;;; -*- Package: Lisp -*-
;;;
;;; **********************************************************************
;;; This code was written as part of the CMU Common Lisp project at
;;; Carnegie Mellon University, and has been placed in the public domain.
;;;
(ext:file-comment
  "$Header: /project/cmucl/cvsroot/src/code/stream.lisp,v 1.81 2005/07/01 14:54:41 rtoy Exp $")
;;;
;;; **********************************************************************
;;;
;;; Stream functions for Spice Lisp.
;;; Written by Skef Wholey and Rob MacLachlan.
;;; Gray streams support by Douglas Crosher, 1998.
;;; Simple-streams support by Paul Foley, 2003.
;;;
;;; This file contains the OS-independent stream functions.
;;;
(in-package "LISP")

(export '(broadcast-stream make-broadcast-stream broadcast-stream-streams 
	  synonym-stream make-synonym-stream synonym-stream-symbol
	  concatenated-stream make-concatenated-stream
	  concatenated-stream-streams
	  two-way-stream make-two-way-stream two-way-stream-input-stream
	  two-way-stream-output-stream
	  echo-stream make-echo-stream echo-stream-input-stream
	  echo-stream-output-stream
	  make-string-input-stream make-string-output-stream
	  get-output-stream-string stream-element-type input-stream-p
	  output-stream-p open-stream-p interactive-stream-p
	  open-stream-p close read-line read-char
	  unread-char peek-char listen read-char-no-hang clear-input read-byte
	  write-char write-string write-line terpri fresh-line
	  finish-output force-output clear-output write-byte
          stream streamp string-stream
	  *standard-input* *standard-output*
          *error-output* *query-io* *debug-io* *terminal-io* *trace-output*))

(in-package "SYSTEM")
(export '(make-indenting-stream read-n-bytes))

(in-package "EXT")

(export '(get-stream-command
	  stream-command stream-command-p stream-command-name 
	  stream-command-args make-stream-command make-case-frob-stream))

(in-package "LISP")

;;;; Standard streams:
;;;
;;; The initialization of these streams is performed by Stream-Init,
;;; which lives in the file of machine-specific stream functions.
;;;
(defvar *terminal-io* () "Terminal I/O stream.")
(defvar *standard-input* () "Default input stream.")
(defvar *standard-output* () "Default output stream.")
(defvar *error-output* () "Error output stream.")
(defvar *query-io* () "Query I/O stream.")
(defvar *trace-output* () "Trace output stream.")
(defvar *debug-io* () "Interactive debugging stream.")

(defun ill-in-any (stream &rest ignore)
  (declare (ignore ignore))
  (error 'simple-type-error
	 :datum stream
	 :expected-type '(satisfies input-stream-p)
	 :format-control "~S is not an input stream."
	 :format-arguments (list stream)))
(defun ill-out-any (stream &rest ignore)
  (declare (ignore ignore))
  (error 'simple-type-error
	 :datum stream
	 :expected-type '(satisfies output-stream-p)
	 :format-control "~S is not an output stream."
	 :format-arguments (list stream)))
(defun ill-in (stream &rest ignore)
  (declare (ignore ignore))
  (error 'simple-type-error
	 :datum stream
	 :expected-type '(satisfies input-stream-p)
	 :format-control "~S is not a character input stream."
	 :format-arguments (list stream)))
(defun ill-out (stream &rest ignore)
  (declare (ignore ignore))
  (error 'simple-type-error
	 :datum stream
	 :expected-type '(satisfies output-stream-p)
	 :format-control "~S is not a character output stream."
	 :format-arguments (list stream)))
(defun ill-bin (stream &rest ignore)
  (declare (ignore ignore))
  (error 'simple-type-error
	 :datum stream
	 :expected-type '(satisfies input-stream-p)
	 :format-control "~S is not a binary input stream."
	 :format-arguments (list stream)))
(defun ill-n-bin (stream &rest ignore)
  (declare (ignore ignore))
  (error 'simple-type-error
	 :datum stream
	 :expected-type '(satisfies input-stream-p)
	 :format-control "~S is not a binary input stream ~
                          or does not support multi-byte read operations."
	 :format-arguments (list stream)))
(defun ill-bout (stream &rest ignore)
  (declare (ignore ignore))
  (error 'simple-type-error
	 :datum stream
	 :expected-type '(satisfies output-stream-p)
	 :format-control "~S is not a binary output stream."
	 :format-arguments (list stream)))
(defun closed-flame (stream &rest ignore)
  (declare (ignore ignore))
  (error "~S is closed." stream))
(defun do-nothing (&rest ignore)
  (declare (ignore ignore)))
(defun no-gray-streams (stream)
  (error 'simple-type-error
	 :datum stream
	 :expected-type 'stream
	 :format-control "~S is an unsupported Gray stream."
	 :format-arguments (list stream)))

(defun %print-stream (structure stream d)
  (declare (ignore d structure))
  (write-string "#<Bare Stream>" stream))

;;; HOW THE STREAM STRUCTURE IS USED:
;;;
;;;    Many of the slots of the stream structure contain functions
;;; which are called to perform some operation on the stream.  Closed
;;; streams have #'Closed-Flame in all of their function slots.  If
;;; one side of an I/O or echo stream is closed, the whole stream is
;;; considered closed.  The functions in the operation slots take
;;; arguments as follows:
;;;
;;; In:			Stream, Eof-Errorp, Eof-Value
;;; Bin:		Stream, Eof-Errorp, Eof-Value
;;; N-Bin:		Stream, Buffer, Start, Numbytes, Eof-Errorp
;;; Out:		Stream, Character
;;; Bout:		Stream, Integer
;;; Sout:		Stream, String, Start, End
;;; Misc:		Stream, Operation, &Optional Arg1, Arg2
;;;
;;;    In order to save space, some of the less common stream operations
;;; are handled by just one function, the Misc method.  This function
;;; is passed a keyword which indicates the operation to perform.
;;; The following keywords are used:
;;;
;;;  :listen 		- Return the following values:
;;; 			     t if any input waiting.
;;; 			     :eof if at eof.
;;; 			     nil if no input is available and not at eof.
;;;  :unread		- Unread the character Arg.
;;;  :close		- Do any stream specific stuff to close the stream.
;;;			  The methods are set to closed-flame by the close
;;;			  function, so that need not be done by this
;;;			  function.
;;;  :clear-input 	- Clear any unread input
;;;  :finish-output,
;;;  :force-output	- Cause output to happen
;;;  :clear-output	- Clear any undone output
;;;  :element-type 	- Return the type of element the stream deals with.
;;;  :line-length	- Return the length of a line of output.
;;;  :charpos		- Return current output position on the line.
;;;  :file-length	- Return the file length of a file stream.
;;;  :file-position	- Return or change the current position of a file stream.
;;;  :file-name		- Return the name of an associated file.
;;;  :interactive-p     - Is this an interactive device?
;;;
;;;    In order to do almost anything useful, it is necessary to
;;; define a new type of structure that includes stream, so that the
;;; stream can have some state information.
;;;
;;; THE STREAM IN-BUFFER:
;;;
;;;    The In-Buffer in the stream holds characters or bytes that
;;; are ready to be read by some input function.  If there is any
;;; stuff in the In-Buffer, then the reading function can use it
;;; without calling any stream method.  Any stream may put stuff in
;;; the In-Buffer, and may also assume that any input in the In-Buffer
;;; has been consumed before any in-method is called.  If a text
;;; stream has in In-Buffer, then the first character should not be
;;; used to buffer normal input so that it is free for unreading into.
;;;
;;;    The In-Buffer slot is a vector In-Buffer-Length long.  The
;;; In-Index is the index in the In-Buffer of the first available
;;; object.  The available objects are thus between In-Index and the
;;; length of the In-Buffer.
;;;
;;;    When this buffer is only accessed by the normal stream
;;; functions, the number of function calls is halved, thus
;;; potentially doubling the speed of simple operations.  If the
;;; Fast-Read-Char and Fast-Read-Byte macros are used, nearly all
;;; function call overhead is removed, vastly speeding up these
;;; important operations.
;;;
;;;    If a stream does not have an In-Buffer, then the In-Buffer slot
;;; must be nil, and the In-Index must be In-Buffer-Length.  These are
;;; the default values for the slots. 


;;; Stream manipulation functions.

(defun input-stream-p (stream)
  "Returns non-nil if the given Stream can perform input operations."
  (declare (type stream stream))
  ;; Note: Gray streams redefines this function; any changes made here need
  ;; to be duplicated in .../pcl/gray-streams.lisp
  (stream-dispatch stream
    ;; simple-stream
    (stream::%input-stream-p stream)
    ;; lisp-stream
    (let ((stream (if (synonym-stream-p stream)
		      (symbol-value (synonym-stream-symbol stream))
		      stream)))
      (and (not (eq (lisp-stream-in stream) #'closed-flame))
	   (or (not (eq (lisp-stream-in stream) #'ill-in))
	       (not (eq (lisp-stream-bin stream) #'ill-bin))
	       (not (eq (lisp-stream-n-bin stream) #'ill-n-bin)))))))

(defun output-stream-p (stream)
  "Returns non-nil if the given Stream can perform output operations."
  (declare (type stream stream))
  ;; Note: Gray streams redefines this function; any changes made here need
  ;; to be duplicated in .../pcl/gray-streams.lisp
  (stream-dispatch stream
    ;; simple-stream
    (stream::%output-stream-p stream)
    ;; lisp-stream
    (let ((stream (if (synonym-stream-p stream)
		      (symbol-value (synonym-stream-symbol stream))
		      stream)))
      (and (not (eq (lisp-stream-in stream) #'closed-flame))
	   (or (not (eq (lisp-stream-out stream) #'ill-out))
	       (not (eq (lisp-stream-bout stream) #'ill-bout)))))))

(defun open-stream-p (stream)
  "Return true if Stream is not closed."
  (declare (type stream stream))
  ;; Note: Gray streams redefines this function; any changes made here need
  ;; to be duplicated in .../pcl/gray-streams.lisp
  (stream-dispatch stream
    ;; simple-stream
    (stream::%open-stream-p stream)
    ;; lisp-stream
    (not (eq (lisp-stream-in stream) #'closed-flame))))

(defun stream-element-type (stream)
  "Returns a type specifier for the kind of object returned by the Stream."
  (declare (type stream stream))
  ;; Note: Gray streams redefines this function; any changes made here need
  ;; to be duplicated in .../pcl/gray-streams.lisp
  (stream-dispatch stream
    ;; simple-stream
    '(unsigned-byte 8)
    ;; lisp-stream
    (funcall (lisp-stream-misc stream) stream :element-type)))

(defun interactive-stream-p (stream)
  "Return true if Stream does I/O on a terminal or other interactive device."
  (declare (type stream stream))
  (stream-dispatch stream
    ;; simple-stream
    (stream::%interactive-stream-p stream)
    ;; lisp-stream
    (funcall (lisp-stream-misc stream) stream :interactive-p)))

(defun (setf interactive-stream-p) (flag stream)
  (declare (type stream stream))
  (stream-dispatch stream
    ;; simple-stream
    (if flag
	(stream::%interactive-stream-y stream)
	(stream::%interactive-stream-n stream))
    ;; lisp-stream
    (error 'simple-type-error
	   :datum stream
	   :expected-type 'stream:simple-stream
	   :format-control "Can't set interactive flag on ~S."
	   :format-arguments (list stream))))

(defun stream-external-format (stream)
  "Returns the external format used by the given Stream."
  (declare (type stream stream))
  (stream-dispatch stream
    ;; simple-stream
    (stream::%stream-external-format stream)
    ;; lisp-stream
    :default
    ;; fundamental-stream
    :default))

(defun close (stream &key abort)
  "Closes the given Stream.  No more I/O may be performed, but inquiries
  may still be made.  If :Abort is non-nil, an attempt is made to clean
  up the side effects of having created the stream."
  (declare (type stream stream))
  ;; Note: Gray streams redefines this function; any changes made here need
  ;; to be duplicated in .../pcl/gray-streams.lisp
  (stream-dispatch stream
    ;; simple-stream
    (stream:device-close stream abort)
    ;; lisp-stream
    (when (open-stream-p stream)
      (funcall (lisp-stream-misc stream) stream :close abort)))
  t)

(defun set-closed-flame (stream)
  (declare (type lisp-stream stream))
  (setf (lisp-stream-in stream) #'closed-flame)
  (setf (lisp-stream-bin stream) #'closed-flame)
  (setf (lisp-stream-n-bin stream) #'closed-flame)
  (setf (lisp-stream-in stream) #'closed-flame)
  (setf (lisp-stream-out stream) #'closed-flame)
  (setf (lisp-stream-bout stream) #'closed-flame)
  (setf (lisp-stream-sout stream) #'closed-flame)
  (setf (lisp-stream-misc stream) #'closed-flame))


;;;; File position and file length.

