class File < IO

def fgetb
 x=0
 ret=0
 each_byte do |i|
  ret=i
  break
 end
 return ret
end

def fgetw
 x=0
 ret=0
 each_byte do |i|
  ret|=(i<<x)
  x+=8
  break if x==16
 end
 return ret
end

def fgetdw
 x=0
 ret=0
 each_byte do |i|
  ret|=(i<<x)
  x+=8
  break if x==32
 end
 return ret
end

def fgetsb
 ret=fgetb
 if (ret&0x80)!=0
  return ret-256
 else
  return ret
 end
end

def xfgetb(offset)
 self.pos=offset
 return fgetb
end

def xfgetw(offset)
 self.pos=offset
 return fgetw
end

def xfgetdw(offset)
 self.pos=offset
 return fgetdw
end

def getOffset(index)
 self.pos=0
 offset=fgetdw>>3
 return 0 if index>=offset
 self.pos=index*8
 return fgetdw
end

def getLength(index)
 self.pos=0
 offset=fgetdw>>3
 return 0 if index>=offset
 self.pos=index*8+4
 return fgetdw
end


def readName(index)
 self.pos=0
 offset=fgetdw>>3
 return "" if index>=offset
 self.pos=index*8
 offset=fgetdw
 length=fgetdw
 return "" if length==0
 self.pos=offset
 return read(length)
end

end