An input stream.
A stream buffer.
Bounding indexes for a subsequence of buffer.
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.
LispWorks User Guide and Reference Manual - 20 Sep 2017