;;; File-Position  --  Public
;;;
;;;    Call the misc method with the :file-position operation.
;;;
(defun file-position (stream &optional position)
  "With one argument returns the current position within the file
   File-Stream is open to.  If the second argument is supplied, then
   this becomes the new file position.  The second argument may also
   be :start or :end for the start and end of the file, respectively."
  (declare (type stream stream)
	   (type (or (integer 0 *) (member nil :start :end)) position))
  (stream-dispatch stream
    ;; simple-stream
    (stream::%file-position stream position)
    ;; lisp-stream
    (cond
      (position
       (setf (lisp-stream-in-index stream) in-buffer-length)
       (funcall (lisp-stream-misc stream) stream :file-position position))
      (t
       (let ((res (funcall (lisp-stream-misc stream) stream
			   :file-position nil)))
	 (when res
	   (- res (- in-buffer-length (lisp-stream-in-index stream)))))))))


;;; File-Length  --  Public
;;;
;;;    Like File-Position, only use :file-length.
;;;
(defun file-length (stream)
  "This function returns the length of the file that File-Stream is open to."
  (stream-dispatch stream
    ;; simple-stream
    (stream::%file-length stream)
    ;; lisp-stream
    (funcall (lisp-stream-misc stream) stream :file-length)))


;;; Input functions:

(defun read-line (&optional (stream *standard-input*) (eof-errorp t) eof-value
			    recursive-p)
  "Returns a line of text read from the Stream as a string, discarding the
  newline character."
  (let ((stream (in-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%read-line stream eof-errorp eof-value recursive-p)
      ;; lisp-stream
      (prepare-for-fast-read-char stream
        (let ((res (make-string 80))
	      (len 80)
	      (index 0))
	  (loop
	    (let ((ch (fast-read-char nil nil)))
	      (cond (ch
		     (when (char= ch #\newline)
		       (done-with-fast-read-char)
		       (return (values (shrink-vector res index) nil)))
		     (when (= index len)
		       (setq len (* len 2))
		       (let ((new (make-string len)))
			 (replace new res)
			 (setq res new)))
		     (setf (schar res index) ch)
		     (incf index))
		    ((zerop index)
		     (done-with-fast-read-char)
		     (return (values (eof-or-lose stream eof-errorp eof-value)
				     t)))
		    ;; since fast-read-char hit already the eof char, we
		    ;; shouldn't do another read-char
		    (t
		     (done-with-fast-read-char)
		     (return (values (shrink-vector res index) t))))))))
      ;; fundamental-stream
      (multiple-value-bind (string eof)
	  (stream-read-line stream)
	(if (and eof (zerop (length string)))
	    (values (eof-or-lose stream eof-errorp eof-value) t)
	    (values string eof))))))

;;; We proclaim them inline here, then proclaim them notinline at EOF,
;;; so, except in this file, they are not inline by default, but they can be.
;;;
(declaim (inline read-char unread-char read-byte listen))
(defun read-char (&optional (stream *standard-input*) (eof-errorp t) eof-value
			    recursive-p)
  "Inputs a character from Stream and returns it."
  (let ((stream (in-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%read-char stream eof-errorp eof-value recursive-p t)
      ;; lisp-stream
      (prepare-for-fast-read-char stream
	(prog1
	    (fast-read-char eof-errorp eof-value)
	  (done-with-fast-read-char)))
      ;; fundamental-stream
      (let ((char (stream-read-char stream)))
	(if (eq char :eof)
	    (eof-or-lose stream eof-errorp eof-value)
	    char)))))

(defun unread-char (character &optional (stream *standard-input*))
  "Puts the Character back on the front of the input Stream."
  (let ((stream (in-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%unread-char stream character)
      ;; lisp-stream
      (let ((index (1- (lisp-stream-in-index stream)))
	    (buffer (lisp-stream-in-buffer stream)))
	(declare (fixnum index))
	(when (minusp index) (error "Nothing to unread."))
	(cond (buffer
	       (setf (aref buffer index) (char-code character))
	       (setf (lisp-stream-in-index stream) index))
	      (t
	       (funcall (lisp-stream-misc stream) stream 
			:unread character))))
      ;; fundamental-stream
      (stream-unread-char stream character)))
  nil)

;;; In the interest of ``once and only once'' this macro contains the
;;; framework necessary to implement a peek-char function, which has
;;; two special-cases (one for gray streams and one for echo streams)
;;; in addition to the normal case.
;;;
;;; All arguments are forms which will be used for a specific purpose
;;; PEEK-TYPE - the current peek-type as defined by ANSI CL
;;; EOF-VALUE - the eof-value argument to peek-char
;;; CHAR-VAR - the variable which will be used to store the current character
;;; READ-FORM - the form which will be used to read a character
;;; READ-EOF - the result returned from READ-FORM when eof is reached.
;;; UNREAD-FORM - ditto for unread-char
;;; SKIPPED-CHAR-FORM - the form to execute when skipping a character
;;; EOF-DETECTED-FORM - the form to execute when EOF has been detected
;;;                     (this will default to CHAR-VAR)
(defmacro generalized-peeking-mechanism (peek-type eof-value char-var
					 read-form read-eof unread-form
					 &optional (skipped-char-form nil)
						   (eof-detected-form nil))
  `(let ((,char-var ,read-form))
    (cond ((eql ,char-var ,read-eof) 
	   ,(if eof-detected-form
		eof-detected-form
		eof-value))
	  ((characterp ,peek-type)
	   (do ((,char-var ,char-var ,read-form))
	       ((or (eql ,char-var ,read-eof) 
		    (char= ,char-var ,peek-type))
		(cond ((eql ,char-var ,read-eof)
		       ,(if eof-detected-form
			    eof-detected-form
			    eof-value))
		      (t ,unread-form
			 ,char-var)))
	     ,skipped-char-form))
	  ((eql ,peek-type t)
	   (do ((,char-var ,char-var ,read-form))
	       ((or (eql ,char-var ,read-eof)
		    (not (eql (get-cat-entry ,char-var *readtable*) whitespace)))
		(cond ((eql ,char-var ,read-eof)
		       ,(if eof-detected-form
			    eof-detected-form
			    eof-value))
		      (t ,unread-form
			 ,char-var)))
	     ,skipped-char-form))
	  ((null ,peek-type)
	   ,unread-form
	   ,(if eof-detected-form
		(when (eql char-var read-eof)
		  eof-detected-form))
	   ,char-var)
	  (t
	   (error "Impossible case reached in PEEK-CHAR")))))

(defun peek-char (&optional (peek-type nil) (stream *standard-input*)
			    (eof-errorp t) eof-value recursive-p)
  "Peeks at the next character in the input Stream.  See manual for details."
  ;; FIXME: The type of PEEK-TYPE is also declared in a DEFKNOWN, but
  ;; the compiler doesn't seem to be smart enough to go from there to
  ;; imposing a type check. Figure out why (because PEEK-TYPE is an
  ;; &OPTIONAL argument?) and fix it, and then this explicit type
  ;; check can go away.
  (unless (typep peek-type '(or character boolean))
    (error 'simple-type-error
	   :datum peek-type
	   :expected-type '(or character boolean)
	   :format-control "~@<bad PEEK-TYPE=~S, ~_expected ~S~:>"
	   :format-arguments (list peek-type '(or character boolean))))
  (let ((stream (in-synonym-of stream)))
    (if (typep stream 'echo-stream)
	(echo-misc stream :peek-char peek-type (list eof-errorp eof-value))
	(stream-dispatch stream
	  ;; simple-stream
	  (stream::%peek-char stream peek-type eof-errorp eof-value
			      recursive-p)
	  ;; lisp-stream
	  (generalized-peeking-mechanism
	   peek-type eof-value char
	   (read-char stream eof-errorp :eof)
	   :eof
	   (unread-char char stream)
	   nil
	   (eof-or-lose stream (or eof-errorp recursive-p) eof-value))
	  ;; fundamental-stream
	  (generalized-peeking-mechanism
	   peek-type :eof char
	   (if (null peek-type)
	       (stream-peek-char stream)
	       (stream-read-char stream))
	   (if (null peek-type)
	       ()
	       (stream-unread-char stream char))
	   ()
	   (eof-or-lose stream eof-errorp eof-value))))))

(defun listen (&optional (stream *standard-input*) (width 1))
  "Returns T if a character is available on the given Stream."
  (declare (type streamlike stream))
  (let ((stream (in-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%listen stream width)
      ;; lisp-stream
      (or (/= (the fixnum (lisp-stream-in-index stream)) in-buffer-length)
	  ;; Test for t explicitly since misc methods return :eof sometimes.
	  (eq (funcall (lisp-stream-misc stream) stream :listen) t))
      ;; fundamental-stream
      (stream-listen stream))))

(defun read-char-no-hang (&optional (stream *standard-input*)
				    (eof-errorp t) eof-value recursive-p)
  "Returns the next character from the Stream if one is available, or nil."
  (let ((stream (in-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%read-char stream eof-errorp eof-value recursive-p nil)
      ;; lisp-stream
      (if (funcall (lisp-stream-misc stream) stream :listen)
	  ;; On t or :eof get READ-CHAR to do the work.
	  (read-char stream eof-errorp eof-value)
	  nil)
      ;; fundamental-stream
      (let ((char (stream-read-char-no-hang stream)))
	(if (eq char :eof)
	    (eof-or-lose stream eof-errorp eof-value)
	    char)))))


(defun clear-input (&optional (stream *standard-input*) buffer-only)
  "Clears any buffered input associated with the Stream."
  (declare (type streamlike stream))
  (let ((stream (in-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%clear-input stream buffer-only)
      ;; lisp-stream
      (progn
	(setf (lisp-stream-in-index stream) in-buffer-length)
	(funcall (lisp-stream-misc stream) stream :clear-input))
      ;; fundamental-stream
      (stream-clear-input stream)))
  nil)

(defun read-byte (stream &optional (eof-errorp t) eof-value)
  "Returns the next byte of the Stream."
  (declare (type stream stream))
  (let ((stream (in-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%read-byte stream eof-errorp eof-value)
      ;; lisp-stream
      (prepare-for-fast-read-byte stream
	(prog1
	    (fast-read-byte eof-errorp eof-value t)
	  (done-with-fast-read-byte)))
      ;; fundamental-stream
      (let ((char (stream-read-byte stream)))
	(if (eq char :eof)
	    (eof-or-lose stream eof-errorp eof-value)
	    char)))))

(defun read-n-bytes (stream buffer start numbytes &optional (eof-errorp t))
  "Reads Numbytes bytes into the Buffer starting at Start, returning the number
   of bytes read.
   -- If EOF-ERROR-P is true, an END-OF-FILE condition is signalled if
      end-of-file is encountered before Count bytes have been read.
   -- If EOF-ERROR-P is false, READ-N-BYTES reads as much data as is currently
      available (up to count bytes).  On pipes or similar devices, this
      function returns as soon as any data is available, even if the amount
      read is less than Count and eof has not been hit."
  (declare (type lisp-stream stream)
	   (type index numbytes start)
	   (type (or (simple-array * (*)) system-area-pointer) buffer))
  (let* ((stream (in-synonym-of stream lisp-stream))
	 (in-buffer (lisp-stream-in-buffer stream))
	 (index (lisp-stream-in-index stream))
	 (num-buffered (- in-buffer-length index)))
    (declare (fixnum index num-buffered))
    (cond
     ((not in-buffer)
      (funcall (lisp-stream-n-bin stream) stream
	       buffer start numbytes eof-errorp))
     ((<= numbytes num-buffered)
      (%primitive byte-blt in-buffer index buffer start (+ start numbytes))
      (setf (lisp-stream-in-index stream) (+ index numbytes))
      numbytes)
     (t
      (let ((end (+ start num-buffered)))
	(%primitive byte-blt in-buffer index buffer start end)
	(setf (lisp-stream-in-index stream) in-buffer-length)
	(+ (funcall (lisp-stream-n-bin stream) stream buffer end
		    (- numbytes num-buffered)
		    eof-errorp)
	   num-buffered))))))


;;; Amount of space we leave at the start of the in-buffer for unreading.  4
;;; instead of 1 to allow word-aligned copies.
;;;
(defconstant in-buffer-extra 4)

