--- /dev/null
+;;;; This file implements the Base64 transfer encoding algorithm as
+;;;; defined in RFC 1521 by Borensten & Freed, September 1993.
+;;;; See: http://www.ietf.org/rfc/rfc1521.txt
+;;;;
+;;;; Based on initial public domain code by Juri Pakaste <juri@iki.fi>
+;;;;
+;;;; Extended by Kevin M. Rosenberg <kevin@rosenberg.net>:
+;;;; - .asd file
+;;;; - numerous speed optimizations
+;;;; - conversion to and from integers
+;;;; - Renamed functions now that supporting integer conversions
+;;;; - URI-compatible encoding using :uri key
+;;;;
+;;;; Copyright 2002-2003 Kevin M. Rosenberg
+;;;; Permission to use with BSD-style license included in the COPYING file
+;;;;
+;;;; $Id: src.lisp,v 1.1 2002/12/29 06:14:49 kevin Exp $
+
+(defpackage #:base64
+ (:use #:cl)
+ (:export #:base64-to-string #:base64-to-integer
+ #:string-to-base64 #:integer-to-base64))
+
+(in-package #:base64)
+
+(eval-when (:compile-toplevel :load-toplevel :execute)
+ (defvar *encode-table*
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
+ (declaim (type simple-string *encode-table*))
+
+ (defvar *uri-encode-table*
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_")
+ (declaim (type simple-string *uri-encode-table*))
+
+ (deftype decode-table () '(simple-array fixnum (256)))
+
+ (defvar *decode-table*
+ (let ((da (make-array 256 :adjustable nil :fill-pointer nil
+ :element-type 'fixnum
+ :initial-element -1)))
+ (loop for char of-type character across *encode-table*
+ for index of-type fixnum from 0 below 64
+ do (setf (aref da (the fixnum (char-code char))) index))
+ da))
+
+ (defvar *uri-decode-table*
+ (let ((da (make-array 256 :adjustable nil :fill-pointer nil
+ :element-type 'fixnum
+ :initial-element -1)))
+ (loop
+ for char of-type character across *uri-encode-table*
+ for index of-type fixnum from 0 below 64
+ do (setf (aref da (the fixnum (char-code char))) index))
+ da))
+
+ (declaim (type decode-table *decode-table* *uri-decode-table*))
+
+ (defvar *pad-char* #\=)
+ (defvar *uri-pad-char* #\.)
+ (declaim (type character *pad-char* *uri-pad-char*))
+ )
+
+(defun string-to-base64 (string &key (uri nil))
+ "Encode a string array to base64."
+ (declare (string string)
+ (optimize (speed 3)))
+ (let ((pad (if uri *uri-pad-char* *pad-char*))
+ (encode-table (if uri *uri-encode-table* *encode-table*)))
+ (declare (simple-string encode-table)
+ (character pad))
+ (let* ((string-length (length string))
+ (result (make-string
+ (* 4 (truncate (/ (+ 2 string-length) 3))))))
+ (declare (fixnum string-length)
+ (simple-string result))
+ (do ((sidx 0 (the fixnum (+ sidx 3)))
+ (didx 0 (the fixnum (+ didx 4)))
+ (chars 2 2)
+ (value 0 0))
+ ((>= sidx string-length) t)
+ (declare (fixnum sidx didx chars value))
+ (setf value (ash (logand #xFF (char-code (char string sidx))) 8))
+ (dotimes (n 2)
+ (declare (fixnum n))
+ (when (< (the fixnum (+ sidx n 1)) string-length)
+ (setf value
+ (logior value
+ (the fixnum
+ (logand #xFF
+ (the fixnum
+ (char-code (char string
+ (the fixnum
+ (+ sidx n 1)))))))))
+ (incf chars))
+ (when (zerop n)
+ (setf value (the fixnum (ash value 8)))))
+ (setf (schar result (the fixnum (+ didx 3)))
+ (if (> chars 3)
+ (schar encode-table (logand value #x3F))
+ pad))
+ (setf value (the fixnum (ash value -6)))
+ (setf (schar result (the fixnum (+ didx 2)))
+ (if (> chars 2)
+ (schar encode-table (logand value #x3F))
+ pad))
+ (setf value (the fixnum (ash value -6)))
+ (setf (schar result (the fixnum (1+ didx)))
+ (schar encode-table (logand value #x3F)))
+ (setf value (the fixnum (ash value -6)))
+ (setf (schar result didx)
+ (schar encode-table (logand value #x3F))))
+ result)))
+
+
+(defun round-next-multiple (x n)
+ "Round x up to the next highest multiple of n"
+ (declare (fixnum n)
+ (optimize (speed 3)))
+ (let ((remainder (mod x n)))
+ (declare (fixnum remainder))
+ (if (zerop remainder)
+ x
+ (the fixnum (+ x (the fixnum (- n remainder)))))))
+
+(defun integer-to-base64 (input &key (uri nil))
+ "Encode an integer to base64 format."
