zlib.lisp

   1 ;;;; $Id: zlib.lisp,v 1.10 2007/12/20 16:30:09 xach Exp $
   2
   3 (in-package #:salza2)
   4
   5 (defclass zlib-compressor (deflate-compressor)
   6   ((adler32
   7     :initarg :adler32
   8     :accessor adler32))
   9   (:default-initargs
  10    :adler32 (make-instance 'adler32-checksum)))
  11
  12 (defmethod start-data-format :before ((compressor zlib-compressor))
  13   (let ((bitstream (bitstream compressor)))
  14     ;; FIXME: Replace these naked constants with symbolic constants.
  15     (write-octet 8 bitstream)
  16     (write-octet 153 bitstream)))
  17
  18 (defmethod process-input :after ((compressor zlib-compressor) input start count)
  19   (let ((checksum (adler32 compressor)))
  20     (update checksum input start count)))
  21
  22 (defmethod finish-data-format :after ((compressor zlib-compressor))
  23   (let ((bitstream (bitstream compressor)))
  24     (dolist (octet (result-octets (adler32 compressor)))
  25       (write-octet octet bitstream))))
  26