1 ;;;; This file implements the Base64 transfer encoding algorithm as
2 ;;;; defined in RFC 1521 by Borensten & Freed, September 1993.
3 ;;;; See: http://www.ietf.org/rfc/rfc1521.txt
5 ;;;; Based on initial public domain code by Juri Pakaste <juri@iki.fi>
7 ;;;; Extended by Kevin M. Rosenberg <kevin@rosenberg.net>:
9 ;;;; - numerous speed optimizations
10 ;;;; - conversion to and from integers
11 ;;;; - Renamed functions now that supporting integer conversions
12 ;;;; - URI-compatible encoding using :uri key
14 ;;;; Copyright 2002-2003 Kevin M. Rosenberg
15 ;;;; Permission to use with BSD-style license included in the COPYING file
17 ;;;; $Id: src.lisp,v 1.3 2003/01/04 06:13:53 kevin Exp $
21 (:export #:base64-to-string #:base64-to-integer
22 #:string-to-base64 #:integer-to-base64))
27 (eval-when (:compile-toplevel :load-toplevel :execute)
28 (defvar *encode-table*
29 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
30 (declaim (type simple-string *encode-table*))
32 (defvar *uri-encode-table*
33 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_")
34 (declaim (type simple-string *uri-encode-table*))
36 (deftype decode-table () '(simple-array fixnum (256)))
38 (defvar *decode-table*
39 (let ((da (make-array 256 :adjustable nil :fill-pointer nil
41 :initial-element -1)))
42 (loop for char of-type character across *encode-table*
43 for index of-type fixnum from 0 below 64
44 do (setf (aref da (the fixnum (char-code char))) index))
47 (defvar *uri-decode-table*
48 (let ((da (make-array 256 :adjustable nil :fill-pointer nil
50 :initial-element -1)))
52 for char of-type character across *uri-encode-table*
53 for index of-type fixnum from 0 below 64
54 do (setf (aref da (the fixnum (char-code char))) index))
57 (declaim (type decode-table *decode-table* *uri-decode-table*))
59 (defvar *pad-char* #\=)
60 (defvar *uri-pad-char* #\.)
61 (declaim (type character *pad-char* *uri-pad-char*))
67 (defun round-next-multiple (x n)
68 "Round x up to the next highest multiple of n."
71 (let ((remainder (mod x n)))
72 (declare (fixnum remainder))
75 (the fixnum (+ x (the fixnum (- n remainder)))))))
77 (declaim (inline whitespace-p))
78 (defun whitespace-p (c)
79 "Returns T for a whitespace character."
80 (or (char= c #\Newline) (char= c #\Linefeed)
81 (char= c #\Return) (char= c #\Space)
87 (defun string-to-base64 (string &key (uri nil) (columns 0) (stream nil))
88 "Encode a string array to base64. If columns is > 0, designates
89 maximum number of columns in a line and the string will be terminated
91 (declare (string string)
94 (let ((pad (if uri *uri-pad-char* *pad-char*))
95 (encode-table (if uri *uri-encode-table* *encode-table*)))
96 (declare (simple-string encode-table)
98 (let* ((string-length (length string))
99 (complete-group-count (truncate string-length 3))
100 (remainder (nth-value 1 (truncate string-length 3)))
101 (padded-length (+ remainder
102 (* 4 complete-group-count)))
103 (num-lines (if (plusp columns)
104 (truncate (+ padded-length (1- columns)) columns)
106 (num-breaks (if (plusp num-lines)
109 (strlen (+ padded-length num-breaks))
110 (result (unless stream
111 (make-string strlen)))
112 (col (if (plusp columns)
116 (declare (fixnum string-length padded-length col ioutput)
117 (simple-string result))
118 (labels ((output-char (ch)
119 (when (= col columns)
121 (write #\Newline stream)
123 (setf (schar result ioutput) #\Newline)
130 (setf (schar result ioutput) ch)
132 (output-group (svalue chars)
137 (the fixnum (ash svalue -18))))))
142 (the fixnum (ash svalue -12))))))
148 (the fixnum (ash svalue -6))))))
154 (logand #x3f svalue))))
156 (do ((igroup 0 (1+ igroup))
157 (isource 0 (+ isource 3))
159 ((= igroup complete-group-count)
166 (ash (char-code (the character
167 (char string isource))) 16))
169 (ash (char-code (the character
170 (char string (1+ isource)))) 8)))))
171 (output-group svalue 3))
175 (char-code (the character
176 (char string isource)))))
177 (output-group svalue 2)))
179 (declare (fixnum igroup isource svalue))
184 (ash (char-code (the character
185 (char string isource))) 16))
187 (ash (char-code (the character
188 (char string (1+ isource)))) 8))
190 (char-code (the character
191 (char string (+ 2 isource))))))))
192 (output-group svalue 4))))))
195 (defun integer-to-base64 (input &key (uri nil) (columns 0) (stream nil))
197 (integer-to-base64-stream input stream :uri uri :columns columns)
198 (integer-to-base64-string input :uri uri :columns columns)))
200 (defun integer-to-base64-string (input &key (uri nil) (columns 0))
201 "Encode an integer to base64 format."
