else {
    throw new Error(
      'Buffer.write(string, encoding, offset[, length]) is no longer supported'
    );
  }

  var remaining = this.length - offset;
  if (length === undefined || length > remaining) length = remaining;

  if (
    (string.length > 0 && (length < 0 || offset < 0)) ||
    offset > this.length
  ) {
    throw new RangeError('Attempt to write outside buffer bounds');
  }

  if (!encoding) encoding = 'utf8';

  var loweredCase = false;
  for (;;) {
    switch (encoding) {
      case 'hex':
        return hexWrite(this, string, offset, length);

      case 'utf8':
      case 'utf-8':
        return utf8Write(this, string, offset, length);

      case 'ascii':
        return asciiWrite(this, string, offset, length);

      case 'latin1':
      case 'binary':
        return latin1Write(this, string, offset, length);

      case 'base64':
        // Warning: maxLength not taken into account in base64Write
        return base64Write(this, string, offset, length);

      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return ucs2Write(this, string, offset, length);

      default:
        if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding);
        encoding = ('' + encoding).toLowerCase();
        loweredCase = true;
    }
  }
};

Buffer.prototype.toJSON = function toJSON() {
  return {
    type: 'Buffer',
    data: Array.prototype.slice.call(this._arr || this, 0),
  };
};

function base64Slice(buf, start, end) {
  if (start === 0 && end === buf.length) {
    return fromByteArray(buf);
  } else {
    return fromByteArray(buf.slice(start, end));
  }
}

function utf8Slice(buf, start, end) {
  end = Math.min(buf.length, end);
  var res = [];

  var i = start;
  while (i < end) {
    var firstByte = buf[i];
    var codePoint = null;
    var bytesPerSequence =
      firstByte > 0xef ? 4 : firstByte > 0xdf ? 3 : firstByte > 0xbf ? 2 : 1;

    if (i + bytesPerSequence <= end) {
      var secondByte, thirdByte, fourthByte, tempCodePoint;

      switch (bytesPerSequence) {
        case 1:
          if (firstByte < 0x80) {
            codePoint = firstByte;
          }
          break;
        case 2:
          secondByte = buf[i + 1];
          if ((secondByte & 0xc0) === 0x80) {
            tempCodePoint = ((firstByte & 0x1f) << 0x6) | (secondByte & 0x3f);
            if (tempCodePoint > 0x7f) {
              codePoint = tempCodePoint;
            }
          }
          break;
        case 3:
          secondByte = buf[i + 1];
          thirdByte = buf[i + 2];
          if ((secondByte & 0xc0) === 0x80 && (thirdByte & 0xc0) === 0x80) {
            tempCodePoint =
              ((firstByte & 0xf) << 0xc) |
              ((secondByte & 0x3f) << 0x6) |
              (thirdByte & 0x3f);
            if (
              tempCodePoint > 0x7ff &&
              (tempCodePoint < 0xd800 || tempCodePoint > 0xdfff)
            ) {
              codePoint = tempCodePoint;
            }
          }
          break;
        case 4:
          secondByte = buf[i + 1];
          thirdByte = buf[i + 2];
          fourthByte = buf[i + 3];
          if (
            (secondByte & 0xc0) === 0x80 &&
            (thirdByte & 0xc0) === 0x80 &&
            (fourthByte & 0xc0) === 0x80
          ) {
            tempCodePoint =
              ((firstByte & 0xf) << 0x12) |
              ((secondByte & 0x3f) << 0xc) |
              ((thirdByte & 0x3f) << 0x6) |
              (fourthByte & 0x3f);
            if (tempCodePoint > 0xffff && tempCodePoint < 0x110000) {
              codePoint = tempCodePoint;
            }
          }
      }
    }

    if (codePoint === null) {
      // we did not generate a valid codePoint so insert a
      // replacement char (U+FFFD) and advance only 1 byte
      codePoint = 0xfffd;
      bytesPerSequence = 1;
    } else if (codePoint > 0xffff) {
      // encode to utf16 (surrogate pair dance)
      codePoint -= 0x10000;
      res.push(((codePoint >>> 10) & 0x3ff) | 0xd800);
      codePoint = 0xdc00 | (codePoint & 0x3ff);
    }