;;; FAST-READ-CHAR-REFILL  --  Interface
;;;
;;;    This function is called by the fast-read-char expansion to refill the
;;; in-buffer for text streams.  There is definitely an in-buffer, and hence
;;; myst be an n-bin method.
;;;
(defun fast-read-char-refill (stream eof-errorp eof-value)
  (let* ((ibuf (lisp-stream-in-buffer stream))
	 (count (funcall (lisp-stream-n-bin stream) stream
			 ibuf in-buffer-extra
			 (- in-buffer-length in-buffer-extra)
			 nil))
	 (start (- in-buffer-length count)))
    (declare (type index start count))
    (cond ((zerop count)
	   (setf (lisp-stream-in-index stream) in-buffer-length)
	   (funcall (lisp-stream-in stream) stream eof-errorp eof-value))
	  (t
	   (when (/= start in-buffer-extra)
	     (bit-bash-copy ibuf (+ (* in-buffer-extra vm:byte-bits)
				    (* vm:vector-data-offset vm:word-bits))
			    ibuf (+ (the index (* start vm:byte-bits))
				    (* vm:vector-data-offset vm:word-bits))
			    (* count vm:byte-bits)))
	   (setf (lisp-stream-in-index stream) (1+ start))
	   (code-char (aref ibuf start))))))


;;; FAST-READ-BYTE-REFILL  --  Interface
;;;
;;;    Similar to FAST-READ-CHAR-REFILL, but we don't have to leave room for
;;; unreading.
;;;
(defun fast-read-byte-refill (stream eof-errorp eof-value)
  (let* ((ibuf (lisp-stream-in-buffer stream))
	 (count (funcall (lisp-stream-n-bin stream) stream
			 ibuf 0 in-buffer-length
			 nil))
	 (start (- in-buffer-length count)))
    (declare (type index start count))
    (cond ((zerop count)
	   (setf (lisp-stream-in-index stream) in-buffer-length)
	   (funcall (lisp-stream-bin stream) stream eof-errorp eof-value))
	  (t
	   (unless (zerop start)
	     (bit-bash-copy ibuf (* vm:vector-data-offset vm:word-bits)
			    ibuf (+ (the index (* start vm:byte-bits))
				    (* vm:vector-data-offset vm:word-bits))
			    (* count vm:byte-bits)))
	   (setf (lisp-stream-in-index stream) (1+ start))
	   (aref ibuf start)))))
  

;;; Output functions:

(defun write-char (character &optional (stream *standard-output*))
  "Outputs the Character to the Stream."
  (declare (type streamlike stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%write-char stream character)
      ;; lisp-stream
      (funcall (lisp-stream-out stream) stream character)
      ;; fundamental-stream
      (stream-write-char stream character)))
  character)

(defun terpri (&optional (stream *standard-output*))
  "Outputs a new line to the Stream."
  (declare (type streamlike stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%write-char stream #\Newline)
      ;; lisp-stream
      (funcall (lisp-stream-out stream) stream #\Newline)
      ;; fundamental-stream
      (stream-terpri stream)))
  nil)

(defun fresh-line (&optional (stream *standard-output*))
  "Outputs a new line to the Stream if it is not positioned at the beginning of
   a line.  Returns T if it output a new line, nil otherwise."
  (declare (type streamlike stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%fresh-line stream)
      ;; lisp-stream
      (when (/= (or (charpos stream) 1) 0)
	(funcall (lisp-stream-out stream) stream #\newline)
	t)
      ;; fundamental-stream
      (stream-fresh-line stream))))

(defun write-string (string &optional (stream *standard-output*)
			    &key (start 0) end)
  "Outputs the String to the given Stream."
  (write-string* string stream start (or end (length (the vector string)))))

(defun write-string* (string &optional (stream *standard-output*)
			     (start 0) (end (length (the vector string))))
  (declare (type streamlike stream) (fixnum start end))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (if (array-header-p string)
	  (with-array-data ((data string) (offset-start start)
			    (offset-end end))
	    (stream::%write-string stream data offset-start offset-end))
	  (stream::%write-string stream string start end))
      ;; lisp-stream
      (if (array-header-p string)
	  (with-array-data ((data string) (offset-start start)
			    (offset-end end))
	    (funcall (lisp-stream-sout stream)
		     stream data offset-start offset-end))
	  (funcall (lisp-stream-sout stream) stream string start end))
      ;; fundamental-stream
      (stream-write-string stream string start end)))
  string)

(defun write-line (string &optional (stream *standard-output*)
			  &key (start 0) (end (length string)))
  "Outputs the String to the given Stream, followed by a newline character."
  (write-line* string stream start (or end (length string))))

(defun write-line* (string &optional (stream *standard-output*)
			   (start 0) (end (length string)))
  (declare (type streamlike stream) (fixnum start end))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (progn
	(if (array-header-p string)
	    (with-array-data ((data string) (offset-start start)
			      (offset-end end))
	      (stream::%write-string stream data offset-start offset-end))
	    (stream::%write-string stream string start end))
	(stream::%write-char stream #\Newline))
      ;; lisp-stream
      (progn
	(if (array-header-p string)
	    (with-array-data ((data string) (offset-start start)
			      (offset-end end))
	      (funcall (lisp-stream-sout stream) stream data offset-start
							offset-end))
	    (funcall (lisp-stream-sout stream) stream string start end))
	(funcall (lisp-stream-out stream) stream #\newline))
      ;; fundamental-stream
      (progn
	(stream-write-string stream string start end)
	(stream-write-char stream #\Newline)))
    string))

(defun charpos (&optional (stream *standard-output*))
  "Returns the number of characters on the current line of output of the given
  Stream, or Nil if that information is not availible."
  (declare (type streamlike stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%charpos stream)
      ;; lisp-stream
      (funcall (lisp-stream-misc stream) stream :charpos)
      ;; fundamental-stream
      (stream-line-column stream))))

(defun line-length (&optional (stream *standard-output*))
  "Returns the number of characters that will fit on a line of output on the
  given Stream, or Nil if that information is not available."
  (declare (type streamlike stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%line-length stream)
      ;; lisp-stream
      (funcall (lisp-stream-misc stream) stream :line-length)
      ;; fundamental-stream
      (stream-line-length stream))))

(defun finish-output (&optional (stream *standard-output*))
  "Attempts to ensure that all output sent to the Stream has reached its
   destination, and only then returns."
  (declare (type streamlike stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%finish-output stream)
      ;; lisp-stream
      (funcall (lisp-stream-misc stream) stream :finish-output)
      ;; fundamental-stream
      (stream-finish-output stream)))
  nil)

(defun force-output (&optional (stream *standard-output*))
  "Attempts to force any buffered output to be sent."
  (declare (type streamlike stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%force-output stream)
      ;; lisp-stream-misc
      (funcall (lisp-stream-misc stream) stream :force-output)
      ;; fundamental-stream
      (stream-force-output stream)))
  nil)

(defun clear-output (&optional (stream *standard-output*))
  "Clears the given output Stream."
  (declare (type streamlike stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%clear-output stream)
      ;; lisp-stream
      (funcall (lisp-stream-misc stream) stream :clear-output)
      ;; fundamental-stream
      (stream-force-output stream)))
  nil)

(defun write-byte (integer stream)
  "Outputs the Integer to the binary Stream."
  (declare (type stream stream))
  (let ((stream (out-synonym-of stream)))
    (stream-dispatch stream
      ;; simple-stream
      (stream::%write-byte stream integer)
      ;; lisp-stream
      (funcall (lisp-stream-bout stream) stream integer)
      ;; fundamental-stream
      (stream-write-byte stream integer)))
  integer)


;;; Stream-misc-dispatch
;;;
;;; Called from lisp-stream routines that encapsulate CLOS streams to
;;; handle the misc routines and dispatch to the appropriate Gray
;;; stream functions.
;;;
(defun stream-misc-dispatch (stream operation &optional arg1 arg2)
  (declare (type fundamental-stream stream)
	   (ignore arg2))
  (case operation
    (:listen
     ;; Return true is input available, :eof for eof-of-file, otherwise Nil.
     (let ((char (stream-read-char-no-hang stream)))
       (when (characterp char)
	 (stream-unread-char stream char))
       char))
    (:unread
     (stream-unread-char stream arg1))
    (:close
     (close stream))
    (:clear-input
     (stream-clear-input stream))
    (:force-output
     (stream-force-output stream))
    (:finish-output
     (stream-finish-output stream))
    (:element-type
     (stream-element-type stream))
    (:interactive-p
     (interactive-stream-p stream))
    (:line-length
     (stream-line-length stream))
    (:charpos
     (stream-line-column stream))
    (:file-length
     (file-length stream))
    (:file-position
     (file-position stream arg1))))


;;;; Broadcast streams:

(defstruct (broadcast-stream (:include lisp-stream
				       (out #'broadcast-out)
				       (bout #'broadcast-bout)
				       (sout #'broadcast-sout)
				       (misc #'broadcast-misc))
			     (:print-function %print-broadcast-stream)
			     (:constructor %make-broadcast-stream (&rest streams)))
  ;; This is a list of all the streams we broadcast to.
  (streams () :type list :read-only t))

(defun make-broadcast-stream (&rest streams)
  "Returns an output stream which sends its output to all of the given
streams."
  (dolist (s streams)
    (unless (output-stream-p s)
      (ill-out-any s)))
  
  (apply #'%make-broadcast-stream streams))

(defun %print-broadcast-stream (s stream d)
  (declare (ignore s d))
  (write-string "#<Broadcast Stream>" stream))

(macrolet ((out-fun (fun method stream-method &rest args)
	     `(defun ,fun (stream ,@args)
		(dolist (stream (broadcast-stream-streams stream))
		  (stream-dispatch stream
		    ;; simple-stream
		    (,stream-method stream ,@args) ; use gray-compat for now
		    ;; lisp-stream
		    (funcall (,method stream) stream ,@args)
		    ;; fundamental-stream
		    (,stream-method stream ,@args))))))
  (out-fun broadcast-out lisp-stream-out stream-write-char char)
  (out-fun broadcast-bout lisp-stream-bout stream-write-byte byte)
  (out-fun broadcast-sout lisp-stream-sout stream-write-string
	   string start end))

(defun broadcast-misc (stream operation &optional arg1 arg2)
  (let ((streams (broadcast-stream-streams stream)))
    (case operation
      (:charpos
       (dolist (stream streams 0)
	 (let ((charpos (charpos stream)))
	   (if charpos (return charpos)))))
      (:line-length
       (let ((min nil))
	 (dolist (stream streams min)
	   (let ((res (line-length stream)))
	     (when res (setq min (if min (min res min) res)))))))
      ;; CLHS: The functions file-length, file-position, file-string-length, and
      ;; stream-external-format return the value from the last component
      ;; stream; if there are no component streams, file-length and
      ;; file-position return 0, file-string-length returns 1, and
      ;; stream-external-format returns :default.
      (:file-length
       (if (null streams) 0
           (file-length (first (last streams)))))
      (:file-position
       (if (null streams) 0
           (file-position (first (last streams)))))
      (:element-type
       #+nil ; old, arguably more logical, version
       (let (res)
	 (dolist (stream streams (if (> (length res) 1) `(and ,@res) t))
	   (pushnew (stream-element-type stream) res :test #'equal)))
       ;; ANSI-specified version (under System Class BROADCAST-STREAM)
       (let ((res t))
	 (do ((streams streams (cdr streams)))
	     ((null streams) res)
	   (when (null (cdr streams))
	     (setq res (stream-element-type (car streams)))))))
      (:close)
      (t
       (let ((res nil))
	 (dolist (stream streams res)
	   (setq res
		 (if (lisp-stream-p stream)
		     (funcall (lisp-stream-misc stream) stream operation
			      arg1 arg2)
		     (stream-misc-dispatch stream operation arg1 arg2)))))))))


;;;; Synonym Streams:

(defstruct (synonym-stream (:include lisp-stream
				     (in #'synonym-in)
				     (bin #'synonym-bin)
				     (n-bin #'synonym-n-bin)
				     (out #'synonym-out)
				     (bout #'synonym-bout)
				     (sout #'synonym-sout)
				     (misc #'synonym-misc))
			   (:print-function %print-synonym-stream)
			   (:constructor make-synonym-stream (symbol)))
  ;; This is the symbol, the value of which is the stream we are synonym to.
  (symbol nil :type symbol :read-only t))

(defun %print-synonym-stream (s stream d)
  (declare (ignore d))
  (format stream "#<Synonym Stream to ~S>" (synonym-stream-symbol s)))

(setf (documentation 'make-synonym-stream 'function)
  "Returns a stream which performs its operations on the stream which is the
   value of the dynamic variable named by Symbol.")

