;;;; This file implements The MD5 Message-Digest Algorithm, as defined in
;;;; RFC 1321 by R. Rivest, published April 1992.
;;;;
;;;; It was written by Pierre R. Mai, with copious input from the
;;;; cmucl-help mailing-list hosted at cons.org, in November 2001 and
;;;; has been placed into the public domain.
;;;;
;;;; $Id: md5.lisp,v 1.3 2003/09/16 12:07:39 crhodes Exp $
;;;;
;;;; While the implementation should work on all conforming Common
;;;; Lisp implementations, it has only been optimized for CMU CL,
;;;; where it achieved comparable performance to the standard md5sum
;;;; utility (within a factor of 1.5 or less on iA32 and UltraSparc
;;;; hardware).
;;;;
;;;; Since the implementation makes heavy use of arithmetic on
;;;; (unsigned-byte 32) numbers, acceptable performance is likely only
;;;; on CL implementations that support unboxed arithmetic on such
;;;; numbers in some form.  For other CL implementations a 16bit
;;;; implementation of MD5 is probably more suitable.
;;;;
;;;; The code implements correct operation for files of unbounded size
;;;; as is, at the cost of having to do a single generic integer
;;;; addition for each call to update-md5-state.  If you call
;;;; update-md5-state frequently with little data, this can pose a
;;;; performance problem.  If you can live with a size restriction of
;;;; 512 MB, then you can enable fast fixnum arithmetic by putting
;;;; :md5-small-length onto *features* prior to compiling this file.
;;;;
;;;; This software is "as is", and has no warranty of any kind.  The
;;;; authors assume no responsibility for the consequences of any use
;;;; of this software.

(defpackage :SB-MD5 (:use :CL)
  (:export
   ;; Low-Level types and functions
   #:md5-regs #:initial-md5-regs #:md5regs-digest
   #:update-md5-block #:fill-block #:fill-block-ub8 #:fill-block-char
   ;; Mid-Level types and functions
   #:md5-state #:md5-state-p #:make-md5-state
   #:update-md5-state #:finalize-md5-state
   ;; High-Level functions on sequences, streams and files
   #:md5sum-sequence #:md5sum-stream #:md5sum-file))

(in-package :SB-MD5)

#+cmu
(eval-when (:compile-toplevel)
  (defparameter *old-expansion-limit* ext:*inline-expansion-limit*)
  (setq ext:*inline-expansion-limit* (max ext:*inline-expansion-limit* 1000)))

#+cmu
(eval-when (:compile-toplevel :execute)
  (defparameter *old-features* *features*)
  (pushnew (c:backend-byte-order c:*target-backend*) *features*))

#+sbcl
(eval-when (:compile-toplevel)
  (defparameter *old-features* *features*)
  (pushnew sb-c:*backend-byte-order* *features*))

;;; Section 2:  Basic Datatypes

(deftype ub32 ()
  "Corresponds to the 32bit quantity word of the MD5 Spec"
  `(unsigned-byte 32))

(defmacro assemble-ub32 (a b c d)
  "Assemble an ub32 value from the given (unsigned-byte 8) values,
where a is the intended low-order byte and d the high-order byte."
  `(the ub32 (logior (ash ,d 24) (ash ,c 16) (ash ,b 8) ,a)))

;;; Section 3.4:  Auxilliary functions

(declaim (inline f g h i)
	 (ftype (function (ub32 ub32 ub32) ub32) f g h i))

(defun f (x y z)
  (declare (type ub32 x y z)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  #+cmu
  (kernel:32bit-logical-or (kernel:32bit-logical-and x y)
			   (kernel:32bit-logical-andc1 x z))
  #-cmu
  (logior (logand x y) (logandc1 x z)))

(defun g (x y z)
  (declare (type ub32 x y z)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  #+cmu
  (kernel:32bit-logical-or (kernel:32bit-logical-and x z)
			   (kernel:32bit-logical-andc2 y z))
  #-cmu
  (logior (logand x z) (logandc2 y z)))

(defun h (x y z)
  (declare (type ub32 x y z)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  #+cmu
  (kernel:32bit-logical-xor x (kernel:32bit-logical-xor y z))
  #-cmu
  (logxor x y z))

(defun i (x y z)
  (declare (type ub32 x y z)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  #+cmu
  (kernel:32bit-logical-xor y (kernel:32bit-logical-orc2 x z))
  #-cmu
  (ldb (byte 32 0) (logxor y (logorc2 x z))))