    res.push(codePoint);
    i += bytesPerSequence;
  }

  return decodeCodePointsArray(res);
}

// Based on http://stackoverflow.com/a/22747272/680742, the browser with
// the lowest limit is Chrome, with 0x10000 args.
// We go 1 magnitude less, for safety
var MAX_ARGUMENTS_LENGTH = 0x1000;

function decodeCodePointsArray(codePoints) {
  var len = codePoints.length;
  if (len <= MAX_ARGUMENTS_LENGTH) {
    return String.fromCharCode.apply(String, codePoints); // avoid extra slice()
  }

  // Decode in chunks to avoid "call stack size exceeded".
  var res = '';
  var i = 0;
  while (i < len) {
    res += String.fromCharCode.apply(
      String,
      codePoints.slice(i, (i += MAX_ARGUMENTS_LENGTH))
    );
  }
  return res;
}

function asciiSlice(buf, start, end) {
  var ret = '';
  end = Math.min(buf.length, end);

  for (var i = start; i < end; ++i) {
    ret += String.fromCharCode(buf[i] & 0x7f);
  }
  return ret;
}

function latin1Slice(buf, start, end) {
  var ret = '';
  end = Math.min(buf.length, end);

  for (var i = start; i < end; ++i) {
    ret += String.fromCharCode(buf[i]);
  }
  return ret;
}

function hexSlice(buf, start, end) {
  var len = buf.length;

  if (!start || start < 0) start = 0;
  if (!end || end < 0 || end > len) end = len;

  var out = '';
  for (var i = start; i < end; ++i) {
    out += toHex(buf[i]);
  }
  return out;
}

function utf16leSlice(buf, start, end) {
  var bytes = buf.slice(start, end);
  var res = '';
  for (var i = 0; i < bytes.length; i += 2) {
    res += String.fromCharCode(bytes[i] + bytes[i + 1] * 256);
  }
  return res;
}

Buffer.prototype.slice = function slice(start, end) {
  var len = this.length;
  start = ~~start;
  end = end === undefined ? len : ~~end;

  if (start < 0) {
    start += len;
    if (start < 0) start = 0;
  } else if (start > len) {
    start = len;
  }

  if (end < 0) {
    end += len;
    if (end < 0) end = 0;
  } else if (end > len) {
    end = len;
  }

  if (end < start) end = start;

  var newBuf;
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    newBuf = this.subarray(start, end);
    newBuf.__proto__ = Buffer.prototype;
  } else {
    var sliceLen = end - start;
    newBuf = new Buffer(sliceLen, undefined);
    for (var i = 0; i < sliceLen; ++i) {
      newBuf[i] = this[i + start];
    }
  }

  return newBuf;
};

/*
 * Need to make sure that buffer isn't trying to write out of bounds.
 */
function checkOffset(offset, ext, length) {
  if (offset % 1 !== 0 || offset < 0)
    throw new RangeError('offset is not uint');
  if (offset + ext > length)
    throw new RangeError('Trying to access beyond buffer length');
}

Buffer.prototype.readUIntLE = function readUIntLE(
  offset,
  byteLength,
  noAssert
) {
  offset = offset | 0;
  byteLength = byteLength | 0;
  if (!noAssert) checkOffset(offset, byteLength, this.length);

  var val = this[offset];
  var mul = 1;
  var i = 0;
  while (++i < byteLength && (mul *= 0x100)) {
    val += this[offset + i] * mul;
  }

  return val;
};

Buffer.prototype.readUIntBE = function readUIntBE(
  offset,
  byteLength,
  noAssert
) {
  offset = offset | 0;
  byteLength = byteLength | 0;
  if (!noAssert) {
    checkOffset(offset, byteLength, this.length);
  }

  var val = this[offset + --byteLength];
  var mul = 1;
  while (byteLength > 0 && (mul *= 0x100)) {
    val += this[offset + --byteLength] * mul;
  }

  return val;
};

Buffer.prototype.readUInt8 = function readUInt8(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 1, this.length);
  return this[offset];
};

