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(in-package #:org.shirakumo.zippy)
(defvar *structures* (make-hash-table :test 'eql))
(defun decode-structure (vector index)
(let* ((signature (nibbles:ub32ref/le vector index))
(parser (or (gethash signature *structures*)
(error 'unknown-block-signature :signature signature))))
(funcall (first parser) vector (+ index 4))))
(defun read-structure (stream)
(let* ((signature (nibbles:read-ub32/le stream))
(parser (or (gethash signature *structures*)
(error 'unknown-block-signature :signature signature))))
(funcall (second parser) stream)))
(defun encode-structure (structure vector index)
(let ((parser (or (gethash (type-of structure) *structures*)
(error 'unknown-structure-type :object structure))))
(funcall (third parser) structure vector index)))
(defun write-structure (structure stream)
(let ((parser (or (gethash (type-of structure) *structures*)
(error 'unknown-structure-type :object structure))))
(funcall (fourth parser) structure stream)))
(defun integer-binary-type (integer)
(cond ((<= integer #xFF) 'ub8)
((<= integer #xFFFF) 'ub16)
((<= integer #xFFFFFFFF) 'ub32)
((<= integer #xFFFFFFFFFFFFFFFF) 'ub64)
(T (error 'integer-too-large))))
(defun binary-type-size (type)
(ecase type
(ub8 1)
(ub16 2)
(ub32 4)
(ub64 8)))
(defun binary-type-type (type)
(ecase type
(ub8 '(unsigned-byte 8))
(ub16 '(unsigned-byte 16))
(ub32 '(unsigned-byte 32))
(ub64 '(unsigned-byte 64))))
(defun binary-type-decoder (type)
(ecase type
(ub8 'aref)
(ub16 'nibbles:ub16ref/le)
(ub32 'nibbles:ub32ref/le)
(ub64 'nibbles:ub64ref/le)))
(defun binary-type-reader (type)
(ecase type
(ub8 'read-byte)
(ub16 'nibbles:read-ub16/le)
(ub32 'nibbles:read-ub32/le)
(ub64 'nibbles:read-ub64/le)))
(defun binary-type-encoder (type)
(ecase type
(ub8 '(lambda (vector index value)
(setf (aref vector index) value)))
(ub16 '(lambda (vector index value)
(setf (nibbles::ub16ref/le vector index) value)))
(ub32 '(lambda (vector index value)
(setf (nibbles::ub32ref/le vector index) value)))
(ub64 '(lambda (vector index value)
(setf (nibbles::ub64ref/le vector index) value)))))
(defun binary-type-writer (type)
(ecase type
(ub8 'write-byte)
(ub16 'nibbles:write-ub16/le)
(ub32 'nibbles:write-ub32/le)
(ub64 'nibbles:write-ub64/le)))
(defun generate-record-decoder (record vector index)
(destructuring-bind (name type &optional count) record
(cond ((typep type 'integer)
(let ((btype (integer-binary-type type)))
`(progn
(decf size ,(binary-type-size btype))
(setf ,name (,(binary-type-decoder btype) ,vector ,index))
(incf ,index ,(binary-type-size btype))
(unless (= ,type ,name)
(error 'mismatched-type-signature :signature ,name)))))
(count
`(progn
(setf ,name (make-array ,count :element-type ',(binary-type-type type)))
(decf size (* (length ,name) ,(binary-type-size type)))
(loop for i from 0 below (length ,name)
do (setf (aref ,name i) (,(binary-type-decoder type) ,vector ,index))
(incf ,index ,(binary-type-size type)))))
(T
`(progn
(decf size ,(binary-type-size type))
(setf ,name (,(binary-type-decoder type) ,vector ,index))
(incf ,index ,(binary-type-size type)))))))
(defun generate-record-reader (record stream)
(destructuring-bind (name type &optional count) record
(cond ((typep type 'integer)
(let ((btype (integer-binary-type type)))
`(progn
(setf ,name (,(binary-type-reader btype) ,stream))
(unless (= ,type ,name)
(error 'mismatched-type-signature :signature ,name)))))
(count
`(progn
(setf ,name (make-array ,count :element-type ',(binary-type-type type)))
(loop for i from 0 below (length ,name)
do (setf (aref ,name i) (,(binary-type-reader type) ,stream)))))
(T
`(setf ,name (,(binary-type-reader type) ,stream))))))
(defun generate-record-encoder (record vector index)
(destructuring-bind (name type &optional count) record
(cond ((typep type 'integer)
(let ((btype (integer-binary-type type)))
`(progn (,(binary-type-encoder btype) ,vector ,index ,type)
(incf ,index ,(binary-type-size btype)))))
(count
(if (eql type 'character)
`(let ((vec (babel:string-to-octets ,name :encoding :utf-8)))
(loop for char across vec
do (setf (aref ,vector ,index) char)
(incf ,index)
finally (return ,index)))
`(loop for i from 0 below ,count
do (,(binary-type-encoder type) ,vector ,index (aref ,name i))
(incf ,index ,(binary-type-size type))
finally (return ,index))))
(T
`(progn (,(binary-type-encoder type) ,vector ,index ,name)
