#!/usr/bin/env python
# -*- coding: utf-8 -*-


"""
  To dump FAT and prepare input for this program, one can use command like this:
    # dd if=/dev/sde skip=1 count=1 | hexdump -v -e '/1 "%02X "' | tr -d ' '

  Stock FAT is this:
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
  
"""

import sys
import os

def displayCluster(cluster, hexfat):
  decfat = int(hexfat, 16)

  next = ""
  if decfat == 0:
    next = "-"
  elif decfat == 1:
    next = "invalid"
  elif decfat <= 0xfef : # 002-fef: cluster in use
    next = "next %03d" % decfat
  elif decfat <= 0xff6:  # reserved,
    next = "reserved (0x%03x)" % decfat
  elif decfat == 0xff7: #bad cluster
    next = "bad"
  elif decfat <= 0xfff: # cluster in use, the last one in this file
    next = "last in this file (0x%03x)" % decfat

  print "cluster %03d: %s" % (cluster, next)


data = sys.argv[1]

cluster = 0
while len(data) > 0:
  twofats = data[0:6]
  fat1 = twofats[3] + twofats[0:2]
  fat2 = twofats[4:6] + twofats[2]
  # print "fat1 %s, fat2 %s" % (fat1, fat2)
  data = data[len(twofats):]

  displayCluster(cluster, fat1)
  displayCluster(cluster+1, fat2)

  # print "cluster %03d: next %03d" % (cluster, int(fat1, 16))
  # print "cluster %03d: next %03d" % (cluster+1, int(fat2, 16))
  cluster = cluster + 2