;;; The output simple output methods just call the corresponding method
;;; in the synonymed stream.
;;;
(macrolet ((out-fun (name slot stream-method &rest args)
	     `(defun ,name (stream ,@args)
		(declare (optimize (safety 1)))
		(let ((syn (symbol-value (synonym-stream-symbol stream))))
		  (if (lisp-stream-p syn)
		      (funcall (,slot syn) syn ,@args)
		      (,stream-method syn ,@args))))))
  (out-fun synonym-out lisp-stream-out stream-write-char ch)
  (out-fun synonym-bout lisp-stream-bout stream-write-byte n)
  (out-fun synonym-sout lisp-stream-sout stream-write-string string start end))


;;; Bind synonym stream to this so that SPIO can turn on the right frob in
;;; the icon when we are in a terminal input wait.
;;;
(defvar *previous-stream* nil)

;;; For the input methods, we just call the corresponding function on the
;;; synonymed stream.  These functions deal with getting input out of
;;; the In-Buffer if there is any.
;;;
(macrolet ((in-fun (name fun &rest args)
	     `(defun ,name (stream ,@args)
		(declare (optimize (safety 1)))
		(let ((*previous-stream* stream))
		  (,fun (symbol-value (synonym-stream-symbol stream)) ,@args)))))
  (in-fun synonym-in read-char eof-errorp eof-value)
  (in-fun synonym-bin read-byte eof-errorp eof-value)
  (in-fun synonym-n-bin read-n-bytes buffer start numbytes eof-errorp))


;;; Synonym-Misc  --  Internal
;;;
;;;    We have to special-case the operations which could look at stuff in
;;; the in-buffer.
;;;
(defun synonym-misc (stream operation &optional arg1 arg2)
  (declare (optimize (safety 1)))
  (let ((syn (symbol-value (synonym-stream-symbol stream)))
	(*previous-stream* stream))
    (if (lisp-stream-p syn)
	(case operation
	  (:listen (or (/= (the fixnum (lisp-stream-in-index syn))
			   in-buffer-length)
		       (funcall (lisp-stream-misc syn) syn :listen)))
	  (:clear-input (clear-input syn))
	  (:unread (unread-char arg1 syn))
	  (t
	   (funcall (lisp-stream-misc syn) syn operation arg1 arg2)))
	(stream-misc-dispatch syn operation arg1 arg2))))

;;;; Two-Way streams:

(defstruct (two-way-stream
	    (:include lisp-stream
		      (in #'two-way-in)
		      (bin #'two-way-bin)
		      (n-bin #'two-way-n-bin)
		      (out #'two-way-out)
		      (bout #'two-way-bout)
		      (sout #'two-way-sout)
		      (misc #'two-way-misc))
	    (:print-function %print-two-way-stream)
	    (:constructor %make-two-way-stream (input-stream output-stream)))
  ;; We read from this stream...
  (input-stream (required-argument) :type stream :read-only t)
  ;; And write to this one
  (output-stream (required-argument) :type stream :read-only t))

(defun %print-two-way-stream (s stream d)
  (declare (ignore d))
  (format stream "#<Two-Way Stream, Input = ~S, Output = ~S>"
	  (two-way-stream-input-stream s)
	  (two-way-stream-output-stream s)))

(defun make-two-way-stream (input-stream output-stream)
  "Returns a bidirectional stream which gets its input from Input-Stream and
   sends its output to Output-Stream."
  (unless (input-stream-p input-stream)
    (ill-in-any input-stream))
  (unless (output-stream-p output-stream)
    (ill-out-any output-stream))
  
  (%make-two-way-stream input-stream output-stream))

(macrolet ((out-fun (name slot stream-method &rest args)
	     `(defun ,name (stream ,@args)
		(let ((syn (two-way-stream-output-stream stream)))
		  (if (lisp-stream-p syn)
		      (funcall (,slot syn) syn ,@args)
		      (,stream-method syn ,@args))))))
  (out-fun two-way-out lisp-stream-out stream-write-char ch)
  (out-fun two-way-bout lisp-stream-bout stream-write-byte n)
  (out-fun two-way-sout lisp-stream-sout stream-write-string string start end))

(macrolet ((in-fun (name fun &rest args)
	     `(defun ,name (stream ,@args)
		(force-output (two-way-stream-output-stream stream))
		(,fun (two-way-stream-input-stream stream) ,@args))))
  (in-fun two-way-in read-char eof-errorp eof-value)
  (in-fun two-way-bin read-byte eof-errorp eof-value)
  (in-fun two-way-n-bin read-n-bytes buffer start numbytes eof-errorp))

(defun two-way-misc (stream operation &optional arg1 arg2)
  (let* ((in (two-way-stream-input-stream stream))
	 (out (two-way-stream-output-stream stream))
	 (in-lisp-stream-p (lisp-stream-p in))
	 (out-lisp-stream-p (lisp-stream-p out)))
    (case operation
      (:listen
       (if in-lisp-stream-p
	   (or (/= (the fixnum (lisp-stream-in-index in)) in-buffer-length)
	       (funcall (lisp-stream-misc in) in :listen))
	   (stream-listen in)))
      ((:finish-output :force-output :clear-output)
       (if out-lisp-stream-p
	   (funcall (lisp-stream-misc out) out operation arg1 arg2)
	   (stream-misc-dispatch out operation arg1 arg2)))
      (:clear-input (clear-input in))
      (:unread (unread-char arg1 in))
      (:element-type
       (let ((in-type (stream-element-type in))
	     (out-type (stream-element-type out)))
	 (if (equal in-type out-type)
	     in-type `(and ,in-type ,out-type))))
      (:close
       (set-closed-flame stream))
      (:file-length
       (error 'type-error :datum stream :expected-type 'file-stream))
      (:charpos
       (charpos out))
      (:line-length
       (line-length out))
      (t
       (or (if in-lisp-stream-p
	       (funcall (lisp-stream-misc in) in operation arg1 arg2)
	       (stream-misc-dispatch in operation arg1 arg2))
	   (if out-lisp-stream-p
	       (funcall (lisp-stream-misc out) out operation arg1 arg2)
	       (stream-misc-dispatch out operation arg1 arg2)))))))


;;;; Concatenated Streams:

(defstruct (concatenated-stream
	    (:include lisp-stream
		      (in #'concatenated-in)
		      (bin #'concatenated-bin)
		      (n-bin #'concatenated-n-bin)
		      (misc #'concatenated-misc))
	    (:print-function %print-concatenated-stream)
	    (:constructor %make-concatenated-stream (&rest streams)))
  ;; This is a list of all the streams. The car of this is the stream
  ;; we are reading from now.
  (streams nil :type list))

(defun %print-concatenated-stream (s stream d)
  (declare (ignore d))
  (format stream "#<Concatenated Stream, Streams = ~S>"
	  (concatenated-stream-streams s)))

(defun make-concatenated-stream (&rest streams)
  "Returns a stream which takes its input from each of the Streams in turn,
   going on to the next at EOF."
  (dolist (s streams)
    (unless (input-stream-p s)
      (ill-in-any s)))
  (apply #'%make-concatenated-stream streams))

(macrolet ((in-fun (name fun)
	     `(defun ,name (stream eof-errorp eof-value)
		(do ((current (concatenated-stream-streams stream)
			      (cdr current)))
		    ((null current)
		     (eof-or-lose stream eof-errorp eof-value))
		  (let* ((stream (car current))
			 (result (,fun stream nil nil)))
		    (when result (return result)))
		  (setf (concatenated-stream-streams stream) (cdr current))))))
  (in-fun concatenated-in read-char)
  (in-fun concatenated-bin read-byte))

(defun concatenated-n-bin (stream buffer start numbytes eof-errorp)
  (do ((current (concatenated-stream-streams stream) (cdr current))
       (current-start start)
       (remaining-bytes numbytes))
      ((null current)
       (if eof-errorp
	(error 'end-of-file :stream stream)
	(- numbytes remaining-bytes)))
    (let* ((stream (car current))
           (bytes-read (read-n-bytes stream buffer current-start
	                             remaining-bytes nil)))
      (incf current-start bytes-read)
      (decf remaining-bytes bytes-read)
      (when (zerop remaining-bytes) (return numbytes)))
    (setf (concatenated-stream-streams stream) (cdr current))))

(defun concatenated-misc (stream operation &optional arg1 arg2)
  (let ((current (first (concatenated-stream-streams stream))))
    (case operation
      (:listen
       (if current
           (loop
            (let ((stuff (if (lisp-stream-p current)
                             (funcall (lisp-stream-misc current) current
                                      :listen)
                             (stream-misc-dispatch current :listen))))
              (cond ((eq stuff :eof)
                     ;; Advance current, and try again.
                     (pop (concatenated-stream-streams stream))
                     (setf current (first (concatenated-stream-streams stream)))
                     (unless current (return :eof)))
                    (stuff
                     ;; Stuff's available.
                     (return t))
                    (t
                     ;; Nothing available yet.
                     (return nil)))))
           :eof))
      (:close
       (set-closed-flame stream))
      (:clear-input
       (when current (clear-input current)))
      (:unread
       (when current (unread-char arg1 current)))
      (:file-length
       (error 'type-error :datum stream :expected-type 'file-stream))
      (t
       (if (lisp-stream-p current)
           (funcall (lisp-stream-misc current) current operation arg1 arg2)
           (stream-misc-dispatch current operation arg1 arg2))))))


;;;; Echo Streams:

(defstruct (echo-stream
	    (:include two-way-stream
		      (in #'echo-in)
		      (bin #'echo-bin)
		      (misc #'echo-misc)
		      (n-bin #'echo-n-bin))
	    (:print-function %print-echo-stream)
	    (:constructor %make-echo-stream (input-stream output-stream)))
  unread-stuff)

(defun make-echo-stream (input-stream output-stream)
  "Returns an echo stream that takes input from Input-stream and sends
output to Output-stream"
  (unless (input-stream-p input-stream)
    (ill-in-any input-stream))
  (unless (output-stream-p output-stream)
    (ill-out-any output-stream))
  (%make-echo-stream input-stream output-stream))

(macrolet ((in-fun (name fun out-slot stream-method)
	     `(defun ,name (stream eof-errorp eof-value)
		(or (pop (echo-stream-unread-stuff stream))
		    (let* ((in (echo-stream-input-stream stream))
			   (out (echo-stream-output-stream stream))
			   (result (,fun in nil :eof)))
		      (cond ((eq result :eof)
			     (eof-or-lose stream eof-errorp eof-value))
			    (t
			     (if (lisp-stream-p out)
				 (funcall (,out-slot out) out result)
				 (,stream-method out result))
			     result)))))))
  (in-fun echo-in read-char lisp-stream-out stream-write-char)
  (in-fun echo-bin read-byte lisp-stream-bout stream-write-byte))


(defun echo-misc (stream operation &optional arg1 arg2)
  (let* ((in (two-way-stream-input-stream stream))
	 (out (two-way-stream-output-stream stream)))
    (case operation
      (:listen
       (or (not (null (echo-stream-unread-stuff stream)))
	   (if (lisp-stream-p in)
	       (or (/= (the fixnum (lisp-stream-in-index in)) in-buffer-length)
		   (funcall (lisp-stream-misc in) in :listen))
	       (stream-misc-dispatch in :listen))))
      (:unread (push arg1 (echo-stream-unread-stuff stream)))
      (:element-type
       (let ((in-type (stream-element-type in))
	     (out-type (stream-element-type out)))
	 (if (equal in-type out-type)
	     in-type `(and ,in-type ,out-type))))
      (:close
       (set-closed-flame stream))
      (:peek-char
       ;; For the special case of peeking into an echo-stream
       ;; arg1 is peek-type, arg2 is (eof-errorp eof-value)
       ;; returns peeked-char, eof-value, or errors end-of-file
       (let ((unread-char-p nil))
	 (destructuring-bind (eof-errorp eof-value)
	     arg2
	   (flet ((outfn (c)
		    (unless unread-char-p
		      (if (lisp-stream-p out)
			  (funcall (lisp-stream-out out) out c)
			  ;; gray-stream
			  (stream-write-char out c))))
		  (infn ()
		    ;; Obtain input from unread buffer or input stream,
		    ;; and set the flag appropriately.
		    (cond ((not (null (echo-stream-unread-stuff stream)))
			   (setf unread-char-p t)
			   (pop (echo-stream-unread-stuff stream)))
			  (t
			   (setf unread-char-p nil)
			   (read-char in eof-errorp :eof)))))
	     (generalized-peeking-mechanism
	      arg1 eof-value char
	      (infn)
	      :eof
	      (unread-char char in)
	      (outfn char))))))
      (:file-length
       (error 'type-error :datum stream :expected-type 'file-stream))
      (t
       (or (if (lisp-stream-p in)
	       (funcall (lisp-stream-misc in) in operation arg1 arg2)
	       (stream-misc-dispatch in operation arg1 arg2))
	   (if (lisp-stream-p out)
	       (funcall (lisp-stream-misc out) out operation arg1 arg2)
	       (stream-misc-dispatch out operation arg1 arg2)))))))


