anchor.diff:  (defpackage "CL-YFS-EXTENT-SERVER"
     (:use :common-lisp :s-xml-rpc :sb-thread)
     (:import-from :s-xml-rpc :start-xml-rpc-server)
  -  (:export :get_block :put_block :new_block :delete_block))
  +  (:export :get_block :put_block :new_block :free_block))
   
   (in-package :cl-yfs-extent-server)
   
  
positive.code:   "convert the block-number to the offset of file (file position)"
    (* (+ *bitmap-block-number* block-num) *block-size*))
  
  
  ;;; allocate and deallocate a block
  ;;; the allocate function will use random number
  
  (defun new_block ()
    "allocate a free block"
    nil)
  
  (defun delete_block (block-num)
    "deallocate a block. T on success, nil on error"
    nil)
  
  ;;; Getting and putting data from/to a block with given block number
  
  
negative.code: (defparameter *bitmap-block-number* 2)
  
  (defparameter *file-stream* nil)
  
  (defun max-block-num ()
    "Get the max number of blocks"
    (* *bitmap-block-number* *block-size* 8))
  
  
  ;;; file stream open/close wrapper
  