seven_segment: document segment layout for awareness during maintenance

Add a comment to the table which maps LED segment combinations to their
textual presentation. Mention the table's sort order for awareness, and
provide column captions as well as a segment layout illustration to
simplify maintenance.

The LED segment layout comment was
Submitted-by: Ben Gardiner <redacted>

diff --git a/decoders/seven_segment/pd.py b/decoders/seven_segment/pd.py
index d090cfffc5c546328820146f150e2d41cba47d44..5708fd500e46314e6505f6aa5cf0758e463220e2 100644 (file)
--- a/decoders/seven_segment/pd.py
+++ b/decoders/seven_segment/pd.py
@@ -22,6 +22,18 @@ import sigrokdecode as srd
 class ChannelError(Exception):
     pass
 
+# This table is sorted by ASCII code numbers, with the exception
+# of letters having their upper/lower case ignored.
+#
+# Traditional LED segment names and layout:
+#
+#      A
+#    F   B
+#      G
+#    E   C
+#      D
+#
+#    A  B  C  D  E  F  G
 digits = {
     (0, 0, 0, 0, 0, 0, 0): ' ',
     (0, 1, 0, 0, 0, 1, 0): '"',