+ (declare (integer input)
+ (optimize (speed 3)))
+ (let ((pad (if uri *uri-pad-char* *pad-char*))
+ (encode-table (if uri *uri-encode-table* *encode-table*)))
+ (declare (simple-string encode-table)
+ (character pad))
+ (do* ((input-bits (integer-length input))
+ (byte-bits (round-next-multiple input-bits 8))
+ (padded-bits (round-next-multiple byte-bits 6))
+ (remainder-padding (mod padded-bits 24))
+ (padding-bits (if (zerop remainder-padding)
+ 0
+ (- 24 remainder-padding)))
+ (strlen (/ (+ padded-bits padding-bits) 6))
+ (padding-chars (/ padding-bits 6))
+ (nonpad-chars (- strlen padding-chars))
+ (last-nonpad-char (1- nonpad-chars))
+ (str (make-string strlen))
+ (strpos 0 (1+ strpos))
+ (int (ash input (/ padding-bits 3)) (ash int -6))
+ (6bit-value (logand int #x3f) (logand int #x3f)))
+ ((= strpos nonpad-chars)
+ (dotimes (ipad padding-chars)
+ (setf (schar str strpos) pad)
+ (incf strpos))
+ str)
+ (declare (fixnum 6bit-value strpos strlen last-nonpad-char)
+ (integer int))
+ (setf (schar str (the fixnum (- last-nonpad-char strpos)))
+ (schar encode-table 6bit-value)))))
+
+;;; Decoding
+
+(defun base64-to-string (string &key (uri nil))
+ "Decode a base64 string to a string array."
+ (declare (string string)
+ (optimize (speed 3)))
+ (let ((pad (if uri *uri-pad-char* *pad-char*))
+ (decode-table (if uri *uri-decode-table* *decode-table*)))
+ (declare (type decode-table decode-table)
+ (character pad))
+ (let ((result (make-string (* 3 (truncate (/ (length string) 4)))))
+ (ridx 0))
+ (declare (simple-string result)
+ (fixnum ridx))
+ (loop
+ for char of-type character across string
+ for svalue of-type fixnum = (aref decode-table (the fixnum (char-code char)))
+ with bitstore of-type fixnum = 0
+ with bitcount of-type fixnum = 0
+ do
+ (cond
+ ((char= char pad)
+ ;; Could add checks to make sure padding is correct
+ ;; Currently, padding is ignored
+ )
+ ((minusp svalue)
+ (warn "Bad character ~W in base64 decode" char))
+ (t
+ (setf bitstore (logior
+ (the fixnum (ash bitstore 6))
+ svalue))
+ (incf bitcount 6)
+ (when (>= bitcount 8)
+ (decf bitcount 8)
+ (setf (char result ridx)
+ (code-char (the fixnum
+ (logand
+ (the fixnum
+ (ash bitstore
+ (the fixnum (- bitcount))))
+ #xFF))))
+ (incf ridx)
+ (setf bitstore (the fixnum (logand bitstore #xFF)))))))
+ (subseq result 0 ridx))))
+
+
+(defun base64-to-integer (string &key (uri nil))
+ "Decodes a base64 string to an integer"
+ (declare (string string)
+ (optimize (speed 3)))
+ (let ((pad (if uri *uri-pad-char* *pad-char*))
+ (decode-table (if uri *uri-decode-table* *decode-table*)))
+ (declare (type decode-table decode-table)
+ (character pad))
+ (let ((value 0))
+ (declare (integer value))
+ (loop
+ for char of-type character across string
+ for svalue of-type fixnum =
+ (aref decode-table (the fixnum (char-code char)))
+ do
+ (cond
+ ((char= char pad)
+ (setq value (the fixnum (ash value -2))))
+ ((minusp svalue)
+ (warn "Bad character ~W in base64 decode" char))
+ (t
+ (setq value (the fixnum
+ (+ svalue (the fixnum (ash value 6))))))))
+ value)))
projects / cl-base64.git / blobdiff