(declaim (inline mod32+)
	 (ftype (function (ub32 ub32) ub32) mod32+))
(defun mod32+ (a b)
  (declare (type ub32 a b) (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  (ldb (byte 32 0) (+ a b)))

#+cmu
(define-compiler-macro mod32+ (a b)
  `(ext:truly-the ub32 (+ ,a ,b)))

;;; Dunno why we need this, but without it MOD32+ wasn't being
;;; inlined.  Oh well.  -- CSR, 2003-09-14
#+sbcl
(define-compiler-macro mod32+ (a b)
  `(ldb (byte 32 0) (+ ,a ,b)))

(declaim (inline rol32)
	 (ftype (function (ub32 (unsigned-byte 5)) ub32) rol32))
(defun rol32 (a s)
  (declare (type ub32 a) (type (unsigned-byte 5) s)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  #+cmu
  (kernel:32bit-logical-or #+little-endian (kernel:shift-towards-end a s)
			   #+big-endian (kernel:shift-towards-start a s)
			   (ash a (- s 32)))
  #+sbcl
  (sb-rotate-byte:rotate-byte s (byte 32 0) a)
  #-(or cmu sbcl)
  (logior (ldb (byte 32 0) (ash a s)) (ash a (- s 32))))

;;; Section 3.4:  Table T

(eval-when (:compile-toplevel :load-toplevel :execute)
  (defparameter *t* (make-array 64 :element-type 'ub32
				:initial-contents
				(loop for i from 1 to 64
				      collect
				      (truncate
				       (* 4294967296
					  (abs (sin (float i 0.0d0)))))))))

;;; Section 3.4:  Helper Macro for single round definitions

(defmacro with-md5-round ((op block) &rest clauses)
  (loop for (a b c d k s i) in clauses
	collect
	`(setq ,a (mod32+ ,b (rol32 (mod32+ (mod32+ ,a (,op ,b ,c ,d))
					    (mod32+ (aref ,block ,k)
						    ,(aref *t* (1- i))))
			            ,s)))
	into result
	finally
	(return `(progn ,@result))))

;;; Section 3.3:  (Initial) MD5 Working Set

(deftype md5-regs ()
  "The working state of the MD5 algorithm, which contains the 4 32-bit
registers A, B, C and D."
  `(simple-array (unsigned-byte 32) (4)))

(defmacro md5-regs-a (regs)
  `(aref ,regs 0))

(defmacro md5-regs-b (regs)
  `(aref ,regs 1))

(defmacro md5-regs-c (regs)
  `(aref ,regs 2))

(defmacro md5-regs-d (regs)
  `(aref ,regs 3))

(defconstant +md5-magic-a+ (assemble-ub32 #x01 #x23 #x45 #x67)
  "Initial value of Register A of the MD5 working state.")
(defconstant +md5-magic-b+ (assemble-ub32 #x89 #xab #xcd #xef)
  "Initial value of Register B of the MD5 working state.")
(defconstant +md5-magic-c+ (assemble-ub32 #xfe #xdc #xba #x98)
  "Initial value of Register C of the MD5 working state.")
(defconstant +md5-magic-d+ (assemble-ub32 #x76 #x54 #x32 #x10)
  "Initial value of Register D of the MD5 working state.")

(declaim (inline initial-md5-regs))
(defun initial-md5-regs ()
  "Create the initial working state of an MD5 run."
  (declare (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  (let ((regs (make-array 4 :element-type '(unsigned-byte 32))))
    (declare (type md5-regs regs))
    (setf (md5-regs-a regs) +md5-magic-a+
	  (md5-regs-b regs) +md5-magic-b+
	  (md5-regs-c regs) +md5-magic-c+
	  (md5-regs-d regs) +md5-magic-d+)
    regs))

