static long longFromBytes_littleEndian_partial(byte[] a, int i) {
  ret (ubyteToLong(i+7 >= a.length ? 0 : a[i+7]) << 56
    | (ubyteToLong(i+6 >= a.length ? 0 : a[i+6]) << 48
    | (ubyteToLong(i+5 >= a.length ? 0 : a[i+5]) << 40
    | (ubyteToLong(i+4 >= a.length ? 0 : a[i+4]) << 32
    | (ubyteToLong(i+3 >= a.length ? 0 : a[i+3]) << 24
    | (ubyteToLong(i+2 >= a.length ? 0 : a[i+2]) << 16
    | (ubyteToLong(i+1 >= a.length ? 0 : a[i+1]) << 8
    | ubyteToLong(a[i]);
}

Began life as a copy of #1031658