graycode, morse, pwm, usb_request, wiegand: cope with absent sample rate

Improve robustness of some more protocol decoders. Few of them never
checked for the availability of a sample rate in the first place, others
checked for the presence of a spec but would not cope with a value of 0.
Some checked the value only after processing it, which could result in
runtime errors.

This change is motivated by bug #1118.

1 files changed, 7 insertions, 0 deletions

diff --git a/decoders/pwm/pd.py b/decoders/pwm/pd.py
index 2301523..9770445 100644
--- a/decoders/pwm/pd.py
+++ b/decoders/pwm/pd.py
@@ -20,6 +20,9 @@
 
 import sigrokdecode as srd
 
+class SamplerateError(Exception):
+    pass
+
 class Decoder(srd.Decoder):
     api_version = 3
     id = 'pwm'
@@ -52,6 +55,7 @@ class Decoder(srd.Decoder):
         self.reset()
 
     def reset(self):
+        self.samplerate = None
         self.ss_block = self.es_block = None
 
     def metadata(self, key, value):
@@ -89,6 +93,9 @@ class Decoder(srd.Decoder):
         self.put(self.ss_block, self.es_block, self.out_binary, data)
 
     def decode(self):
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
+
         num_cycles = 0
         average = 0