;;; Section 3.4:  Operation on 16-Word Blocks

(defun update-md5-block (regs block)
  "This is the core part of the MD5 algorithm.  It takes a complete 16
word block of input, and updates the working state in A, B, C, and D
accordingly."
  (declare (type md5-regs regs)
	   (type (simple-array ub32 (16)) block)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  (let ((a (md5-regs-a regs)) (b (md5-regs-b regs))
	(c (md5-regs-c regs)) (d (md5-regs-d regs)))
    (declare (type ub32 a b c d))
    ;; Round 1
    (with-md5-round (f block)
      (A B C D  0  7  1)(D A B C  1 12  2)(C D A B  2 17  3)(B C D A  3 22  4)
      (A B C D  4  7  5)(D A B C  5 12  6)(C D A B  6 17  7)(B C D A  7 22  8)
      (A B C D  8  7  9)(D A B C  9 12 10)(C D A B 10 17 11)(B C D A 11 22 12)
      (A B C D 12  7 13)(D A B C 13 12 14)(C D A B 14 17 15)(B C D A 15 22 16))
    ;; Round 2
    (with-md5-round (g block)
      (A B C D  1  5 17)(D A B C  6  9 18)(C D A B 11 14 19)(B C D A  0 20 20)
      (A B C D  5  5 21)(D A B C 10  9 22)(C D A B 15 14 23)(B C D A  4 20 24)
      (A B C D  9  5 25)(D A B C 14  9 26)(C D A B  3 14 27)(B C D A  8 20 28)
      (A B C D 13  5 29)(D A B C  2  9 30)(C D A B  7 14 31)(B C D A 12 20 32))
    ;; Round 3
    (with-md5-round (h block)
      (A B C D  5  4 33)(D A B C  8 11 34)(C D A B 11 16 35)(B C D A 14 23 36)
      (A B C D  1  4 37)(D A B C  4 11 38)(C D A B  7 16 39)(B C D A 10 23 40)
      (A B C D 13  4 41)(D A B C  0 11 42)(C D A B  3 16 43)(B C D A  6 23 44)
      (A B C D  9  4 45)(D A B C 12 11 46)(C D A B 15 16 47)(B C D A  2 23 48))
    ;; Round 4
    (with-md5-round (i block)
      (A B C D  0  6 49)(D A B C  7 10 50)(C D A B 14 15 51)(B C D A  5 21 52)
      (A B C D 12  6 53)(D A B C  3 10 54)(C D A B 10 15 55)(B C D A  1 21 56)
      (A B C D  8  6 57)(D A B C 15 10 58)(C D A B  6 15 59)(B C D A 13 21 60)
      (A B C D  4  6 61)(D A B C 11 10 62)(C D A B  2 15 63)(B C D A  9 21 64))
    ;; Update and return
    (setf (md5-regs-a regs) (mod32+ (md5-regs-a regs) a)
	  (md5-regs-b regs) (mod32+ (md5-regs-b regs) b)
	  (md5-regs-c regs) (mod32+ (md5-regs-c regs) c)
	  (md5-regs-d regs) (mod32+ (md5-regs-d regs) d))
    regs))

;;; Section 3.4:  Converting 8bit-vectors into 16-Word Blocks

(declaim (inline fill-block fill-block-ub8 fill-block-char))
(defun fill-block (block buffer offset)
  "Convert a complete 64 byte input vector segment into the given 16
word MD5 block.  This currently works on (unsigned-byte 8) and
character simple-arrays, via the functions `fill-block-ub8' and
`fill-block-char' respectively."
  (declare (type (integer 0 #.(- most-positive-fixnum 64)) offset)
	   (type (simple-array ub32 (16)) block)
	   (type (simple-array * (*)) buffer)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  (etypecase buffer
    ((simple-array (unsigned-byte 8) (*))
     (fill-block-ub8 block buffer offset))
    (simple-string
     (fill-block-char block buffer offset))))

(defun fill-block-ub8 (block buffer offset)
  "Convert a complete 64 (unsigned-byte 8) input vector segment
starting from offset into the given 16 word MD5 block."
  (declare (type (integer 0 #.(- most-positive-fixnum 64)) offset)
	   (type (simple-array ub32 (16)) block)
	   (type (simple-array (unsigned-byte 8) (*)) buffer)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  #+(and :cmu :little-endian)
  (kernel:bit-bash-copy
   buffer (+ (* vm:vector-data-offset vm:word-bits) (* offset vm:byte-bits))
   block (* vm:vector-data-offset vm:word-bits)
   (* 64 vm:byte-bits))
  #+(and :sbcl :little-endian)
  (sb-kernel:bit-bash-copy
   buffer (+ (* sb-vm:vector-data-offset sb-vm:n-word-bits)
	     (* offset sb-vm:n-byte-bits))
   block (* sb-vm:vector-data-offset sb-vm:n-word-bits)
   (* 64 sb-vm:n-byte-bits))
  #-(or (and :sbcl :little-endian) (and :cmu :little-endian))
  (loop for i of-type (integer 0 16) from 0
	for j of-type (integer 0 #.most-positive-fixnum)
	from offset to (+ offset 63) by 4
	do
	(setf (aref block i)
	      (assemble-ub32 (aref buffer j)
			     (aref buffer (+ j 1))
			     (aref buffer (+ j 2))
			     (aref buffer (+ j 3))))))

