




 
The generic function 
stream-read-buffer
 is called by stream-fill-buffer to place characters into the region of the buffer 
buffer
 bounded by 
start
 and 
end
.
stream should be an instance of a subclass of buffered-stream.
stream-read-buffer
 should block until some data is available. 
result
 should be the number of characters actually placed in the buffer (0 if at end of file). This method must be implemented for subclasses of buffered-stream that handle input.