(defun echo-n-bin (stream buffer start numbytes eof-error-p)
  (let ((new-start start)
	(read 0))
    (loop
     (let ((thing (pop (echo-stream-unread-stuff stream))))
       (cond
	 (thing
	  (setf (aref buffer new-start) thing)
	  (incf new-start)
	  (incf read)
	  (when (= read numbytes)
	    (return-from echo-n-bin numbytes)))
	 (t (return nil)))))
    (let ((bytes-read (read-n-bytes (echo-stream-input-stream stream) buffer
				    new-start (- numbytes read) nil)))
      (cond
	((not eof-error-p)
	 (write-sequence buffer (echo-stream-output-stream stream)
			 :start new-start :end (+ new-start bytes-read))
	 (+ bytes-read read))
	((> numbytes (+ read bytes-read))
	 (write-sequence buffer (echo-stream-output-stream stream)
			 :start new-start :end (+ new-start bytes-read))
	 (error 'end-of-file :stream stream))
	(t
	 (write-sequence buffer (echo-stream-output-stream stream)
			 :start new-start :end (+ new-start bytes-read))
	 numbytes)))))

(defun %print-echo-stream (s stream d)
  (declare (ignore d))
  (format stream "#<Echo Stream, Input = ~S, Output = ~S>"
	  (two-way-stream-input-stream s)
	  (two-way-stream-output-stream s)))

(setf (documentation 'make-echo-stream 'function)
  "Returns a bidirectional stream which gets its input from Input-Stream and
   sends its output to Output-Stream.  In addition, all input is echoed to
   the output stream")

;;;; Superclass of all string streams

(defstruct (string-stream
	     (:include lisp-stream)
	     (:constructor nil)
	     (:copier nil)))

;;;; String Input Streams:

(defstruct (string-input-stream
	     (:include string-stream
		       (in #'string-inch)
		       (bin #'string-binch)
		       (n-bin #'string-stream-read-n-bytes)
		       (misc #'string-in-misc))
	     (:print-function %print-string-input-stream)
					;(:constructor nil)
	     (:constructor internal-make-string-input-stream
			   (string current end)))
  (string nil :type simple-string)
  (current nil :type index)
  (end nil :type index))

(defun %print-string-input-stream (s stream d)
  (declare (ignore s d))
  (write-string "#<String-Input Stream>" stream))
  
(defun string-inch (stream eof-errorp eof-value)
  (let ((string (string-input-stream-string stream))
	(index (string-input-stream-current stream)))
    (declare (simple-string string) (fixnum index))
    (cond ((= index (the index (string-input-stream-end stream)))
	   (eof-or-lose stream eof-errorp eof-value))
	  (t
	   (setf (string-input-stream-current stream) (1+ index))
	   (aref string index)))))

(defun string-binch (stream eof-errorp eof-value)
  (let ((string (string-input-stream-string stream))
	(index (string-input-stream-current stream)))
    (declare (simple-string string)
	     (type index index))
    (cond ((= index (the index (string-input-stream-end stream)))
	   (eof-or-lose stream eof-errorp eof-value))
	  (t
	   (setf (string-input-stream-current stream) (1+ index))
	   (char-code (aref string index))))))

(defun string-stream-read-n-bytes (stream buffer start requested eof-errorp)
  (declare (type string-input-stream stream)
	   (type index start requested))
  (let* ((string (string-input-stream-string stream))
	 (index (string-input-stream-current stream))
	 (available (- (string-input-stream-end stream) index))
	 (copy (min available requested)))
    (declare (simple-string string)
	     (type index index available copy))
    (when (plusp copy)
      (setf (string-input-stream-current stream)
	    (truly-the index (+ index copy)))
      (system:without-gcing
       (system-area-copy (vector-sap string)
			 (* index vm:byte-bits)
			 (if (typep buffer 'system-area-pointer)
			     buffer
			     (vector-sap buffer))
			 (* start vm:byte-bits)
			 (* copy vm:byte-bits))))
    (if (and (> requested copy) eof-errorp)
	(error 'end-of-file :stream stream)
	copy)))

(defun string-in-misc (stream operation &optional arg1 arg2)
  (declare (ignore arg2))
  (case operation
    (:file-position
     (if arg1
	 (setf (string-input-stream-current stream)
	       (case arg1
		 (:start 0)
		 (:end (length (string-input-stream-string stream)))
		 (t arg1)))
	 (string-input-stream-current stream)))
    (:file-length
     (error 'type-error :datum stream :expected-type 'file-stream))
    (:unread (decf (string-input-stream-current stream)))
    (:listen (or (/= (the fixnum (string-input-stream-current stream))
		     (the fixnum (string-input-stream-end stream)))
		 :eof))
    (:element-type 'base-char)))
  
(defun make-string-input-stream (string &optional
					(start 0) (end (length string)))
  "Returns an input stream which will supply the characters of String between
  Start and End in order."
  (declare (type string string)
	   (type index start)
	   (type (or index null) end))
  (internal-make-string-input-stream (coerce string 'simple-string)
				     start (or end (length string))))

;;;; String Output Streams:

(defstruct (string-output-stream
	    (:include string-stream
		      (out #'string-ouch)
		      (sout #'string-sout)
		      (misc #'string-out-misc))
	    (:print-function %print-string-output-stream)
	    (:constructor %make-string-output-stream ()))
  ;; The string we throw stuff in.
  (string (make-string 40) :type simple-string)
  ;; Index of the next location to use.
  (index 0 :type fixnum))

(defun %print-string-output-stream (s stream d)
  (declare (ignore s d))
  (write-string "#<String-Output Stream>" stream))

(defun make-string-output-stream (&key (element-type 'character))
  "Returns an Output stream which will accumulate all output given to it for
   the benefit of the function Get-Output-Stream-String."
  (declare (ignore element-type))
  (%make-string-output-stream))

(defun string-ouch (stream character)
  (let ((current (string-output-stream-index stream))
	(workspace (string-output-stream-string stream)))
    (declare (simple-string workspace) (fixnum current))
    (if (= current (the fixnum (length workspace)))
	(let ((new-workspace (make-string (* current 2))))
	  (replace new-workspace workspace)
	  (setf (aref new-workspace current) character)
	  (setf (string-output-stream-string stream) new-workspace))
	(setf (aref workspace current) character))
    (setf (string-output-stream-index stream) (1+ current))))

(defun string-sout (stream string start end)
  (declare (simple-string string) (fixnum start end))
  (let* ((current (string-output-stream-index stream))
	 (length (- end start))
	 (dst-end (+ length current))
	 (workspace (string-output-stream-string stream)))
    (declare (simple-string workspace)
	     (fixnum current length dst-end))
    (if (> dst-end (the fixnum (length workspace)))
	(let ((new-workspace (make-string (+ (* current 2) length))))
	  (replace new-workspace workspace :end2 current)
	  (replace new-workspace string
		   :start1 current :end1 dst-end
		   :start2 start :end2 end)
	  (setf (string-output-stream-string stream) new-workspace))
	(replace workspace string
		 :start1 current :end1 dst-end
		 :start2 start :end2 end))
    (setf (string-output-stream-index stream) dst-end)))

(defun string-out-misc (stream operation &optional arg1 arg2)
  (declare (ignore arg2))
  (case operation
    (:file-position
     (if (null arg1)
	 (string-output-stream-index stream)))
    (:file-length
     (error 'type-error :datum stream :expected-type 'file-stream))
    (:charpos
     (do ((index (1- (the fixnum (string-output-stream-index stream)))
		 (1- index))
	  (count 0 (1+ count))
	  (string (string-output-stream-string stream)))
	 ((< index 0) count)
       (declare (simple-string string)
		(fixnum index count))
       (if (char= (schar string index) #\newline)
	   (return count))))
    (:element-type 'base-char)
    (:close
     (set-closed-flame stream))))

(defun get-output-stream-string (stream)
  "Returns a string of all the characters sent to a stream made by
   Make-String-Output-Stream since the last call to this function."
  (declare (type string-output-stream stream))
  (let* ((length (string-output-stream-index stream))
	 (result (make-string length)))
    (replace result (string-output-stream-string stream))
    (setf (string-output-stream-index stream) 0)
    result))

(defun dump-output-stream-string (in-stream out-stream)
  "Dumps the characters buffer up in the In-Stream to the Out-Stream as
  Get-Output-Stream-String would return them."
  (write-string* (string-output-stream-string in-stream) out-stream
		 0 (string-output-stream-index in-stream))
  (setf (string-output-stream-index in-stream) 0))

;;;; Fill-pointer streams:
;;;
;;;    Fill pointer string output streams are not explicitly mentioned in
;;; the CLM, but they are required for the implementation of With-Output-To-String.

(defstruct (fill-pointer-output-stream
 	    (:include string-stream
		      (out #'fill-pointer-ouch)
		      (sout #'fill-pointer-sout)
		      (misc #'fill-pointer-misc))
	    (:print-function
	     (lambda (s stream d)
	       (declare (ignore s d))
	       (write-string "#<Fill-Pointer String Output Stream>" stream)))
	    (:constructor make-fill-pointer-output-stream (string)))
  ;; The string we throw stuff in.
  string)

 
(defun fill-pointer-ouch (stream character)
  (let* ((buffer (fill-pointer-output-stream-string stream))
	 (current (fill-pointer buffer))
	 (current+1 (1+ current)))
    (declare (fixnum current))
    (with-array-data ((workspace buffer) (start) (end))
      (declare (simple-string workspace))
      (let ((offset-current (+ start current)))
	(declare (fixnum offset-current))
	(if (= offset-current end)
	    (let* ((new-length (if (zerop current) 1 (* current 2)))
		   (new-workspace (make-string new-length)))
	      (declare (simple-string new-workspace))
	      (%primitive byte-blt workspace start new-workspace 0 current)
	      (setf workspace new-workspace)
	      (setf offset-current current)
	      (set-array-header buffer workspace new-length
				current+1 0 new-length nil))
	    (setf (fill-pointer buffer) current+1))
	(setf (schar workspace offset-current) character)))
    current+1))


(defun fill-pointer-sout (stream string start end)
  (declare (simple-string string) (fixnum start end))
  (let* ((buffer (fill-pointer-output-stream-string stream))
	 (current (fill-pointer buffer))
	 (string-len (- end start))
	 (dst-end (+ string-len current)))
    (declare (fixnum current dst-end string-len))
    (with-array-data ((workspace buffer) (dst-start) (dst-length))
      (declare (simple-string workspace))
      (let ((offset-dst-end (+ dst-start dst-end))
	    (offset-current (+ dst-start current)))
	(declare (fixnum offset-dst-end offset-current))
	(if (> offset-dst-end dst-length)
	    (let* ((new-length (+ (the fixnum (* current 2)) string-len))
		   (new-workspace (make-string new-length)))
	      (declare (simple-string new-workspace))
	      (%primitive byte-blt workspace dst-start new-workspace 0 current)
	      (setf workspace new-workspace)
	      (setf offset-current current)
	      (setf offset-dst-end dst-end)
	      (set-array-header buffer workspace new-length
				dst-end 0 new-length nil))
	    (setf (fill-pointer buffer) dst-end))
	(%primitive byte-blt string start
		    workspace offset-current offset-dst-end)))
    dst-end))


(defun fill-pointer-misc (stream operation &optional arg1 arg2)
  (declare (ignore arg1 arg2))
  (case operation
    (:charpos
     (let* ((buffer (fill-pointer-output-stream-string stream))
	    (current (fill-pointer buffer)))
       (with-array-data ((string buffer) (start) (end current))
	 (declare (simple-string string) (ignore start))
	 (let ((found (position #\newline string :test #'char=
				:end end :from-end t)))
	   (if found
	       (- end (the fixnum found))
	       current)))))
     (:element-type 'base-char)))

;;;; Indenting streams:

(defstruct (indenting-stream (:include lisp-stream
				       (out #'indenting-out)
				       (sout #'indenting-sout)
				       (misc #'indenting-misc))
			     (:print-function %print-indenting-stream)
			     (:constructor make-indenting-stream (stream)))
  ;; The stream we're based on:
  stream
  ;; How much we indent on each line:
  (indentation 0))

(setf (documentation 'make-indenting-stream 'function)
 "Returns an output stream which indents its output by some amount.")

(defun %print-indenting-stream (s stream d)
  (declare (ignore s d))
  (write-string "#<Indenting Stream>" stream))

;;; Indenting-Indent writes the right number of spaces needed to indent
;;; output on the given Stream based on the specified Sub-Stream.

(defmacro indenting-indent (stream sub-stream)
  `(do ((i 0 (+ i 60))
	(indentation (indenting-stream-indentation ,stream)))
       ((>= i indentation))
     (write-string*
      "                                                            "
      ,sub-stream 0 (min 60 (- indentation i)))))

;;; Indenting-Out writes a character to an indenting stream.

(defun indenting-out (stream char)
  (let ((sub-stream (indenting-stream-stream stream)))
    (write-char char sub-stream)
    (if (char= char #\newline)
	(indenting-indent stream sub-stream))))

;;; Indenting-Sout writes a string to an indenting stream.