(defun fill-block-char (block buffer offset)
  "Convert a complete 64 character input string segment starting from
offset into the given 16 word MD5 block."
  (declare (type (integer 0 #.(- most-positive-fixnum 64)) offset)
	   (type (simple-array ub32 (16)) block)
	   (type simple-string buffer)
	   (optimize (speed 3) (safety 0) (space 0) (debug 0)))
  #+(and :cmu :little-endian)
  (kernel:bit-bash-copy
   buffer (+ (* vm:vector-data-offset vm:word-bits) (* offset vm:byte-bits))
   block (* vm:vector-data-offset vm:word-bits)
   (* 64 vm:byte-bits))
  #+(and :sbcl :little-endian)
  (sb-kernel:bit-bash-copy
   buffer (+ (* sb-vm:vector-data-offset sb-vm:n-word-bits)
	     (* offset sb-vm:n-byte-bits))
   block (* sb-vm:vector-data-offset sb-vm:n-word-bits)
   (* 64 sb-vm:n-byte-bits))
  #-(or (and :sbcl :little-endian) (and :cmu :little-endian))
  (loop for i of-type (integer 0 16) from 0
	for j of-type (integer 0 #.most-positive-fixnum)
	from offset to (+ offset 63) by 4
	do
	(setf (aref block i)
	      (assemble-ub32 (char-code (schar buffer j))
			     (char-code (schar buffer (+ j 1)))
			     (char-code (schar buffer (+ j 2)))
			     (char-code (schar buffer (+ j 3)))))))

;;; Section 3.5:  Message Digest Output

(declaim (inline md5regs-digest))
(defun md5regs-digest (regs)
  "Create the final 16 byte message-digest from the MD5 working state
in regs.  Returns a (simple-array (unsigned-byte 8) (16))."
  (declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
	   (type md5-regs regs))
  (let ((result (make-array 16 :element-type '(unsigned-byte 8))))
    (declare (type (simple-array (unsigned-byte 8) (16)) result))
    (macrolet ((frob (reg offset)
		 (let ((var (gensym)))
		   `(let ((,var ,reg))
		      (declare (type ub32 ,var))
		      (setf
		       (aref result ,offset) (ldb (byte 8 0) ,var)
		       (aref result ,(+ offset 1)) (ldb (byte 8 8) ,var)
		       (aref result ,(+ offset 2)) (ldb (byte 8 16) ,var)
		       (aref result ,(+ offset 3)) (ldb (byte 8 24) ,var))))))
      (frob (md5-regs-a regs) 0)
      (frob (md5-regs-b regs) 4)
      (frob (md5-regs-c regs) 8)
      (frob (md5-regs-d regs) 12))
    result))

;;; Mid-Level Drivers

(defstruct (md5-state
	     (:constructor make-md5-state ())
	     (:copier))
  (regs (initial-md5-regs) :type md5-regs :read-only t)
  (amount 0 :type
	  #-md5-small-length (integer 0 *)
	  #+md5-small-length (unsigned-byte 29))
  (block (make-array 16 :element-type '(unsigned-byte 32)) :read-only t
	 :type (simple-array (unsigned-byte 32) (16)))
  (buffer (make-array 64 :element-type '(unsigned-byte 8)) :read-only t
	 :type (simple-array (unsigned-byte 8) (64)))
  (buffer-index 0 :type (integer 0 63))
  (finalized-p nil))

(declaim (inline copy-to-buffer))
(defun copy-to-buffer (from from-offset count buffer buffer-offset)
  "Copy a partial segment from input vector from starting at
from-offset and copying count elements into the 64 byte buffer
starting at buffer-offset."
  (declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
	   (type (unsigned-byte 29) from-offset)
	   (type (integer 0 63) count buffer-offset)
	   (type (simple-array * (*)) from)
	   (type (simple-array (unsigned-byte 8) (64)) buffer))
  #+cmu
  (kernel:bit-bash-copy
   from (+ (* vm:vector-data-offset vm:word-bits) (* from-offset vm:byte-bits))
   buffer (+ (* vm:vector-data-offset vm:word-bits)
	     (* buffer-offset vm:byte-bits))
   (* count vm:byte-bits))
  #+sbcl
  (sb-kernel:bit-bash-copy
   from (+ (* sb-vm:vector-data-offset sb-vm:n-word-bits)
	   (* from-offset sb-vm:n-byte-bits))
   buffer (+ (* sb-vm:vector-data-offset sb-vm:n-word-bits)
	     (* buffer-offset sb-vm:n-byte-bits))
   (* count sb-vm:n-byte-bits))
  #-(or cmu sbcl)
  (etypecase from
    (simple-string
     (loop for buffer-index of-type (integer 0 64) from buffer-offset
	   for from-index of-type fixnum from from-offset
	   below (+ from-offset count)
	   do
	   (setf (aref buffer buffer-index)
		 (char-code (schar (the simple-string from) from-index)))))
    ((simple-array (unsigned-byte 8) (*))
     (loop for buffer-index of-type (integer 0 64) from buffer-offset
	   for from-index of-type fixnum from from-offset
	   below (+ from-offset count)
	   do
	   (setf (aref buffer buffer-index)
		 (aref (the (simple-array (unsigned-byte 8) (*)) from)
		       from-index))))))

