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"""
EUMEL utility functions, including:
"""
import logging
import codecs
# EUMEL character map. See “Benutzerhandbuch 1.7”, page 107.
# map eumel character to unicode codepoint
eumel2unicodemap = dict (
[(10, '\n'), (13, '\r')] +
# first part is same as ascii
[(i, chr (i)) for i in range (32, 126)] +
[(126, '~')] +
[(214, 'Ä'), (215, 'Ö'), (216, 'Ü'), (217, 'ä'), (218, 'ö'), (219, 'ü'), (220, 'k'), (221, '-'), (222, '#'), (223, ' ')] +
[(251, 'ß')])
def decode (input, errors='strict'):
ret = []
pos = 0
for pos in range (len (input)):
c = input[pos]
m = eumel2unicodemap.get (c, None)
if m:
ret.append (m)
else:
if errors == 'strict':
raise UnicodeError ('unknown char {}'.format (c))
elif errors == 'ignore':
pass
elif errors == 'replace':
ret.append ('\uFFFD')
else:
break
return (''.join (ret), pos)
def lookup (name):
if name == 'eumel':
return codecs.CodecInfo(None, decode)
return None
codecs.register (lookup)
# Dataspace utilities
import struct, os
class DataspaceTypeMismatch (ValueError):
pass
class Dataspace:
# Expected type
TYPE = None
def __init__ (self, fd):
self.fd = fd
self.lastaddr, self.firstaddr, self.type, _ = self._parseHeader ()
if self.TYPE is not None and self.type != self.TYPE:
raise DataspaceTypeMismatch ()
self.heap = {}
def _parseHeader (self):
"""
:return: (last heap address, first heap address, dataspace type, unknown)
"""
buf = self.fd.read (8)
return struct.unpack ('<HHHH', buf)
def parseText (self):
"""
Parse TEXT datatype, which can either be embedded (up to 13? chars) or in the heap (i.e. address)
"""
buf = self.fd.read (16)
address, length = struct.unpack ('<HB', buf[:3])
if length <= 13:
r = buf[3:3+length]
else:
length, = struct.unpack ('<H', buf[3:5])
r = HeapReference (self.heap, address, length)
return r
def parseInt (self, count=1):
if count == 1:
return struct.unpack ('<H', self.fd.read (1*intsize))[0]
else:
return [self.parseInt () for i in range (count)]
def parseHeap (self):
heapaddr = self.firstaddr
maxaddr = 2**(intsize*8)-1
while True:
head = self.fd.read (2)
# XXX: not sure how to find its offset
if head == b'\xff\xff':
continue
if not head or len (head) < 2:
break
length, = struct.unpack ('<H', head)
self.heap[heapaddr] = self.fd.read (length)
logging.debug ('got heap entry {:x} = ({}) {}'.format (heapaddr, length, self.heap[heapaddr]))
heapaddr = (heapaddr+2+length) % maxaddr
def skip (self, n):
self.fd.seek (n, os.SEEK_CUR)
def seek (self, pos):
self.fd.seek (pos, os.SEEK_SET)
class HeapReference:
def __init__ (self, heap, address, length):
self.heap = heap
self.address = address
self.length = length
self._item = None
def __bytes__ (self):
return self.item[:self.length]
def __len__ (self):
return self.length
def __getitem__ (self, key):
return self.item[key]
def __repr__ (self):
return '<HeapReference to {:x} length {}>'.format (self.address, self.length)
@property
def item (self):
if self._item:
return self._item
elif self.address in self.heap:
self._item = self.heap[self.address]
return self._item
else:
raise HeapReferenceUnresolved (self.address, self.length)
class HeapReferenceUnresolved (Exception):
def __init__ (self, address, length):
Exception.__init__ (self, 'addr: {:x}, len: {}'.format (address, length))
# Machine constants
intsize = 2
pagesize = 512
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