counter: use symbolic names for input pins, wait conditions, annotation rows

Replace magic numbers by symbolic references to (fixed and optional)
decoder input signals, .wait() conditions, as well as annotation rows.

Move some empty lines, to better reflect which code lines form groups of
similar activity ("blocks" that logically belong together).

1 files changed, 16 insertions, 12 deletions

diff --git a/decoders/counter/pd.py b/decoders/counter/pd.py
index 6dd8d91..696c8e9 100644
--- a/decoders/counter/pd.py
+++ b/decoders/counter/pd.py
@@ -19,6 +19,9 @@
 
 import sigrokdecode as srd
 
+(PIN_DATA, PIN_RESET) = range(2)
+(ROW_EDGE, ROW_WORD, ROW_RESET) = range(3)
+
 class Decoder(srd.Decoder):
     api_version = 3
     id = 'counter'
@@ -40,9 +43,9 @@ class Decoder(srd.Decoder):
         ('word_reset', 'Word reset'),
     )
     annotation_rows = (
-        ('edge_counts', 'Edges', (0,)),
-        ('word_counts', 'Words', (1,)),
-        ('word_resets', 'Word resets', (2,)),
+        ('edge_counts', 'Edges', (ROW_EDGE,)),
+        ('word_counts', 'Words', (ROW_WORD,)),
+        ('word_resets', 'Word resets', (ROW_RESET,)),
     )
     options = (
         {'id': 'data_edge', 'desc': 'Edges to count (data)', 'default': 'any',
@@ -77,23 +80,24 @@ class Decoder(srd.Decoder):
     def decode(self):
         opt_edge_map = {'rising': 'r', 'falling': 'f', 'any': 'e'}
 
-        condition = [{0: opt_edge_map[self.edge]}]
-
-        if self.has_channel(1):
-            self.have_reset = True
-            condition.append({1: opt_edge_map[self.options['reset_edge']]})
+        condition = [{PIN_DATA: opt_edge_map[self.edge]}]
+        self.have_reset = self.has_channel(PIN_RESET)
+        if self.have_reset:
+            cond_reset = len(condition)
+            condition.append({PIN_RESET: opt_edge_map[self.options['reset_edge']]})
 
         while True:
             self.wait(condition)
-            if self.have_reset and self.matched[1]:
+
+            if self.have_reset and self.matched[cond_reset]:
                 self.edge_count = 0
                 self.word_count = 0
-                self.putc(2, ['Word reset', 'Reset', 'Rst', 'R'])
+                self.putc(ROW_RESET, ['Word reset', 'Reset', 'Rst', 'R'])
                 continue
 
             self.edge_count += 1
+            self.putc(ROW_EDGE, [str(self.edge_count)])
 
-            self.putc(0, [str(self.edge_count)])
             if self.divider > 0 and (self.edge_count % self.divider) == 0:
                 self.word_count += 1
-                self.putc(1, [str(self.word_count)])
+                self.putc(ROW_WORD, [str(self.word_count)])