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(in-package #:lempel)
(declaim (optimize (debug 3) (safety 3)))
(declaim (ftype (function ((array (unsigned-byte 8)) (unsigned-byte 8)) (array (unsigned-byte 1))) prefix-decode))
(defun prefix-decode (data prefix)
(let ((bits (make-array (* 8 (length data)) :element-type '(unsigned-byte 1)))
(result (queue:new))
(point-count 0))
(dotimes (i (length data))
(byte->bits (elt data i) bits (* 8 i)))
(do ((i 0)) ((>= i (length bits)) nil)
(cond ((and (<= i (- (length bits) 8))
(= (bits->byte bits i) prefix))
(incf point-count)
(let ((point (byte-pair->point (bits->byte bits (+ i 8))
(bits->byte bits (+ i 16)))))
(if (= (point-size point) 0)
(progn
(let ((prefix-bits (make-array 8 :element-type '(unsigned-byte 1))))
(byte->bits prefix prefix-bits 0)
(dotimes (j 8)
(queue:push (elt prefix-bits j) result))
(incf i 16)))
(progn
(queue:push point result)
(incf i 24)))))
(t (queue:push (elt bits i) result)
(incf i))))
(format t "point count: ~a~&" point-count)
(decompress (queue:to-list result))))
(declaim (ftype (function (list) (array (unsigned-byte 1))) decompress))
(defun decompress (data)
(let ((result (make-array (get-uncompressed-size data) :element-type '(unsigned-byte 1)))
(fill-count 0))
(format t "uncompressed size: ~a~&" (length result))
(dolist (point data)
(cond ((point-p point)
(let ((start (- fill-count (point-offset point))))
(dotimes (j (point-size point))
(setf (elt result (+ fill-count j)) (elt result (+ start j))))
(incf fill-count (point-size point))))
((typep point '(unsigned-byte 1))
(setf (elt result fill-count) point)
(incf fill-count))
(t (error (format nil "cannot handle type ~a" (type-of point))))))
(assert (= fill-count (length result)))
result))
(declaim (ftype (function ((unsigned-byte 8) (unsigned-byte 8)) point) byte-pair->point))
(defun byte-pair->point (b1 b2)
(let ((offset (if reversed-byte-order b2 b1))
(size (if reversed-byte-order b1 b2))
(max-word-length (1- (ash 1 (- 16 window-bits)))))
(make-point :offset (* 8 (logior offset
(ash (logand size (logxor #xff max-word-length))
(- window-bits 8))))
:size (* 8 (logand size max-word-length)))))
(declaim (ftype (function (list) fixnum) get-uncompressed-size))
(defun get-uncompressed-size (data)
(let ((size 0))
(dolist (point data)
(cond ((point-p point)
(if (= (point-size point) 0)
(incf size 8)
(incf size (point-size point))))
(t (incf size))))
size))
(declaim (ftype (function ((array (unsigned-byte 1)) fixnum) (unsigned-byte 8)) bits->byte))
(defun bits->byte (data index)
(let ((byte 0))
(dotimes (i 8)
(setf byte (logior byte (ash (elt data (+ index i)) (- 7 i)))))
byte))
(declaim (ftype (function ((unsigned-byte 8) (array (unsigned-byte 1)) fixnum)) byte->bits))
(defun byte->bits (data bits index)
(dotimes (i 8)
(setf (elt bits (+ index i)) (ash (logand data (ash 1 (- 7 i))) (- i 7)))))
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