 it can process, and writes as many as
<tt>avail_out</tt> bytes to <tt>next_out</tt>.  Those counters and pointers are then
updated past the input data consumed and the output data written.  It is the amount of
output space available that may limit how much input is consumed.
Hence the inner loop to make sure that
all of the input is consumed by providing more output space each time.  Since <tt>avail_in</tt>
and <tt>next_in</tt> are updated by <tt>deflate()</tt>, we don't have to mess with those
between <tt