checksum.lisp

   1 ;;;
   2 ;;; Copyright (c) 2007 Zachary Beane, All Rights Reserved
   3 ;;;
   4 ;;; Redistribution and use in source and binary forms, with or without
   5 ;;; modification, are permitted provided that the following conditions
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   9 ;;;     notice, this list of conditions and the following disclaimer.
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  11 ;;;   * Redistributions in binary form must reproduce the above
  12 ;;;     copyright notice, this list of conditions and the following
  13 ;;;     disclaimer in the documentation and/or other materials
  14 ;;;     provided with the distribution.
  15 ;;;
  16 ;;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS' AND ANY EXPRESSED
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  28
  29 (in-package #:salza2)
  30
  31 (defclass checksum () ())
  32
  33 (defgeneric update (checksum buffer start count)
  34   (:documentation "Update the CHECKSUM object with COUNT octets
  35   from BUFFER, starting from START."))
  36
  37 (defgeneric result (checksum)
  38   (:documentation "Return the result of CHECKSUM as an integer."))
  39
  40 (defgeneric result-octets (checksum)
  41   (:documentation "Return the result of CHECKSUM as a list of
  42   octets, in MSB order."))
  43
  44 (defun ub32-octets (result)
  45   (list (ldb (byte 8 24) result)
  46         (ldb (byte 8 16) result)
  47         (ldb (byte 8  8) result)
  48         (ldb (byte 8  0) result)))