(defun indenting-sout (stream string start end)
  (declare (simple-string string) (fixnum start end))
  (do ((i start)
       (sub-stream (indenting-stream-stream stream)))
      ((= i end))
    (let ((newline (position #\newline string :start i :end end)))
      (cond (newline
	     (write-string* string sub-stream i (1+ newline))
	     (indenting-indent stream sub-stream)
	     (setq i (+ newline 1)))
	    (t
	     (write-string* string sub-stream i end)
	     (setq i end))))))

;;; Indenting-Misc just treats just the :Line-Length message differently.
;;; Indenting-Charpos says the charpos is the charpos of the base stream minus
;;; the stream's indentation.

(defun indenting-misc (stream operation &optional arg1 arg2)
  (let ((sub-stream (indenting-stream-stream stream)))
    (if (lisp-stream-p sub-stream)
	(let ((method (lisp-stream-misc sub-stream)))
	  (case operation
	    (:line-length
	     (let ((line-length (funcall method sub-stream operation)))
	       (if line-length
		   (- line-length (indenting-stream-indentation stream)))))
	    (:charpos
	     (let ((charpos (funcall method sub-stream operation)))
	       (if charpos
		   (- charpos (indenting-stream-indentation stream)))))       
	    (t
	     (funcall method sub-stream operation arg1 arg2))))
	;; Fundamental-stream.
	(case operation
	  (:line-length
	   (let ((line-length (stream-line-length sub-stream)))
	     (if line-length
		 (- line-length (indenting-stream-indentation stream)))))
	  (:charpos
	   (let ((charpos (stream-line-column sub-stream)))
	     (if charpos
		 (- charpos (indenting-stream-indentation stream)))))
	  (t
	   (stream-misc-dispatch sub-stream operation arg1 arg2))))))


(declaim (maybe-inline read-char unread-char read-byte listen))



;;;; Case frobbing streams, used by format ~(...~).

(defstruct (case-frob-stream
	    (:include lisp-stream
		      (:misc #'case-frob-misc))
	    (:constructor %make-case-frob-stream (target out sout)))
  (target (required-argument) :type stream))

(defun make-case-frob-stream (target kind)
  "Returns a stream that sends all output to the stream TARGET, but modifies
   the case of letters, depending on KIND, which should be one of:
     :upcase - convert to upper case.
     :downcase - convert to lower case.
     :capitalize - convert the first letter of words to upper case and the
        rest of the word to lower case.
     :capitalize-first - convert the first letter of the first word to upper
        case and everything else to lower case."
  (declare (type stream target)
	   (type (member :upcase :downcase :capitalize :capitalize-first)
		 kind)
	   (values stream))
  (if (case-frob-stream-p target)
      ;; If we are going to be writing to a stream that already does case
      ;; frobbing, why bother frobbing the case just so it can frob it
      ;; again?
      target
      (multiple-value-bind
	  (out sout)
	  (ecase kind
	    (:upcase
	     (values #'case-frob-upcase-out
		     #'case-frob-upcase-sout))
	    (:downcase
	     (values #'case-frob-downcase-out
		     #'case-frob-downcase-sout))
	    (:capitalize
	     (values #'case-frob-capitalize-out
		     #'case-frob-capitalize-sout))
	    (:capitalize-first
	     (values #'case-frob-capitalize-first-out
		     #'case-frob-capitalize-first-sout)))
	(%make-case-frob-stream target out sout))))

(defun case-frob-misc (stream op &optional arg1 arg2)
  (declare (type case-frob-stream stream))
  (case op
    (:close)
    (t
     (let ((target (case-frob-stream-target stream)))
       (if (lisp-stream-p target)
	   (funcall (lisp-stream-misc target) target op arg1 arg2)
	   (stream-misc-dispatch target op arg1 arg2))))))

(defun case-frob-upcase-out (stream char)
  (declare (type case-frob-stream stream)
	   (type base-char char))
  (let ((target (case-frob-stream-target stream))
	(char (char-upcase char)))
    (if (lisp-stream-p target)
	(funcall (lisp-stream-out target) target char)
	(stream-write-char target char))))

(defun case-frob-upcase-sout (stream str start end)
  (declare (type case-frob-stream stream)
	   (type simple-base-string str)
	   (type index start)
	   (type (or index null) end))
  (let* ((target (case-frob-stream-target stream))
	 (len (length str))
	 (end (or end len))
	 (string (if (and (zerop start) (= len end))
		     (string-upcase str)
		     (nstring-upcase (subseq str start end))))
	 (string-len (- end start)))
    (if (lisp-stream-p target)
	(funcall (lisp-stream-sout target) target string 0 string-len)
	(stream-write-string target string 0 string-len))))

(defun case-frob-downcase-out (stream char)
  (declare (type case-frob-stream stream)
	   (type base-char char))
  (let ((target (case-frob-stream-target stream))
	(char (char-downcase char)))
    (if (lisp-stream-p target)
	(funcall (lisp-stream-out target) target char)
	(stream-write-char target char))))

(defun case-frob-downcase-sout (stream str start end)
  (declare (type case-frob-stream stream)
	   (type simple-base-string str)
	   (type index start)
	   (type (or index null) end))
  (let* ((target (case-frob-stream-target stream))
	 (len (length str))
	 (end (or end len))
	 (string (if (and (zerop start) (= len end))
		     (string-downcase str)
		     (nstring-downcase (subseq str start end))))
	 (string-len (- end start)))
    (if (lisp-stream-p target)
	(funcall (lisp-stream-sout target) target string 0 string-len)
	(stream-write-string target string 0 string-len))))

(defun case-frob-capitalize-out (stream char)
  (declare (type case-frob-stream stream)
	   (type base-char char))
  (let ((target (case-frob-stream-target stream)))
    (cond ((alphanumericp char)
	   (let ((char (char-upcase char)))
	     (if (lisp-stream-p target)
		 (funcall (lisp-stream-out target) target char)
		 (stream-write-char target char)))
	   (setf (case-frob-stream-out stream) #'case-frob-capitalize-aux-out)
	   (setf (case-frob-stream-sout stream)
		 #'case-frob-capitalize-aux-sout))
	  (t
	   (if (lisp-stream-p target)
	       (funcall (lisp-stream-out target) target char)
	       (stream-write-char target char))))))

(defun case-frob-capitalize-sout (stream str start end)
  (declare (type case-frob-stream stream)
	   (type simple-base-string str)
	   (type index start)
	   (type (or index null) end))
  (let* ((target (case-frob-stream-target stream))
	 (str (subseq str start end))
	 (len (length str))
	 (inside-word nil))
    (dotimes (i len)
      (let ((char (schar str i)))
	(cond ((not (alphanumericp char))
	       (setf inside-word nil))
	      (inside-word
	       (setf (schar str i) (char-downcase char)))
	      (t
	       (setf inside-word t)
	       (setf (schar str i) (char-upcase char))))))
    (when inside-word
      (setf (case-frob-stream-out stream)
	    #'case-frob-capitalize-aux-out)
      (setf (case-frob-stream-sout stream)
	    #'case-frob-capitalize-aux-sout))
    (if (lisp-stream-p target)
	(funcall (lisp-stream-sout target) target str 0 len)
	(stream-write-string target str 0 len))))

(defun case-frob-capitalize-aux-out (stream char)
  (declare (type case-frob-stream stream)
	   (type base-char char))
  (let ((target (case-frob-stream-target stream)))
    (cond ((alphanumericp char)
	   (let ((char (char-downcase char)))
	     (if (lisp-stream-p target)
		 (funcall (lisp-stream-out target) target char)
		 (stream-write-char target char))))
	  (t
	   (if (lisp-stream-p target)
	       (funcall (lisp-stream-out target) target char)
	       (stream-write-char target char))
	   (setf (case-frob-stream-out stream)
		 #'case-frob-capitalize-out)
	   (setf (case-frob-stream-sout stream)
		 #'case-frob-capitalize-sout)))))

(defun case-frob-capitalize-aux-sout (stream str start end)
  (declare (type case-frob-stream stream)
	   (type simple-base-string str)
	   (type index start)
	   (type (or index null) end))
  (let* ((target (case-frob-stream-target stream))
	 (str (subseq str start end))
	 (len (length str))
	 (inside-word t))
    (dotimes (i len)
      (let ((char (schar str i)))
	(cond ((not (alphanumericp char))
	       (setf inside-word nil))
	      (inside-word
	       (setf (schar str i) (char-downcase char)))
	      (t
	       (setf inside-word t)
	       (setf (schar str i) (char-upcase char))))))
    (unless inside-word
      (setf (case-frob-stream-out stream)
	    #'case-frob-capitalize-out)
      (setf (case-frob-stream-sout stream)
	    #'case-frob-capitalize-sout))
    (if (lisp-stream-p target)
	(funcall (lisp-stream-sout target) target str 0 len)
	(stream-write-string target str 0 len))))

(defun case-frob-capitalize-first-out (stream char)
  (declare (type case-frob-stream stream)
	   (type base-char char))
  (let ((target (case-frob-stream-target stream)))
    (cond ((alphanumericp char)
	   (let ((char (char-upcase char)))
	     (if (lisp-stream-p target)
		 (funcall (lisp-stream-out target) target char)
		 (stream-write-char target char)))
	   (setf (case-frob-stream-out stream)
		 #'case-frob-downcase-out)
	   (setf (case-frob-stream-sout stream)
		 #'case-frob-downcase-sout))
	  (t
	   (if (lisp-stream-p target)
	       (funcall (lisp-stream-out target) target char)
	       (stream-write-char target char))))))

(defun case-frob-capitalize-first-sout (stream str start end)
  (declare (type case-frob-stream stream)
	   (type simple-base-string str)
	   (type index start)
	   (type (or index null) end))
  (let* ((target (case-frob-stream-target stream))
	 (str (subseq str start end))
	 (len (length str)))
    (dotimes (i len)
      (let ((char (schar str i)))
	(when (alphanumericp char)
	  (setf (schar str i) (char-upcase char))
	  (do ((i (1+ i) (1+ i)))
	      ((= i len))
	    (setf (schar str i) (char-downcase (schar str i))))
	  (setf (case-frob-stream-out stream)
		#'case-frob-downcase-out)
	  (setf (case-frob-stream-sout stream)
		#'case-frob-downcase-sout)
	  (return))))
    (if (lisp-stream-p target)
	(funcall (lisp-stream-sout target) target str 0 len)
	(stream-write-string target str 0 len))))


;;;; Public interface from "EXTENSIONS" package.

(defstruct (stream-command (:print-function print-stream-command)
			   (:constructor make-stream-command
					 (name &optional args)))
  (name nil :type symbol)
  (args nil :type list))

(defun print-stream-command (obj str n)
  (declare (ignore n))
  (format str "#<Stream-Cmd ~S>" (stream-command-name obj)))


;;; GET-STREAM-COMMAND -- Public.
;;;
;;; We can't simply call the stream's misc method because nil is an
;;; ambiguous return value: does it mean text arrived, or does it mean the
;;; stream's misc method had no :get-command implementation.  We can't return
;;; nil until there is text input.  We don't need to loop because any stream
;;; implementing :get-command would wait until it had some input.  If the
;;; LISTEN fails, then we have some random stream we must wait on.
;;;
(defun get-stream-command (stream)
  "This takes a stream and waits for text or a command to appear on it.  If
   text appears before a command, this returns nil, and otherwise it returns
   a command."
  (let ((cmdp (funcall (lisp-stream-misc stream) stream :get-command)))
    (cond (cmdp)
	  ((listen stream)
	   nil)
	  (t
	   ;; This waits for input and returns nil when it arrives.
	   (unread-char (read-char stream) stream)))))


;;; READ-SEQUENCE --
;;; Note:  the multi-byte operation SYSTEM:READ-N-BYTES operates on
;;; subtypes of SIMPLE-ARRAY.  Hence the distinction between simple
;;; and non simple input functions.

(defun read-sequence (seq stream &key (start 0) (end nil) partial-fill)
  "Destructively modify SEQ by reading elements from STREAM.
SEQ is bounded by START and END. SEQ is destructively modified by
copying successive elements into it from STREAM. If the end of file
for STREAM is reached before copying all elements of the subsequence,
then the extra elements near the end of sequence are not updated.

Argument(s):
SEQ:	a proper SEQUENCE
STREAM:	an input STREAM
START:	a bounding index designator of type '(INTEGER 0 *)' (default 0)
END:	a bounding index designator which be NIL or an INTEGER of
	type '(INTEGER 0 *)' (default NIL)

Value(s):
POSITION: an INTEGER greater than or equal to zero, and less than or
          equal to the length of the SEQ. POSITION is the index of
          the first element of SEQ that was not updated, which might be
          less than END because the end of file was reached."

