Function svn_txdelta_next_window 

pub unsafe extern "C" fn svn_txdelta_next_window(
    window: *mut *mut svn_txdelta_window_t,
    stream: *mut svn_txdelta_stream_t,
    pool: *mut apr_pool_t,
) -> *mut svn_error_t

Set @a *window to a pointer to the next window from the delta stream @a stream. When we have completely reconstructed the target string, set @a *window to zero.

The window will be allocated in @a pool.