202 (declare (integer input)
204 (optimize (speed 3)))
205 (let ((pad (if uri *uri-pad-char* *pad-char*))
206 (encode-table (if uri *uri-encode-table* *encode-table*)))
207 (declare (simple-string encode-table)
209 (let* ((input-bits (integer-length input))
210 (byte-bits (round-next-multiple input-bits 8))
211 (padded-bits (round-next-multiple byte-bits 6))
212 (remainder-padding (mod padded-bits 24))
213 (padding-bits (if (zerop remainder-padding)
215 (- 24 remainder-padding)))
216 (padding-chars (/ padding-bits 6))
217 (padded-length (/ (+ padded-bits padding-bits) 6))
218 (last-line-len (if (plusp columns)
219 (- padded-length (* columns
221 padded-length columns)))
223 (num-lines (if (plusp columns)
224 (truncate (+ padded-length (1- columns)) columns)
226 (num-breaks (if (plusp num-lines)
229 (strlen (+ padded-length num-breaks))
230 (last-char (1- strlen))
231 (str (make-string strlen))
232 (col (if (zerop last-line-len)
234 (1- last-line-len))))
235 (declare (fixnum padded-length num-lines col last-char
236 padding-chars last-line-len))
237 (unless (plusp columns)
238 (setq col -1)) ;; set to flag to optimize in loop
240 (dotimes (i padding-chars)
242 (setf (schar str (the fixnum (- last-char i))) pad))
244 (do* ((strpos (- last-char padding-chars) (1- strpos))
245 (int (ash input (/ padding-bits 3))))
248 (declare (fixnum strpos) (integer int))
251 (setf (schar str strpos) #\Newline)
254 (setf (schar str strpos)
255 (schar encode-table (the fixnum (logand int #x3f))))
256 (setq int (ash int -6))
259 (defun integer-to-base64-stream (input stream &key (uri nil) (columns 0))
260 "Encode an integer to base64 format."
261 (declare (integer input)
263 (optimize (speed 3)))
264 (let ((pad (if uri *uri-pad-char* *pad-char*))
265 (encode-table (if uri *uri-encode-table* *encode-table*)))
266 (declare (simple-string encode-table)
268 (let* ((input-bits (integer-length input))
269 (byte-bits (round-next-multiple input-bits 8))
270 (padded-bits (round-next-multiple byte-bits 6))
271 (remainder-padding (mod padded-bits 24))
272 (padding-bits (if (zerop remainder-padding)
274 (- 24 remainder-padding)))
275 (padding-chars (/ padding-bits 6))
276 (padded-length (/ (+ padded-bits padding-bits) 6))
277 (strlen padded-length)
278 (nonpad-chars (- strlen padding-chars))
279 (last-nonpad-char (1- nonpad-chars))
280 (str (make-string strlen)))
281 (declare (fixnum padded-length last-nonpad-char))
282 (do* ((strpos 0 (1+ strpos))
283 (int (ash input (/ padding-bits 3)) (ash int -6))
284 (6bit-value (logand int #x3f) (logand int #x3f)))
285 ((= strpos nonpad-chars)
287 (declare (fixnum col))
288 (dotimes (i nonpad-chars)
290 (write-char (schar str i) stream)
291 (when (plusp columns)
293 (when (= col columns)
294 (write-char #\Newline stream)
296 (dotimes (ipad padding-chars)
297 (declare (fixnum ipad))
298 (write-char pad stream)
299 (when (plusp columns)
301 (when (= col columns)
302 (write-char #\Newline stream)
305 (declare (fixnum 6bit-value strpos)
307 (setf (schar str (- last-nonpad-char strpos))
308 (schar encode-table 6bit-value))
313 (defun base64-to-string (string &key (uri nil))
314 "Decode a base64 string to a string array."
315 (declare (string string)
316 (optimize (speed 3)))
317 (let ((pad (if uri *uri-pad-char* *pad-char*))
318 (decode-table (if uri *uri-decode-table* *decode-table*)))
319 (declare (type decode-table decode-table)
321 (let ((result (make-string (* 3 (truncate (length string) 4))))
323 (declare (simple-string result)
326 for char of-type character across string
327 for svalue of-type fixnum = (aref decode-table (the fixnum (char-code char)))
328 with bitstore of-type fixnum = 0
329 with bitcount of-type fixnum = 0
333 (setf bitstore (logior
334 (the fixnum (ash bitstore 6))
337 (when (>= bitcount 8)
339 (setf (char result ridx)
340 (code-char (the fixnum
344 (the fixnum (- bitcount))))
347 (setf bitstore (the fixnum (logand bitstore #xFF)))))
349 ;; Could add checks to make sure padding is correct
350 ;; Currently, padding is ignored
356 (warn "Bad character ~W in base64 decode" char))
358 (subseq result 0 ridx))))
361 (defun base64-to-integer (string &key (uri nil))
362 "Decodes a base64 string to an integer"
363 (declare (string string)
364 (optimize (speed 3)))
365 (let ((pad (if uri *uri-pad-char* *pad-char*))
366 (decode-table (if uri *uri-decode-table* *decode-table*)))
367 (declare (type decode-table decode-table)
370 (declare (integer value))
372 for char of-type character across string
373 for svalue of-type fixnum =
374 (aref decode-table (the fixnum (char-code char)))
378 (setq value (+ svalue (ash value 6))))
380 (setq value (ash value -2)))
385 (warn "Bad character ~W in base64 decode" char))))