lodematron-binary.lisp

   1
   2 (in-package :lodematron)
   3
   4
   5 ;; buffering binary files --------------------
   6
   7 ;; read and write an entire file to memory in one go
   8 (defun read-file-to-usb8-array (filepath)
   9   "Opens a reads a file. Returns the contents as single unsigned-byte array"
  10   (with-open-file (in filepath :direction :input :element-type '(unsigned-byte 8))
  11     (let* ((file-len (file-length in))
  12            (usb8 (make-array file-len :element-type '(unsigned-byte 8)))
  13            (pos (read-sequence usb8 in)))
  14       (unless (= file-len pos)
  15         (error "Length read (~D) doesn't match file length (~D)~%" pos file-len))
  16       usb8)))
  17
  18 (defun write-usb8-array-to-file (usb8 file)
  19   "Opens a reads a file. Returns the contents as single unsigned-byte array"
  20   (with-open-file (out file :direction :output
  21                        :if-exists :supersede
  22                        :if-does-not-exist :create
  23                        :element-type '(unsigned-byte 8))
  24     (let* ((pos (length (write-sequence usb8 out)))
  25            (file-len (file-length out)))
  26       (unless (= file-len pos)
  27         (error "Length written (~D) doesn't match file length (~D)~%" pos file-len))
  28       usb8)))
  29
  30 ;; class to hold file data in memory
  31 (defclass binary-file-data ()
  32   ((buffered-data :accessor buffered-data-of)
  33    (buffer-pos :accessor buffer-pos-of :initform 0))
  34   ( :documentation "Binary file held in memory with accompanying seek position"))
  35
  36 ;; initalise buffer via reading a file
  37 (defmethod initialize-instance :after ((self binary-file-data) &key filepath)
  38   "Initalise a buffered via reading the lot into memory."
  39   (when filepath (setf (buffered-data-of self)
  40                        (read-file-to-usb8-array filepath))))
  41
  42 ;; writing entire files
  43 (defgeneric     write-binary-file (binary-file-data file)
  44   (:documentation "Write the buffered data to the binary file"))
  45
  46 (defmethod  write-binary-file ((self binary-file-data) file)
  47   "Write the buffered data to the binary file"
  48   (write-usb8-array-to-file
  49    (buffered-data-of self)
  50    file))
  51