Buffer.prototype.readUInt16LE = function readUInt16LE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 2, this.length);
  return this[offset] | (this[offset + 1] << 8);
};

Buffer.prototype.readUInt16BE = function readUInt16BE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 2, this.length);
  return (this[offset] << 8) | this[offset + 1];
};

Buffer.prototype.readUInt32LE = function readUInt32LE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 4, this.length);

  return (
    (this[offset] | (this[offset + 1] << 8) | (this[offset + 2] << 16)) +
    this[offset + 3] * 0x1000000
  );
};

Buffer.prototype.readUInt32BE = function readUInt32BE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 4, this.length);

  return (
    this[offset] * 0x1000000 +
    ((this[offset + 1] << 16) | (this[offset + 2] << 8) | this[offset + 3])
  );
};

Buffer.prototype.readIntLE = function readIntLE(offset, byteLength, noAssert) {
  offset = offset | 0;
  byteLength = byteLength | 0;
  if (!noAssert) checkOffset(offset, byteLength, this.length);

  var val = this[offset];
  var mul = 1;
  var i = 0;
  while (++i < byteLength && (mul *= 0x100)) {
    val += this[offset + i] * mul;
  }
  mul *= 0x80;

  if (val >= mul) val -= Math.pow(2, 8 * byteLength);

  return val;
};

Buffer.prototype.readIntBE = function readIntBE(offset, byteLength, noAssert) {
  offset = offset | 0;
  byteLength = byteLength | 0;
  if (!noAssert) checkOffset(offset, byteLength, this.length);

  var i = byteLength;
  var mul = 1;
  var val = this[offset + --i];
  while (i > 0 && (mul *= 0x100)) {
    val += this[offset + --i] * mul;
  }
  mul *= 0x80;

  if (val >= mul) val -= Math.pow(2, 8 * byteLength);

  return val;
};

Buffer.prototype.readInt8 = function readInt8(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 1, this.length);
  if (!(this[offset] & 0x80)) return this[offset];
  return (0xff - this[offset] + 1) * -1;
};

Buffer.prototype.readInt16LE = function readInt16LE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 2, this.length);
  var val = this[offset] | (this[offset + 1] << 8);
  return val & 0x8000 ? val | 0xffff0000 : val;
};

Buffer.prototype.readInt16BE = function readInt16BE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 2, this.length);
  var val = this[offset + 1] | (this[offset] << 8);
  return val & 0x8000 ? val | 0xffff0000 : val;
};

Buffer.prototype.readInt32LE = function readInt32LE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 4, this.length);

  return (
    this[offset] |
    (this[offset + 1] << 8) |
    (this[offset + 2] << 16) |
    (this[offset + 3] << 24)
  );
};

Buffer.prototype.readInt32BE = function readInt32BE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 4, this.length);

  return (
    (this[offset] << 24) |
    (this[offset + 1] << 16) |
    (this[offset + 2] << 8) |
    this[offset + 3]
  );
};

Buffer.prototype.readFloatLE = function readFloatLE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 4, this.length);
  return read(this, offset, true, 23, 4);
};

Buffer.prototype.readFloatBE = function readFloatBE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 4, this.length);
  return read(this, offset, false, 23, 4);
};

Buffer.prototype.readDoubleLE = function readDoubleLE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 8, this.length);
  return read(this, offset, true, 52, 8);
};

Buffer.prototype.readDoubleBE = function readDoubleBE(offset, noAssert) {
  if (!noAssert) checkOffset(offset, 8, this.length);
  return read(this, offset, false, 52, 8);
};

function checkInt(buf, value, offset, ext, max, min) {
  if (!internalIsBuffer(buf))
    throw new TypeError('"buffer" argument must be a Buffer instance');
  if (value > max || value < min)
    throw new RangeError('"value" argument is out of bounds');
  if (offset + ext > buf.length) throw new RangeError('Index out of range');
}

Buffer.prototype.writeUIntLE = function writeUIntLE(
  value,
  offset,
  byteLength,
  noAssert
) {
  value = +value;
  offset = offset | 0;
  byteLength = byteLength | 0;
  if (!noAssert) {
    var maxBytes = Math.pow(2, 8 * byteLength) - 1;
    checkInt(this, value, offset, byteLength, maxBytes, 0);
  }

  var mul = 1;
  var i = 0;
  this[offset] = value & 0xff;
  while (++i < byteLength && (mul *= 0x100)) {
    this[offset + i] = (value / mul) & 0xff;
  }

  return offset + byteLength;
};

Buffer.prototype.writeUIntBE = function writeUIntBE(
  value,
  offset,
  byteLength,
  noAssert
) {
  value = +value;
  offset = offset | 0;
  byteLength = byteLength | 0;
  if (!noAssert) {
    var maxBytes = Math.pow(2, 8 * byteLength) - 1;
    checkInt(this, value, offset, byteLength, maxBytes, 0);
  }

  var i = byteLength - 1;
  var mul = 1;
  this[offset + i] = value & 0xff;
  while (--i >= 0 && (mul *= 0x100)) {
    this[offset + i] = (value / mul) & 0xff;
  }

  return offset + byteLength;
};

Buffer.prototype.writeUInt8 = function writeUInt8(value, offset, noAssert) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 1, 0xff, 0);
  if (!Buffer.TYPED_ARRAY_SUPPORT) value = Math.floor(value);
  this[offset] = value & 0xff;
  return offset + 1;
};

function objectWriteUInt16(buf, value, offset, littleEndian) {
  if (value < 0) value = 0xffff + value + 1;
  for (var i = 0, j = Math.min(buf.length - offset, 2); i < j; ++i) {
    buf[offset + i] =
      (value & (0xff << (8 * (littleEndian ? i : 1 - i)))) >>>
      ((littleEndian ? i : 1 - i) * 8);
  }
}

Buffer.prototype.writeUInt16LE = function writeUInt16LE(
  value,
  offset,
  noAssert
) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 2, 0xffff, 0);
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    this[offset] = value & 0xff;
    this[offset + 1] = value >>> 8;
  } else {
    objectWriteUInt16(this, value, offset, true);
  }
  return offset + 2;
};

Buffer.prototype.writeUInt16BE = function writeUInt16BE(
  value,
  offset,
  noAssert
) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 2, 0xffff, 0);
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    this[offset] = value >>> 8;
    this[offset + 1] = value & 0xff;
  } else {
    objectWriteUInt16(this, value, offset, false);
  }
  return offset + 2;
};

function objectWriteUInt32(buf, value, offset, littleEndian) {
  if (value < 0) value = 0xffffffff + value + 1;
  for (var i = 0, j = Math.min(buf.length - offset, 4); i < j; ++i) {
    buf[offset + i] = (value >>> ((littleEndian ? i : 3 - i) * 8)) & 0xff;
  }
}

Buffer.prototype.writeUInt32LE = function writeUInt32LE(
  value,
  offset,
  noAssert
) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 4, 0xffffffff, 0);
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    this[offset + 3] = value >>> 24;
    this[offset + 2] = value >>> 16;
    this[offset + 1] = value >>> 8;
    this[offset] = value & 0xff;
  } else {
    objectWriteUInt32(this, value, offset, true);
  }
  return offset + 4;
};

Buffer.prototype.writeUInt32BE = function writeUInt32BE(
  value,
  offset,
  noAssert
) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 4, 0xffffffff, 0);
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    this[offset] = value >>> 24;
    this[offset + 1] = value >>> 16;
    this[offset + 2] = value >>> 8;
    this[offset + 3] = value & 0xff;
  } else {
    objectWriteUInt32(this, value, offset, false);
  }
  return offset + 4;
};

Buffer.prototype.writeIntLE = function writeIntLE(
  value,
  offset,
  byteLength,
  noAssert
) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) {
    var limit = Math.pow(2, 8 * byteLength - 1);

    checkInt(this, value, offset, byteLength, limit - 1, -limit);
  }

  var i = 0;
  var mul = 1;
  var sub = 0;
  this[offset] = value & 0xff;
  while (++i < byteLength && (mul *= 0x100)) {
    if (value < 0 && sub === 0 && this[offset + i - 1] !== 0) {
      sub = 1;
    }
    this[offset + i] = (((value / mul) >> 0) - sub) & 0xff;
  }

  return offset + byteLength;
};

Buffer.prototype.writeIntBE = function writeIntBE(
  value,
  offset,
  byteLength,
  noAssert
) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) {
    var limit = Math.pow(2, 8 * byteLength - 1);

    checkInt(this, value, offset, byteLength, limit - 1, -limit);
  }

  var i = byteLength - 1;
  var mul = 1;
  var sub = 0;
  this[offset + i] = value & 0xff;
  while (--i >= 0 && (mul *= 0x100)) {
    if (value < 0 && sub === 0 && this[offset + i + 1] !== 0) {
      sub = 1;
    }
    this[offset + i] = (((value / mul) >> 0) - sub) & 0xff;
  }

  return offset + byteLength;
};

Buffer.prototype.writeInt8 = function writeInt8(value, offset, noAssert) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 1, 0x7f, -0x80);
  if (!Buffer.TYPED_ARRAY_SUPPORT) value = Math.floor(value);
  if (value < 0) value = 0xff + value + 1;
  this[offset] = value & 0xff;
  return offset + 1;
};

Buffer.prototype.writeInt16LE = function writeInt16LE(value, offset, noAssert) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000);
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    this[offset] = value & 0xff;
    this[offset + 1] = value >>> 8;
  } else {
    objectWriteUInt16(this, value, offset, true);
  }
  return offset + 2;
};

Buffer.prototype.writeInt16BE = function writeInt16BE(value, offset, noAssert) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000);
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    this[offset] = value >>> 8;
    this[offset + 1] = value & 0xff;
  } else {
    objectWriteUInt16(this, value, offset, false);
  }
  return offset + 2;
};

Buffer.prototype.writeInt32LE = function writeInt32LE(value, offset, noAssert) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000);
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    this[offset] = value & 0xff;
    this[offset + 1] = value >>> 8;
    this[offset + 2] = value >>> 16;
    this[offset + 3] = value >>> 24;
  } else {
    objectWriteUInt32(this, value, offset, true);
  }
  return offset + 4;
};

Buffer.prototype.writeInt32BE = function writeInt32BE(value, offset, noAssert) {
  value = +value;
  offset = offset | 0;
  if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000);
  if (value < 0) value = 0xffffffff + value + 1;
  if (Buffer.TYPED_ARRAY_SUPPORT) {
    this[offset] = value >>> 24;
    this[offset + 1] = value >>> 16;
    this[offset + 2] = value >>> 8;
    this[offset + 3] = value & 0xff;
  } else {
    objectWriteUInt32(this, value, offset, false);
  }
  return offset + 4;
};

function checkIEEE754(buf, value, offset, ext, max, min) {
  if (offset + ext > buf.length) throw new RangeError('Index out of range');
  if (offset < 0) throw new RangeError('Index out of range');
}

function writeFloat(buf, value, offset, littleEndian, noAssert) {
  if (!noAssert) {
    checkIEEE754(buf, value, offset, 4);
  }
  write(buf, value, offset, littleEndian, 23, 4);
  return offset + 4;
}

Buffer.prototype.writeFloatLE = function writeFloatLE(value, offset, noAssert) {
  return writeFloat(this, value, offset, true, noAssert);
};

Buffer.prototype.writeFloatBE = function writeFloatBE(value, offset, noAssert) {
  return writeFloat(this, value, offset, false, noAssert);
};

function writeDouble(buf, value, offset, littleEndian, noAssert) {
  if (!noAssert) {
    checkIEEE754(buf, value, offset, 8);
  }
  write(buf, value, offset, littleEndian, 52, 8);
  return offset + 8;
}

Buffer.prototype.writeDoubleLE = function writeDoubleLE(
  value,
  offset,
  noAssert
) {
  return writeDouble(this, value, offset, true, noAssert);
};

Buffer.prototype.writeDoubleBE = function writeDoubleBE(
  value,
  offset,
  noAssert
) {
  return writeDouble(this, value, offset, false, noAssert);
};

// copy(targetBuffer, targetStart=0, sourceStart=0, sourceEnd=buffer.length)
Buffer.prototype.copy = function copy(target, targetStart, start, end) {
  if (!start) start = 0;
  if (!end && end !== 0) end = this.length;
  if (targetStart >= target.length) targetStart = target.length;
  if (!targetStart) targetStart = 0;
  if (end > 0 && end < start) end = start;

  // Copy 0 bytes; we're done
  if (end === start) return 0;
  if (target.length === 0 || this.length === 0) return 0;

  // Fatal error conditions
  if (targetStart < 0) {
    throw new RangeError('targetStart out of bounds');
  }
  if (start < 0 || start >= this.length)
    throw new RangeError('sourceStart out of bounds');
  if (end < 0) throw new RangeError('sourceEnd out of bounds');

  // Are we oob?
  if (end > this.length) end = this.length;
  if (target.length - targetStart < end - start) {
    end = target.length - targetStart + start;
  }

  var len = end - start;
  var i;

  if (this === target && start < targetStart && targetStart < end) {
    // descending copy from end
    for (i = len - 1; i >= 0; --i) {
      target[i + targetStart] = this[i + start];
    }
  } else if (len < 1000 || !Buffer.TYPED_ARRAY_SUPPORT) {
    // ascending copy from start
    for (i = 0; i < len; ++i) {
      target[i + targetStart] = this[i + start];
    }
  } else {
    Uint8Array.prototype.set.call(
      target,
      this.subarray(start, start + len),
      targetStart
    );
  }

  return len;
};

// Usage:
//    buffer.fill(number[, offset[, end]])
//    buffer.fill(buffer[, offset[, end]])
//    buffer.fill(string[, offset[, end]][, encoding])
Buffer.prototype.fill = function fill(val, start, end, encoding) {
  // Handle string cases:
  if (typeof val === 'string') {
    if (typeof start === 'string') {
      encoding = start;
      start = 0;
      end = this.length;
    } else if (typeof end === 'string') {
      encoding = end;
      end = this.length;
    }
    if (val.length === 1) {
      var code = val.charCodeAt(0);
      if (code < 256) {
        val = code;
      }
    }
    if (encoding !== undefined && typeof encoding !== 'string') {
      throw new TypeError('encoding must be a string');
    }
    if (typeof encoding === 'string' && !Buffer.isEncoding(encoding)) {
      throw new TypeError('Unknown encoding: ' + encoding);
    }
  } else if (typeof val === 'number') {
    val = val & 255;
  }

  // Invalid ranges are not set to a default, so can range check early.
  if (start < 0 || this.length < start || this.length < end) {
    throw new RangeError('Out of range index');
  }

  if (end <= start) {
    return this;
  }

  start = start >>> 0;
  end = end === undefined ? this.length : end >>> 0;

  if (!val) val = 0;

  var i;
  if (typeof val === 'number') {
    for (i = start; i < end; ++i) {
      this[i] = val;
    }
  } else {
    var bytes = internalIsBuffer(val)
      ? val
      : utf8ToBytes(new Buffer(val, encoding).toString());
    var len = bytes.length;
    for (i = 0; i < end - start; ++i) {
      this[i + start] = bytes[i % len];
    }
  }

  return this;
};

// HELPER FUNCTIONS
// ================

var INVALID_BASE64_RE = /[^+\/0-9A-Za-z-_]/g;

function base64clean(str) {
  // Node strips out invalid characters like \n and \t from the string, base64-js does not
  str = stringtrim(str).replace(INVALID_BASE64_RE, '');
  // Node converts strings with length < 2 to ''
  if (str.length < 2) return '';
  // Node allows for non-padded base64 strings (missing trailing ===), base64-js does not
  while (str.length % 4 !== 0) {
    str = str + '=';
  }
  return str;
}

function stringtrim(str) {
  if (str.trim) return str.trim();
  return str.replace(/^\s+|\s+$/g, '');
}

function toHex(n) {
  if (n < 16) return '0' + n.toString(16);
  return n.toString(16);
}

function utf8ToBytes(string, units) {
  units = units || Infinity;
  var codePoint;
  var length = string.length;
  var leadSurrogate = null;
  var bytes = [];

  for (var i = 0; i < length; ++i) {
    codePoint = string.charCodeAt(i);