(incf ,index ,(binary-type-size type)))))))
(defun generate-record-writer (record stream)
(destructuring-bind (name type &optional count) record
(cond ((typep type 'integer)
(let ((btype (integer-binary-type type)))
`(,(binary-type-writer btype) ,type ,stream)))
(count
(if (eql type 'character)
`(let ((vec (babel:string-to-octets ,name :encoding :utf-8)))
(loop for char across vec
do (write-byte char ,stream)))
`(loop for i from 0 below ,count
do (,(binary-type-writer type) (aref ,name i) ,stream))))
(T
`(,(binary-type-writer type) ,name ,stream)))))
(defmacro define-byte-structure (name &body records)
(destructuring-bind (name signature) (if (listp name) name (list name NIL))
(let ((fields (mapcar #'first records))
(constructor (intern (format NIL "~a-~a" 'make name)))
(decode-name (intern (format NIL "~a-~a" 'decode name)))
(read-name (intern (format NIL "~a-~a" 'read name)))
(encode-name (intern (format NIL "~a-~a" 'encode name)))
(write-name (intern (format NIL "~a-~a" 'write name))))
`(progn
(defstruct (,name (:constructor ,constructor ,fields))
,@fields)
(defun ,decode-name (vector index &optional (size most-positive-fixnum))
(let ,(remove 'size fields)
(block NIL
,@(loop for record in records
collect `(when (<= size 0) (return))
collect (generate-record-decoder record 'vector 'index)))
(values (,constructor ,@fields) index)))
(defun ,read-name (stream)
(let ,fields
,@(loop for record in records
collect (generate-record-reader record 'stream))
(,constructor ,@fields)))
(defun ,encode-name (structure vector index)
,@(typecase signature
((unsigned-byte 16)
`((setf (nibbles:ub16ref/le vector index) ,signature)
(incf index 2)))
((unsigned-byte 32)
`((setf (nibbles:ub32ref/le vector index) ,signature)
(incf index 4))))
(with-slots ,fields structure
,@(loop for record in records
collect (generate-record-encoder record 'vector 'index))))
(defun ,write-name (structure stream)
,@(typecase signature
((unsigned-byte 16)
`((nibbles:write-ub16/le ,signature stream)))
((unsigned-byte 32)
`((nibbles:write-ub32/le ,signature stream))))
(with-slots ,fields structure
,@(loop for record in records
collect (generate-record-writer record 'stream))))
,@(when signature
`((setf (gethash ',name *structures*)
(setf (gethash ,signature *structures*)
(list #',decode-name #',read-name #',encode-name #',write-name)))))))))
(defun decode-string (octets flags)
(babel:octets-to-string octets :encoding (if (logbitp 11 flags) :utf-8 :cp437)))
(defun encode-string (string)
(if string
(babel:string-to-octets string :encoding :utf-8)
#()))
(defun decode-msdos-timestamp (date time)
(let ((yy (ldb (byte 7 9) date))
(mm (ldb (byte 4 5) date))
(dd (ldb (byte 5 0) date))
(h (ldb (byte 5 11) time))
(m (ldb (byte 6 5) time))
(s (ldb (byte 5 0) time)))
(flet ((clamp (l x h)
(min h (max l x))))
(encode-universal-time (clamp 0 (1+ (* 2 s)) 59) (clamp 0 (1- m) 59) (clamp 0 (1- h) 23) (clamp 1 dd 31) (clamp 1 mm 12) (+ 1980 yy) NIL))))
(defun encode-msdos-timestamp (timestamp)
(multiple-value-bind (s m h dd mm yy) (decode-universal-time timestamp NIL)
(let ((date 0)
(time 0))
(setf (ldb (byte 7 9) date) (- yy 1980))
(setf (ldb (byte 4 5) date) mm)
(setf (ldb (byte 5 0) date) dd)
(setf (ldb (byte 5 11) time) (1+ h))
(setf (ldb (byte 6 5) time) (1+ m))
(setf (ldb (byte 5 0) time) (floor s 2))
(values date time))))
(defun decode-version (version)
(multiple-value-bind (major minor) (floor (ldb (byte 8 0) version) 10)
(list major minor)))
(defun encode-version (version &optional compatibility)
(check-type version (cons (integer 0 9) (cons (integer 0 9) null)))
(let ((idx (etypecase compatibility
(null 0)
(integer compatibility)
(keyword (file-attribute-id compatibility))))
(int (+ (* 10 (first version)) (second version))))
(setf (ldb (byte 8 8) int) idx)
int))
(defun decode-file-attribute (compat attr)
(let ((compat (file-attribute-name compat))
(msdos (ldb (byte 8 0) attr))
(os-specific (ldb (byte 16 16) attr)))
(list (file-attributes:decode-attributes msdos :windows) compat os-specific)))
(defun encode-file-attribute (thing)
(destructuring-bind (msdos compat os-specific) thing
(declare (ignore compat))
(let ((i 0))
(setf (ldb (byte 8 0) i) (logand #xFF (file-attributes:encode-attributes msdos :windows)))
(setf (ldb (byte 16 16) i) (logand #xFFFF os-specific))
i)))
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