/usr/share/common-lisp/source/salza2/adler32.lisp is in cl-salza2 2.0.9-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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;;; Copyright (c) 2007 Zachary Beane, All Rights Reserved
;;;
;;; Redistribution and use in source and binary forms, with or without
;;; modification, are permitted provided that the following conditions
;;; are met:
;;;
;;; * Redistributions of source code must retain the above copyright
;;; notice, this list of conditions and the following disclaimer.
;;;
;;; * Redistributions in binary form must reproduce the above
;;; copyright notice, this list of conditions and the following
;;; disclaimer in the documentation and/or other materials
;;; provided with the distribution.
;;;
;;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS' AND ANY EXPRESSED
;;; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
;;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
;;; ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
;;; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
;;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
;;; GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
;;; INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
;;; WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
;;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
;;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;;;
(in-package #:salza2)
(defconstant +adler32-base+ 65521)
(defun adler32-update (adler-high adler-low buf start count)
(declare (type array-index start count)
(type (unsigned-byte 16) adler-high adler-low)
(type octet-vector buf)
(optimize speed))
(cond ((zerop count)
(values adler-high adler-low))
(t
(let ((length count)
(i 0)
(k 0)
(s1 adler-low)
(s2 adler-high))
(declare (type (integer 0 16) k)
(type array-index i)
(type (unsigned-byte 16) length)
(type (unsigned-byte 32) s1 s2))
(tagbody
loop
(setf k (min length 16))
(decf length k)
sum
(setf s1 (+ (aref buf (logand #xFFFF (+ start i))) s1))
(setf s2 (+ s1 s2))
(decf k)
(incf i)
(unless (zerop k)
(go sum))
(setf s1 (mod s1 +adler32-base+))
(setf s2 (mod s2 +adler32-base+))
(unless (zerop length)
(go loop)))
(values s2 s1)))))
;;; Class interface
(defclass adler32-checksum (checksum)
((high
:initarg :high
:accessor high)
(low
:initarg :low
:accessor low))
(:default-initargs
:high 0
:low 1))
(defmethod result ((checksum adler32-checksum))
(+ (ash (high checksum) 16)
(low checksum)))
(defmethod result-octets ((checksum adler32-checksum))
(ub32-octets (result checksum)))
(defmethod update ((checksum adler32-checksum) buffer start count)
(setf (values (high checksum)
(low checksum))
(adler32-update (high checksum)
(low checksum)
buffer
start
count)))
(defmethod reset ((checksum adler32-checksum))
(setf (high checksum) 0
(low checksum) 1))
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