update: parallel and usb_signalling decoder

Author: dreamsource-tai

libsigrokdecode4DSL/decoders/parallel/pd.py

@@ -184,9 +184,10 @@ def handel_word(self, item, cur_dex):
     def end(self): 
         cur_dex = self.last_samplenum
         #the last annotation
-        self.put_py(self.prv_dex, cur_dex, ['ITEM', self.saved_item])
-        self.put_ann(self.prv_dex, cur_dex, [0, [self.fmt_item.format(self.saved_item)]])
-        self.handel_word(None, cur_dex)
+        if self.saved_item != None:
+            self.put_py(self.prv_dex, cur_dex, ['ITEM', self.saved_item])
+            self.put_ann(self.prv_dex, cur_dex, [0, [self.fmt_item.format(self.saved_item)]])
+            self.handel_word(None, cur_dex)
 
     def decode(self):
         # Determine which (optional) channels have input data. Insist in
@@ -227,9 +228,9 @@ def decode(self):
         num_word_items = self.options['wordsize']
         num_word_bits = num_item_bits * num_word_items
         num_digits = (num_item_bits + 3) // 4
-        self.fmt_item = "{{:0{}X}}".format(num_digits)
+        self.fmt_item = "@{{:0{}X}}".format(num_digits)
         num_digits = (num_word_bits + 3) // 4
-        self.fmt_word = "{{:0{}X}}".format(num_digits)
+        self.fmt_word = "@{{:0{}X}}".format(num_digits)
         self.num_item_bits = num_item_bits
 
         # Keep processing the input stream. Assume "always zero" for

libsigrokdecode4DSL/decoders/usb_signalling/pd.py

@@ -163,12 +163,12 @@ def metadata(self, key, value):
         if key == srd.SRD_CONF_SAMPLERATE:
             self.samplerate = value
             self.signalling = self.options['signalling']
-            if self.signalling != 'automatic':
-                self.update_bitrate()
+            self.update_bitrate()
 
-    def update_bitrate(self):
-        self.bitrate = bitrates[self.signalling]
-        self.bitwidth = float(self.samplerate) / float(self.bitrate)
+    def update_bitrate(self): 
+        if self.signalling != 'automatic':
+            self.bitrate = bitrates[self.signalling]
+            self.bitwidth = float(self.samplerate) / float(self.bitrate)
 
     def putpx(self, data):
         s = self.samplenum_edge