  (declare (type (or list vector) seq))	; could be (type sequence seq)
  (declare (type stream stream))
  (declare (type (integer 0 *) start))	; a list does not have a limit
  (declare (type (or null (integer 0 *)) end))
  (declare (values (integer 0 *)))

  (stream-dispatch stream
    ;; simple-stream
    (stream::%read-sequence stream seq start end partial-fill)
    ;; lisp-stream
    (let ((end (or end (length seq))))
      (declare (type (integer 0 *) start end))

      ;; Just catch some errors earlier than it would be necessary.
      (cond ((not (open-stream-p stream))
	     (error 'simple-stream-error
		    :stream stream
		    :format-control "The stream is not open."))
	    ((not (input-stream-p stream))
	     (error 'simple-stream-error
		    :stream stream
		    :format-control "The stream is not open for input."))
	    ((and seq (>= start end) 0))
	    (t
	     ;; So much for object-oriented programming!
	     (etypecase seq
	       (list
		(read-into-list seq stream start end))
	       (simple-string
		(read-into-simple-string seq stream start end))
	       (string
		(read-into-string seq stream start end))
	       (simple-array		; We also know that it is a 'vector'.
		(read-into-simple-array seq stream start end))
	       (vector
		(read-into-vector seq stream start end))))))
    ;; fundamental-stream
    (stream-read-sequence stream seq start end)))


;;; READ-INTO-LIST, READ-INTO-LIST-1
;;; Auxiliary functions for READ-SEQUENCE.  Their semantics is pretty
;;; obvious.  Since lists do not have an attached element type, and
;;; since we cannot do a low-level multi-byte read operation on them,
;;; I simply dispatch on the element type of the stream and then rely
;;; on READ-BYTE and READ-CHAR to to the input.
;;;
;;; NOTE: the use of 'endp' will generate a (desired)
;;; 'type-error' if the sequence is not a "proper list".

(defun read-into-list (l stream start end)
  (let ((read-function (if (subtypep (stream-element-type stream) 'character)
			   #'read-char
			   #'read-byte)))
    (read-into-list-1 (nthcdr start l) start end stream read-function)))

#+:recursive
(defun read-into-list-1 (l start end stream read-function)
  (declare (type list l))
  (declare (type stream stream))
  (declare (type (integer 0 *) start end))
  (if (or (endp l) (= start end))
      start
      (let* ((eof-marker (load-time-value (list 'eof-marker)))
             (el (funcall read-function stream nil eof-marker)))
	(cond ((eq el eof-marker) start)
	      (t (setf (first l) el)
		 (read-into-list-1 (rest l)
				   (1+ start)
				   end
				   stream
				   read-function))))
      ))


#-:iterative
(defun read-into-list-1 (l start end stream read-function)
  (declare (type list l))
  (declare (type stream stream))
  (declare (type (integer 0 *) start end))

  ;; The declaration for I may be too restrictive in the case of
  ;; lists.  But then again, it is still a huge number.
  (do ((lis l (rest lis))
       (i start (1+ i)))
      ((or (endp lis)
	   (>= i end))
       i)
    (declare (type list lis))
    (declare (type index i))
    (let* ((eof-marker (load-time-value (list 'eof-marker)))
           (el (funcall read-function stream nil eof-marker)))
      (when (eq el eof-marker)
	(return i))
      (setf (first lis) el))))


;;; READ-INTO-SIMPLE-STRING --

#+nil
(defun read-into-simple-string (s stream start end)
  (declare (type simple-string s))
  (declare (type stream stream))
  (declare (type index start end))
  (unless (subtypep (stream-element-type stream) 'character)
    (error 'type-error
	   :datum (read-char stream nil #\Null)
	   :expected-type (stream-element-type stream)
	   :format-control "Trying to read characters from a binary stream."))
  ;; Let's go as low level as it seems reasonable.
  (let* ((numbytes (- end start))
	 (total-bytes 0))
    ;; read-n-bytes may return fewer bytes than requested, so we need
    ;; to keep trying.
    (loop while (plusp numbytes) do
	  (let ((bytes-read (system:read-n-bytes stream s start numbytes nil)))
	    (when (zerop bytes-read)
	      (return-from read-into-simple-string start))
	    (incf total-bytes bytes-read)
	    (incf start bytes-read)
	    (decf numbytes bytes-read)))
    start))


;;; read-into-simple-string hacked to allow (unsigned-byte 8) stream-element-type
;;; For some reason applying this change to read-into-simple-string causes CMUCL to die.
(defun read-into-simple-string (s stream start end)
  (declare (type simple-string s))
  (declare (type stream stream))
  (declare (type index start end))
  (unless (or (subtypep (stream-element-type stream) 'character)
	      (equal (stream-element-type stream) '(unsigned-byte 8)))
    (error 'type-error
	   :datum (read-char stream nil #\Null)
	   :expected-type (stream-element-type stream)
	   :format-control "Trying to read characters from a binary stream."))
  ;; Let's go as low level as it seems reasonable.
  (let* ((numbytes (- end start))
	 (total-bytes 0))
    ;; read-n-bytes may return fewer bytes than requested, so we need
    ;; to keep trying.
    (loop while (plusp numbytes) do
      (let ((bytes-read (system:read-n-bytes stream s start numbytes nil)))
	(when (zerop bytes-read)
	  (return-from read-into-simple-string start))
	(incf total-bytes bytes-read)
	(incf start bytes-read)
	(decf numbytes bytes-read)))
    start))

(defun read-into-string (s stream start end)
  (declare (type string s))
  (declare (type stream stream))
  (declare (type index start end))
  (unless (subtypep (stream-element-type stream) 'character)
    (error 'type-error
	   :datum (read-char stream nil #\Null)
	   :expected-type (stream-element-type stream)
	   :format-control "Trying to read characters from a binary stream."))
  (do ((i start (1+ i))
       (s-len (length s)))
      ((or (>= i s-len)
	   (>= i end))
       i)
    (declare (type index i s-len))
    (let* ((eof-marker (load-time-value (list 'eof-marker)))
	   (el (read-char stream nil eof-marker)))
      (declare (type (or character stream) el))
      (when (eq el eof-marker)
	(return i))
      (setf (char s i) (the character el)))))


;;; READ-INTO-SIMPLE-ARRAY --
;;; We definitively know that we are really reading into a vector.

;;; *read-into-simple-array-recognized-types* --
;;;
;;; Note the new feature :extended-binary-streams.
;;; Up to 18a, CMUCL has a wired in limitation to treat only 8-bits
;;; word binary streams.  'fd-read-n-bytes' is associated to a binary
;;; stream only if the fd-stream has binary type size of 1 (i.e. 1
;;; 8-bits byte).  This is reflected also in the size of the input
;;; buffers.

(defparameter *read-into-simple-array-recognized-types*
  '((unsigned-byte 8)
    (unsigned-byte 16)
    (unsigned-byte 32)
    (signed-byte 8)
    (signed-byte 16)
    (signed-byte 32)
    single-float             ; not previously supported by read-sequence
    double-float             ; not previously supported by read-sequence
    ))

(defun read-into-simple-array (s stream start end)
  ;; The complex declaration is needed to make Python behave.
  ;; The first declaration does not work because of type promotion
  ;; which effectively excises the etypecase below.
  ;; The second declaration does not quite work because it does not
  ;; quite constrain the array element type.
  ;; (declare (type (simple-array (or unsigned-byte signed-byte) (*)) s))
  ;; (declare (type (simple-array * (*)) s))
  (declare (type (or (simple-array (unsigned-byte 8) (*))
		     (simple-array (signed-byte 8) (*))
		     (simple-array (unsigned-byte 16) (*))
		     (simple-array (signed-byte 16) (*))
		     (simple-array (unsigned-byte 32) (*))
		     (simple-array (signed-byte 32) (*))
		     (simple-array (unsigned-byte *) (*))
		     (simple-array (signed-byte *) (*))
		     (simple-array single-float (*))  ; not previously supported by read-sequence
		     (simple-array double-float (*))  ; not previously supported by read-sequence
		     simple-bit-vector)
		 s))

  (declare (type stream stream))
  (declare (type index start end))
  (let ((stream-et (stream-element-type stream)))
    ;; What is the purpose of this explicit test for characters?  It
    ;; prevents reading a string-stream into a vector, like the
    ;; example in the CLHS.
    (cond #+(or)
	  ((subtypep (stream-element-type stream) 'character)
	   (error 'type-error
		  :datum (read-byte stream nil 0)
		  :expected-type (stream-element-type stream) ; Bogus?!?
		  :format-control
		  "Trying to read binary data from a text stream."))

	  ;; Let's go as low level as it seems reasonable.
	  ((not (member stream-et
			*read-into-simple-array-recognized-types*
			:test #'equal))
	   ;; (format t ">>> Reading vector from binary stream of type ~S~%"
	   ;;         stream-et)
	   
	   ;; We resort to the READ-BYTE based operation.
	   (read-into-vector s stream start end))

	  ((/= vm:byte-bits 8)
	   ;; We must resort to the READ-BYTE based operation
	   ;; also in this case. XXX Unreachable code note.
	   (read-into-vector s stream start end))

	  ;; Otherwise we can do something more interesting.
	  (t
	   (labels
	       ((get-n-bytes (stream data offset numbytes)
		  ;; Handle case of read-n-bytes reading short.
		  (let ((need numbytes))
		    (loop
		      (let ((n (read-n-bytes stream data offset need nil)))
			(decf need n)
			(cond ((or (zerop need) ; Complete
				   (zerop n))   ; EOF
			       (return (- numbytes need)))
			      (t (incf offset n)))))))
		(read-n-x8-bytes (stream data offset-start offset-end byte-size)
		  (let* ((x8-mult (truncate byte-size 8))
			 (numbytes (* (- offset-end offset-start) x8-mult))
			 (bytes-read (get-n-bytes
				      stream
				      data
				      offset-start
				      numbytes))
			 )
		    ;; A check should probably be made here in order to
		    ;; be sure that we actually read the right amount
		    ;; of bytes. (I.e. (truncate bytes-read x8-mult)
		    ;; should return a 0 second value.
		    (if (< bytes-read numbytes)
			(+ offset-start (truncate bytes-read x8-mult))
			offset-end)))
		)
	     
	     ;; According to the definition of OPEN and READ-N-BYTES,
	     ;; these are the only cases when we can use the multi-byte read
	     ;; operation on a binary stream.
	     (with-array-data ((data s) (offset-start start) (offset-end end))
	       (etypecase data
		 ((simple-array (unsigned-byte 8) (*))
		  (read-n-x8-bytes stream data offset-start offset-end 8))
	    
		 ((simple-array (unsigned-byte 16) (*))
		  (read-n-x8-bytes stream data offset-start offset-end 16))
	    
		 ((simple-array (unsigned-byte 32) (*))
		  (read-n-x8-bytes stream data offset-start offset-end 32))

		 ((simple-array (signed-byte 8) (*))
		  (read-n-x8-bytes stream data offset-start offset-end 8))

		 ((simple-array (signed-byte 16) (*))
		  (read-n-x8-bytes stream data offset-start offset-end 16))

		 ((simple-array (signed-byte 32) (*))
		  (read-n-x8-bytes stream data offset-start offset-end 32))

		 ;; not previously supported by read-sequence
		 ((simple-array single-float (*))
		  (read-n-x8-bytes stream data offset-start offset-end 32))

		 ;; not previously supported by read-sequence
		 ((simple-array double-float (*))
		  (read-n-x8-bytes stream data offset-start offset-end 64))

		 ;; Otherwise we resort to the READ-BYTE based operation.
		 (simple-bit-vector
		  (read-into-vector s stream start end))
		 ((simple-array (unsigned-byte *) (*))
		  (read-into-vector s stream start end))
		 ((simple-array (signed-byte *) (*))
		  (read-into-vector s stream start end)))))))))


;;; READ-INTO-VECTOR --

(defun read-into-vector (v stream start end)
  (declare (type index start end))
  (declare (type stream stream))
  (declare (type vector v))
  (let* ((stream-et (stream-element-type stream))
	 (read-function (if (subtypep stream-et 'character)
			    #'read-char
			    #'read-byte)))
    (do ((i start (1+ i))
	 (a-len (length v)))
	((or (>= i a-len) (>= i end))
	 i)
      (declare (type index i a-len))
      (let* ((eof-marker (load-time-value (list 'eof-marker)))
	     (el (funcall read-function stream nil eof-marker)))
	(when (eq el eof-marker)
	  (return i))
	(setf (aref v i) el)))))

;(declaim (end-block))			; READ-SEQUENCE block


(declaim (start-block write-sequence))

;;; WRITE-SEQUENCE
;;; Why the type specifier '(list <type>)' was left out of the standard
;;; will always puzzle me.

