/*
 * Returns number of bytes of free spaces in output buffer.  Because the free
 * space is allocated automatically, this method returns 0 normally.
 */
static VALUE
rb_zstream_avail_out(obj)
    VALUE obj;
{
    struct zstream *z;
    Data_Get_Struct(obj, struct zstream, z);
    return rb_uint2inum(z->stream.avail_out);
}