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;;; inflate-state.lisp -- definition of an inflate state
(in-package :chipz)
(deftype sliding-window () '(simple-array (unsigned-byte 8) (32768)))
(defstruct (inflate-state
(:include decompression-state)
(:constructor %make-inflate-state (data-format)))
;; whether the current block being processed is the last one
(final-block-p nil :type (member t nil))
;; the number of bytes to copy for uncompressed blocks
(length 0)
;; the code for length/distance codes
(distance 0)
(length-code 0 :type (integer 0 28))
(distance-code 0 :type (integer 0 31))
;; values for dynamic blocks
(n-length-codes 0)
(n-distance-codes 0)
(n-codes 0)
(n-values-read 0)
(code-lengths (make-array 288) :type (simple-vector 288))
;; sliding window
(window (make-array 32768 :element-type '(unsigned-byte 8))
:type sliding-window)
;; position in the sliding window
(window-index 0 :type (mod 32768))
;; codes table for dynamically compressed blocks
(codes-table nil)
;; literal/length table for compressed blocks
(literal/length-table *fixed-literal/length-table*
:type huffman-decode-table)
;; distance table for compressed blocks
(distance-table *fixed-distance-table* :type huffman-decode-table)
;; header for wrapped data, or NIL if raw deflate data
(header nil)
;; format of the compressed data that we're reading
(data-format 'deflate :type (member deflate zlib gzip)))
(defun make-inflate-state (format)
"Return a INFLATE-STATE structure suitable for uncompressing data in
FORMAT; FORMAT should be:
:GZIP or CHIPZ:GZIP For decompressing data in the `gzip' format;
:ZLIB or CHIPZ:ZLIB For decompressing data in the `zlib' format;
:DEFLATE or CHIPZ:DEFLATE For decompressing data in the `deflate' format.
The usual value of FORMAT will be one of CHIPZ:GZIP or CHIPZ:ZLIB."
(let* ((f (case format
((:gzip gzip) 'gzip)
((:zlib zlib) 'zlib)
((:deflate deflate) 'deflate)
(t
(error 'invalid-format-error :format format))))
(state (%make-inflate-state f)))
(case f
(gzip
(setf (dstate-checksum state) (make-crc32)
(dstate-update-checksum state) #'update-crc32))
(zlib
(setf (dstate-checksum state) (make-adler32)
(dstate-update-checksum state) #'update-adler32)))
state))
(defun finish-inflate-state (state)
(unless (inflate-state-done state)
(error 'premature-end-of-stream))
t)
(defmethod print-object ((object inflate-state) stream)
(print-unreadable-object (object stream)
(format stream "Inflate-State input ~D/~D; output ~D/~D"
(- (inflate-state-input-index object)
(inflate-state-input-start object))
(- (inflate-state-input-end object)
(inflate-state-input-index object))
(- (inflate-state-output-index object)
(inflate-state-output-start object))
(- (inflate-state-output-end object)
(inflate-state-output-index object)))))
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