(defun update-md5-state (state sequence &key (start 0) (end (length sequence)))
  "Update the given md5-state from sequence, which is either a
simple-string or a simple-array with element-type (unsigned-byte 8),
bounded by start and end, which must be numeric bounding-indices."
  (declare (type md5-state state)
	   (type (simple-array * (*)) sequence)
	   (type fixnum start end)
	   (optimize (speed 3) #+(or cmu sbcl) (safety 0) (space 0) (debug 0))
	   #+cmu
	   (ext:optimize-interface (safety 1) (debug 1)))
  (let ((regs (md5-state-regs state))
	(block (md5-state-block state))
	(buffer (md5-state-buffer state))
	(buffer-index (md5-state-buffer-index state))
	(length (- end start)))
    (declare (type md5-regs regs) (type fixnum length)
	     (type (integer 0 63) buffer-index)
	     (type (simple-array (unsigned-byte 32) (16)) block)
	     (type (simple-array (unsigned-byte 8) (64)) buffer))
    ;; Handle old rest
    (unless (zerop buffer-index)
      (let ((amount (min (- 64 buffer-index) length)))
	(declare (type (integer 0 63) amount))
	(copy-to-buffer sequence start amount buffer buffer-index)
	(setq start (the fixnum (+ start amount)))
	(when (>= start end)
	  (setf (md5-state-buffer-index state) (+ buffer-index amount))
	  (return-from update-md5-state state)))
      (fill-block-ub8 block buffer 0)
      (update-md5-block regs block))
    ;; Handle main-part and new-rest
    (etypecase sequence
      ((simple-array (unsigned-byte 8) (*))
       (locally
	   (declare (type (simple-array (unsigned-byte 8) (*)) sequence))
	 (loop for offset of-type (unsigned-byte 29) from start below end by 64
	       until (< (- end offset) 64)
	       do
	       (fill-block-ub8 block sequence offset)
	       (update-md5-block regs block)
	       finally
	       (let ((amount (- end offset)))
		 (unless (zerop amount)
		   (copy-to-buffer sequence offset amount buffer 0))
		 (setf (md5-state-buffer-index state) amount)))))
      (simple-string
       (locally
	   (declare (type simple-string sequence))
	 (loop for offset of-type (unsigned-byte 29) from start below end by 64
	       until (< (- end offset) 64)
	       do
	       (fill-block-char block sequence offset)
	       (update-md5-block regs block)
	       finally
	       (let ((amount (- end offset)))
		 (unless (zerop amount)
		   (copy-to-buffer sequence offset amount buffer 0))
		 (setf (md5-state-buffer-index state) amount))))))
    (setf (md5-state-amount state)
	  #-md5-small-length (+ (md5-state-amount state) length)
	  #+md5-small-length (the (unsigned-byte 29)
			       (+ (md5-state-amount state) length)))
    state))

(defun finalize-md5-state (state)
  "If the given md5-state has not already been finalized, finalize it,
by processing any remaining input in its buffer, with suitable padding
and appended bit-length, as specified by the MD5 standard.

