Improve encode/decode comments

pvcraven · Feb 2, 2021 · 0792009 · 0792009
1 parent 9a3a7c6
commit 0792009
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/decode_message_3.py b/decode_message_3.py
@@ -4,6 +4,7 @@
 CLOCK_CHANNEL = 16
 DATA_CHANNEL = 23
 
+
 # This is a callback function that will be called whenever we have a high/low
 # or low/high change in the signal.
 def my_callback(channel):
@@ -20,6 +21,7 @@ def my_callback(channel):
         my_callback.counter = 0
         my_callback.result_byte = 0
 
+
 my_callback.counter = 0
 my_callback.result_byte = 0
 

diff --git a/encode_message.py b/encode_message.py
@@ -28,9 +28,17 @@
     # significant bit 7, down to 0.
     for bit_pos in range(bits_in_a_byte - 1, -1, -1):
 
+        # Next line is complicated.
         # Use a single 1, and bit shift it with << to the
-        # spot we are interested in. Then use a bitwise
-        # and to see if that spot has a value
+        # spot we are interested in. Then use a bitwise and (&)
+        # and to see if that spot has a value.
+        # if bit pos = 6 then
+        #   1 << 6 = 0100 0000 = 64
+        # if my_byte = 'H' which ASCII 72 = 0100 1000 binary
+        # H      = 0100 1000
+        # 1 << 6 = 0100 0000
+        #          ---------
+        # &      = 0100 0000 = 64 (result of bit-wise 'and')
         bit = (1 << bit_pos) & my_byte
 
         if bit != 0: