const _fromCharCode = String.fromCharCode
export function pack_base64(arr) {
  let res=''
  const u8 = new Uint8Array(arr.buffer || arr)
  const len = u8.byteLength
  for (let i=0; i<len; i++)
    res += _fromCharCode(u8[i])
  return window.btoa(res)
}

const _charCodeAt = ''.charCodeAt
export function unpack_base64(str_b64) {
  const sz = window.atob(str_b64)
  const len = sz.length
  const res = new Uint8Array(len)
  for (let i=0; i<len; i++)
    res[i] = _charCodeAt.call(sz, i)
  return res
}