def _parsetemplate(self, template):
if isinstance(template, str): template = [template]
# remove spaces from template
tmplstr = re.sub('\s+', '', template[0])
# if template is shorter than data, don't match
data = self.data.rstrip('\0')
if len(data) > len(tmplstr)/2: return False
# pad data with zeroes to match with template
data = self.data + '\0'*max(0, len(tmplstr)/2-len(self.data))
# create template data with variables set to zero to be able to use getdata()
tmpldatastr = re.sub('[^0-9a-f]', '0', tmplstr)
tmpldata = ''.join([chr(int(tmpldatastr[i:i+2], 16)) for i in range(0, len(tmpldatastr), 2)])
# determine fields and their nibble-offsets from template
fields = [] # field names (or '0' for literal)
tmploffsets = [] # offsets of fields from template
lastchar = None
for i in range(len(tmplstr)):
curchar = tmplstr[i]
if curchar in '0123456789abcdef': curchar = '0'
if curchar != lastchar:
fields.append(curchar)
tmploffsets.append(i*4)
lastchar = curchar
tmploffsets.append(len(tmplstr)*4)
# determine field boundaries, in the following order:
# 1. specified start-offsets, if any
# 1b. apply fixed-width fields with known start-offsets
# 2. boundaries of template characters
# 2b. apply fixed-width fields with known start-offsets
# 3. boundaries of template literals
offsets = [None] * (len(fields)+1)
if len(template) > 1 and template[1]:
for fchar,bitoffs in template[1].iteritems():
offsets[fields.index(fchar)] = tmplstr.find(fchar)*4 + bitoffs
self._apply_fixedwidth(fields, offsets)
# boundaries of template characters
for i in range(len(tmploffsets)-1):
if offsets[i] is not None: continue
if fields[i] == '0': continue
offsets[i] = tmploffsets[i]
self._apply_fixedwidth(fields, offsets)
# boundaries of template literals
for i in range(len(tmploffsets)):
if offsets[i] is not None: continue
offsets[i] = tmploffsets[i]
self._apply_fixedwidth(fields, offsets)
# now parse all fields
fieldvalues={}
for i in range(len(fields)):
value = getbits(data, offsets[i], offsets[i+1])
curchar = fields[i]
if curchar == '0':
# literal: check with template
tmplvalue = getbits(tmpldata, offsets[i], offsets[i+1])
if tmplvalue != value: return False
else:
# template variable: store
fname, fchar, flen, ftype = self._field_by_char(curchar)
try: fieldvalues[fname] = ftype(value, obj=self, width=(offsets[i+1]-offsets[i]+3)/4)
except TypeError: fieldvalues[fname] = ftype(value)
# everything is ok, incorporate fields
self.__dict__.update(fieldvalues)
return True
def getbits(self, start, end): # return number at bit positions of data (0 is beginning) return getbits(self.data, start, end)