(defun write-sequence (seq stream &key (start 0) (end nil))
  "Writes the elements of the of SEQ bounded by START and END to STREAM.
Argument(s):
SEQ:	a proper SEQUENCE
STREAM:	an output STREAM
START:	a bounding index designator of type '(INTEGER 0 *)' (default 0)
END:	a bounding index designator which be NIL or an INTEGER of
	type '(INTEGER 0 *)' (default NIL)

Value(s):
SEQ:	a proper SEQUENCE
"
  (declare (type (or list vector) seq))
  (declare (type stream stream))
  (declare (type (integer 0 *) start))	; a list does not have a limit
  (declare (type (or null (integer 0 *)) end))
  (declare (values (or list vector)))

  (stream-dispatch stream
    ;; simple-stream
    (stream::%write-sequence stream seq start end)
    ;; lisp-stream
    (let ((end (or end (length seq))))
      (declare (type (integer 0 *) start end))

      ;; Just catch some errors earlier than it would be necessary.
      (cond ((not (open-stream-p stream))
	     (error 'simple-stream-error
		    :stream stream
		    :format-control "The stream is not open."))
	    ((not (output-stream-p stream))
	     (error 'simple-stream-error
		    :stream stream
		    :format-control "The stream is not open for output."))
	    ((and seq (>= start end)) seq)
	    (t
	     ;; So much for object-oriented programming!
	     ;; Note: order of type clauses is very important.  As a
	     ;; matter of fact it is patterned after the class
	     ;; precedence list of each of the types listed.
	     (etypecase seq
	       (list
		(write-list-out seq stream start end))
	       (simple-string
		(write-simple-string-out seq stream start end))
	       (string
		(write-string-out seq stream start end))
	       (simple-vector		; This is necessary because of
					; the underlying behavior of
					; OUTPUT-RAW-BYTES.  A vector
					; produced by VECTOR has
					; element-type T in CMUCL.
		(write-vector-out seq stream start end))
	       (simple-array		; We know it is also a vector!
		(write-simple-array-out seq stream start end))
	       (vector
		(write-vector-out seq stream start end)))
	     )))
    ;; fundamental-stream
    (stream-write-sequence stream seq start end))
  seq)


;;; The following functions operate under one - possibly wrong -
;;; assumption.  CMUCL seems smart enough to collapse arrays of
;;; characters onto strings (i.e. it does the right thing.)  Hence,
;;; when each function is called, we are pretty safe in assuming that
;;; the stream element type and the sequence element type are what we
;;; expect.

;;; WRITE-LIST-OUT

(defun write-list-out (seq stream start end)
  ;; I wish I could say
  ;; (declare (type (list (or character (unsigned-byte 32))) seq))
  (declare (type list seq))
  (declare (type (integer 0 *) start end))
  (declare (type stream stream))

  (flet ((check-list-element-types (l type)
	   (declare (list l))
	   (dolist (e l)
	     (unless (typep e type)
	       (error 'type-error
		      :datum e
		      :expected-type type
		      :format-control
		      "Trying to output an element of unproper type to a stream.")))))
    (let ((stream-et (stream-element-type stream)))

      (check-list-element-types seq stream-et)
      (let ((write-function (if (subtypep stream-et 'character)
				#'write-char
				#'write-byte)))

	;; According to Rob MacLachlan <Rob_MacLachlan@ADDER.SLISP.CS.CMU.EDU>
	;; It would make sense to write everything to a string and
	;; then call 'write-string' no matter what the type of the
	;; stream.
	;; This implementation should be something like:
	;;
	;; (let ((temp-string (format nil "~{~W~}" (subseq seq start end))))
	;;    (write-string temp-string stream)
	;;
	;; Of course this seems a little expensive and a better
	;; iterative solution could be used instead.
	;;
	;; Anyway.  For the time being, the loop seems ok, given that
	;; lists will most likely not used that much for buffered I/O.
	
	(do ((lis (nthcdr start seq) (rest lis))
	     (i start (1+ i))
	     )
	    ((or (endp lis) (>= i end)) seq)
	  (declare (type list lis))
	  (declare (type index i))
	  (funcall write-function (first lis) stream))))
    ))


;;; WRITE-SIMPLE-STRING-OUT, WRITE-STRING-OUT
;;; These functions are really the same, since they rely on
;;; WRITE-STRING (which should be pretty efficient by itself.)  The
;;; only difference is in the declaration. Maybe the duplication is an
;;; overkill, but it makes things a little more logical.

(defun write-simple-string-out (seq stream start end)
  (declare (type simple-string seq))
  (when (and (not (subtypep (stream-element-type stream) 'character))
	     (not (equal (stream-element-type stream) '(unsigned-byte 8))))
    (error 'type-error
	   :datum seq
	   :expected-type (stream-element-type stream)
	   :format-control "Trying to output a string to a binary stream."))
  (write-string seq stream :start start :end end)
  seq)


(defun write-string-out (seq stream start end)
  (declare (type string seq))
  (when (and (not (subtypep (stream-element-type stream) 'character))
	     (not (equal (stream-element-type stream) '(unsigned-byte 8))))
    (error 'type-error
	   :datum seq
	   :expected-type (stream-element-type stream)
	   :format-control "Trying to output a string to a binary stream."))
  (write-string seq stream :start start :end end)
  seq)


;;; WRITE-SIMPLE-ARRAY-OUT, WRITE-VECTOR-OUT --
;;; The main difference is that for simple vectors, we can use the
;;; very efficient SYSTEM:OUTPUT-RAW-BYTES on FD-STREAMS.
;;; (OUTPUT-RAW-BYTES seems to assume to receive a SIMPLE-ARRAY.)
;;;
;;; Again, Rob MacLachlan suggestion would be to first write
;;; everything out to a string and then to use WRITE-STRING. (See comment
;;; within WRITE-LIST-OUT.)

(defun write-simple-array-out (seq stream start end)
   ;; The complex declaration is needed to make Python behave.
  ;; The first declaration does not work because of type promotion
  ;; which effectively excises the etypecase below.
  ;; The second declaration does not quite work because it does not
  ;; quite constrain the array element type.
  ;; (declare (type (simple-array (or unsigned-byte signed-byte) (*)) s))
  ;; (declare (type (simple-array * (*)) s))
  (declare (type (or (simple-array (unsigned-byte 8) (*))
		     (simple-array (signed-byte 8) (*))
		     (simple-array (unsigned-byte 16) (*))
		     (simple-array (signed-byte 16) (*))
		     (simple-array (unsigned-byte 32) (*))
		     (simple-array (signed-byte 32) (*))
		     (simple-array (unsigned-byte *) (*))
		     (simple-array (signed-byte *) (*))
		     (simple-array single-float (*))
		     (simple-array double-float (*)))		 
		    seq))
  (when (not (subtypep (stream-element-type stream) 'integer))
    (error 'type-error
	   :datum (elt seq 0)
	   :expected-type (stream-element-type stream)
	   :format-control "Trying to output binary data to a text stream."))
  (cond ((system:fd-stream-p stream)
	 (flet ((write-n-x8-bytes (stream data start end byte-size)
		  (let ((x8-mult (truncate byte-size 8)))
		    (system:output-raw-bytes stream data
					     (* x8-mult start)
					     (* x8-mult end)))))
	   (with-array-data ((data seq)
			     (start start)
			     (end   end))
	     (etypecase data
	       ((simple-array (unsigned-byte 8) (*))
		(write-n-x8-bytes stream data start end 8))

	       ((simple-array (unsigned-byte 16) (*))
		(write-n-x8-bytes stream data start end 16))

	       ((simple-array (unsigned-byte 32) (*))
		(write-n-x8-bytes stream data start end 32))

	       ((simple-array (signed-byte 8) (*))
		(write-n-x8-bytes stream data start end 8))

	       ((simple-array (signed-byte 16) (*))
		(write-n-x8-bytes stream data start end 16))

	       ((simple-array (signed-byte 32) (*))
		(write-n-x8-bytes stream data start end 32))

	       ((simple-array single-float (*))
		(write-n-x8-bytes stream data start end 32))

	       ((simple-array double-float (*))
		(write-n-x8-bytes stream data start end 64))

	       ;; Otherwise we resort to the READ-BYTE based operation.
	       ((simple-array (unsigned-byte *) (*))
		(write-vector-out seq stream start end))

	       ((simple-array (signed-byte *) (*))
		(write-vector-out seq stream start end))

	       (bit-vector
		(write-vector-out seq stream start end))
	       )
	     seq)))

	(t (do ((i start (1+ i))
		(sv-len (length seq))
		)
	       ((or (>= i end) (>= i sv-len)) seq)
	     (declare (type index i sv-len))
	     (write-byte (aref seq i) stream)))))

(defun write-vector-out (seq stream start end)
  (let ((write-function
         (if (subtypep (stream-element-type stream) 'character)
             #'write-char
             #'write-byte)))
    (do ((i start (1+ i))
         (a-len (length seq))
         )
        ((or (>= i end) (>= i a-len)) seq)
      (declare (type index i a-len))
      (funcall write-function (aref seq i) stream))))

(declaim (end-block))			; WRITE-SEQUENCE block.
#||
;;; READ-SEQUENCE -- Public
;;;
(defun read-sequence (seq stream &key (start 0) (end nil))
  "Destructively modify SEQ by reading elements from STREAM.
  SEQ is bounded by START and END. SEQ is destructively modified by
  copying successive elements into it from STREAM. If the end of file
  for STREAM is reached before copying all elements of the subsequence,
  then the extra elements near the end of sequence are not updated, and
  the index of the next element is returned."
  (declare (type sequence seq)
	   (type stream stream)
	   (type index start)
	   (type sequence-end end)
	   (values index))
  (when (not (lisp::lisp-stream-p stream))
     (return-from read-sequence (stream-read-sequence seq stream start end)))
  (let ((end (or end (length seq))))
    (declare (type index end))
    (etypecase seq
      (list
       (let ((read-function
	      (if (subtypep (stream-element-type stream) 'character)
		  #'read-char
		  #'read-byte)))
	 (do ((rem (nthcdr start seq) (rest rem))
	      (i start (1+ i)))
	     ((or (endp rem) (>= i end)) i)
	   (declare (type list rem)
		    (type index i))
	   (let ((el (funcall read-function stream nil :eof)))
	     (when (eq el :eof)
	       (return i))
	     (setf (first rem) el)))))
      (vector
       (with-array-data ((data seq) (offset-start start) (offset-end end))
	 (typecase data
	   ((or (simple-array (unsigned-byte 8) (*))
		(simple-array (signed-byte 8) (*))
		simple-string)
	    (let ((required (- end start)))
	      (loop
	       (let ((bytes-read (system:read-n-bytes stream data offset-start
						      required nil)))
		 (cond ((= bytes-read required)
			(return end))
		       ((zerop bytes-read)
			(return (- end required)))
		       (t
			(decf required bytes-read)
			(incf offset-start bytes-read)))))))
	   (t
	    (let ((read-function
		   (if (subtypep (stream-element-type stream) 'character)
		       #'read-char
		       #'read-byte)))
	      (do ((i offset-start (1+ i)))
		  ((>= i offset-end) end)
		(declare (type index i))
		(let ((el (funcall read-function stream nil :eof)))
		  (when (eq el :eof)
		    (return (+ start (- i offset-start))))
		  (setf (aref data i) el)))))))))))

;;; WRITE-SEQUENCE -- Public
;;;
(defun write-sequence (seq stream &key (start 0) (end nil))
  "Write the elements of SEQ bounded by START and END to STREAM."
  (declare (type sequence seq)
	   (type stream stream)
	   (type index start)
	   (type sequence-end end)
	   (values sequence))
  (when (not (lisp::lisp-stream-p stream))
    (return-from write-sequence (stream-write-sequence seq stream start end)))
  (let ((end (or end (length seq))))
    (declare (type index start end))
    (etypecase seq
      (list
       (let ((write-function
	      (if (subtypep (stream-element-type stream) 'character)
		  #'write-char
		  #'write-byte)))
	 (do ((rem (nthcdr start seq) (rest rem))
	      (i start (1+ i)))
	     ((or (endp rem) (>= i end)) seq)
	   (declare (type list rem)
		    (type index i))
	   (funcall write-function (first rem) stream))))
      (string
       (write-string* seq stream start end))
      (vector
       (let ((write-function
	      (if (subtypep (stream-element-type stream) 'character)
		  #'write-char
		  #'write-byte)))
	 (do ((i start (1+ i)))
	     ((>= i end) seq)
	   (declare (type index i))
	   (funcall write-function (aref seq i) stream)))))))
||#


;;; finish-standard-output-streams  --  Public
;;;
;;; Finish output on some of the standard output streams.
;;;
(defun finish-standard-output-streams ()
  (dolist (stream '(*standard-output* *error-output* *trace-output*))
    (when (boundp stream)
      (let ((stream (symbol-value stream)))
	(when (and (streamp stream) (open-stream-p stream))
	  (finish-output stream))))))