The resulting MD5 message-digest is returned as an array of sixteen
(unsigned-byte 8) values.  Calling `update-md5-state' after a call to
`finalize-md5-state' results in unspecified behaviour."
  (declare (type md5-state state)
	   (optimize (speed 3) #+(or cmu sbcl) (safety 0) (space 0) (debug 0))
	   #+cmu
	   (ext:optimize-interface (safety 1) (debug 1)))
  (or (md5-state-finalized-p state)
      (let ((regs (md5-state-regs state))
	    (block (md5-state-block state))
	    (buffer (md5-state-buffer state))
	    (buffer-index (md5-state-buffer-index state))
	    (total-length (* 8 (md5-state-amount state))))
	(declare (type md5-regs regs)
		 (type (integer 0 63) buffer-index)
		 (type (simple-array ub32 (16)) block)
		 (type (simple-array (unsigned-byte 8) (*)) buffer))
	;; Add mandatory bit 1 padding
	(setf (aref buffer buffer-index) #x80)
	;; Fill with 0 bit padding
	(loop for index of-type (integer 0 64)
	      from (1+ buffer-index) below 64
	      do (setf (aref buffer index) #x00))
	(fill-block-ub8 block buffer 0)
	;; Flush block first if length wouldn't fit
	(when (>= buffer-index 56)
	  (update-md5-block regs block)
	  ;; Create new fully 0 padded block
	  (loop for index of-type (integer 0 16) from 0 below 16
		do (setf (aref block index) #x00000000)))
	;; Add 64bit message bit length
	(setf (aref block 14) (ldb (byte 32 0) total-length))
	#-md5-small-length
	(setf (aref block 15) (ldb (byte 32 32) total-length))
	;; Flush last block
	(update-md5-block regs block)
	;; Done, remember digest for later calls
	(setf (md5-state-finalized-p state)
	      (md5regs-digest regs)))))

;;; High-Level Drivers

(defun md5sum-sequence (sequence &key (start 0) end)
  "Calculate the MD5 message-digest of data in sequence.  On CMU CL
this works for all sequences whose element-type is supported by the
underlying MD5 routines, on other implementations it only works for 1d
simple-arrays with such element types."
  (declare (optimize (speed 3) (space 0) (debug 0))
	   (type vector sequence) (type fixnum start))
  (let ((state (make-md5-state)))
    (declare (type md5-state state))
    #+cmu
    (lisp::with-array-data ((data sequence) (real-start start) (real-end end))
      (update-md5-state state data :start real-start :end real-end))
    #+sbcl
    (sb-kernel:with-array-data ((data sequence) (real-start start) (real-end end))
      (update-md5-state state data :start real-start :end real-end))
    #-(or cmu sbcl)
    (let ((real-end (or end (length sequence))))
      (declare (type fixnum real-end))
      (update-md5-state state sequence :start start :end real-end))
    (finalize-md5-state state)))

(defconstant +buffer-size+ (* 128 1024)
  "Size of internal buffer to use for md5sum-stream and md5sum-file
operations.  This should be a multiple of 64, the MD5 block size.")

(deftype buffer-index () `(integer 0 ,+buffer-size+))

(defun md5sum-stream (stream)
  "Calculate an MD5 message-digest of the contents of stream.  Its
element-type has to be either (unsigned-byte 8) or character."
  (declare (optimize (speed 3) (space 0) (debug 0)))
  (let ((state (make-md5-state)))
    (declare (type md5-state state))
    (cond
      ((equal (stream-element-type stream) '(unsigned-byte 8))
       (let ((buffer (make-array +buffer-size+
				 :element-type '(unsigned-byte 8))))
	 (declare (type (simple-array (unsigned-byte 8) (#.+buffer-size+))
			buffer))
	 (loop for bytes of-type buffer-index = (read-sequence buffer stream)
	       do (update-md5-state state buffer :end bytes)
	       until (< bytes +buffer-size+)
	       finally
	       (return (finalize-md5-state state)))))
      ((equal (stream-element-type stream) 'character)
       (let ((buffer (make-string +buffer-size+)))
	 (declare (type (simple-string #.+buffer-size+) buffer))
	 (loop for bytes of-type buffer-index = (read-sequence buffer stream)
	       do (update-md5-state state buffer :end bytes)
	       until (< bytes +buffer-size+)
	       finally
	       (return (finalize-md5-state state)))))
      (t
       (error "Unsupported stream element-type ~S for stream ~S."
	      (stream-element-type stream) stream)))))

(defun md5sum-file (pathname)
  "Calculate the MD5 message-digest of the file specified by pathname."
  (declare (optimize (speed 3) (space 0) (debug 0)))
  (with-open-file (stream pathname :element-type '(unsigned-byte 8))
    (md5sum-stream stream)))

#+cmu
(eval-when (:compile-toplevel :execute)
  (setq *features* *old-features*))

#+cmu
(eval-when (:compile-toplevel)
  (setq ext:*inline-expansion-limit* *old-expansion-limit*))

#+sbcl
(eval-when (:compile-toplevel)
  (setq *features* *old-features*))