    // is surrogate component
    if (codePoint > 0xd7ff && codePoint < 0xe000) {
      // last char was a lead
      if (!leadSurrogate) {
        // no lead yet
        if (codePoint > 0xdbff) {
          // unexpected trail
          if ((units -= 3) > -1) bytes.push(0xef, 0xbf, 0xbd);
          continue;
        } else if (i + 1 === length) {
          // unpaired lead
          if ((units -= 3) > -1) bytes.push(0xef, 0xbf, 0xbd);
          continue;
        }

        // valid lead
        leadSurrogate = codePoint;

        continue;
      }

      // 2 leads in a row
      if (codePoint < 0xdc00) {
        if ((units -= 3) > -1) bytes.push(0xef, 0xbf, 0xbd);
        leadSurrogate = codePoint;
        continue;
      }

      // valid surrogate pair
      codePoint =
        (((leadSurrogate - 0xd800) << 10) | (codePoint - 0xdc00)) + 0x10000;
    } else if (leadSurrogate) {
      // valid bmp char, but last char was a lead
      if ((units -= 3) > -1) bytes.push(0xef, 0xbf, 0xbd);
    }

    leadSurrogate = null;

    // encode utf8
    if (codePoint < 0x80) {
      if ((units -= 1) < 0) break;
      bytes.push(codePoint);
    } else if (codePoint < 0x800) {
      if ((units -= 2) < 0) break;
      bytes.push((codePoint >> 0x6) | 0xc0, (codePoint & 0x3f) | 0x80);
    } else if (codePoint < 0x10000) {
      if ((units -= 3) < 0) break;
      bytes.push(
        (codePoint >> 0xc) | 0xe0,
        ((codePoint >> 0x6) & 0x3f) | 0x80,
        (codePoint & 0x3f) | 0x80
      );
    } else if (codePoint < 0x110000) {
      if ((units -= 4) < 0) break;
      bytes.push(
        (codePoint >> 0x12) | 0xf0,
        ((codePoint >> 0xc) & 0x3f) | 0x80,
        ((codePoint >> 0x6) & 0x3f) | 0x80,
        (codePoint & 0x3f) | 0x80
      );
    } else {
      throw new Error('Invalid code point');
    }
  }

  return bytes;
}

function asciiToBytes(str) {
  var byteArray = [];
  for (var i = 0; i < str.length; ++i) {
    // Node's code seems to be doing this and not & 0x7F..
    byteArray.push(str.charCodeAt(i) & 0xff);
  }
  return byteArray;
}

function utf16leToBytes(str, units) {
  var c, hi, lo;
  var byteArray = [];
  for (var i = 0; i < str.length; ++i) {
    if ((units -= 2) < 0) break;

    c = str.charCodeAt(i);
    hi = c >> 8;
    lo = c % 256;
    byteArray.push(lo);
    byteArray.push(hi);
  }

  return byteArray;
}

function base64ToBytes(str) {
  return toByteArray(base64clean(str));
}

function blitBuffer(src, dst, offset, length) {
  for (var i = 0; i < length; ++i) {
    if (i + offset >= dst.length || i >= src.length) break;
    dst[i + offset] = src[i];
  }
  return i;
}

function isnan(val) {
  return val !== val; // eslint-disable-line no-self-compare
}

// the following is from is-buffer, also by Feross Aboukhadijeh and with same lisence
// The _isBuffer check is for Safari 5-7 support, because it's missing
// Object.prototype.constructor. Remove this eventually
export function isBuffer(obj) {
  return (
    obj != null && (!!obj._isBuffer || isFastBuffer(obj) || isSlowBuffer(obj))
  );
}

function isFastBuffer(obj) {
  return (
    !!obj.constructor &&
    typeof obj.constructor.isBuffer === 'function' &&
    obj.constructor.isBuffer(obj)
  );
}

// For Node v0.10 support. Remove this eventually.
function isSlowBuffer(obj) {
  return (
    typeof obj.readFloatLE === 'function' &&
    typeof obj.slice === 'function' &&
    isFastBuffer(obj.slice(0, 0))
  );
}