plug-ins/cgm/cgm.py

   1
   2 def read_cgm(file):
   3         if type(file) == type(''):
   4                 file = open(file, 'rb');
   5         list = []
   6         head = file.read(2);
   7         while head != '':
   8                 if len(head) != 2: break
   9                 el_class = ord(head[0]) >> 4
  10                 el_id = ((ord(head[0]) & 0x0f) << 3) | (ord(head[1]) >> 5)
  11                 el_len = ord(head[1]) & 0x1f
  12                 if el_len == 31:  # long form element
  13                         head = file.read(2)
  14                         if len(head) != 2: break
  15                         el_len = (ord(head[0]) << 8) | ord(head[1])
  16                 print (el_class, el_id, el_len)
  17
  18                 el_body = file.read(el_len)
  19                 if el_len & 1 == 1:  # odd element length
  20                         file.read(1) # discard NULL byte
  21
  22                 list.append((el_class, el_id, el_body))
  23
  24                 if (el_class, el_id) == (0, 2):
  25                         break
  26
  27                 head = file.read(2)
  28         return list