Add data word packing functions

pycoax/coax/protocol.py

@@ -330,6 +330,12 @@ def unpack_command_word(word):
 
     return Command(command)
 
+def pack_data_word(byte, set_parity=True):
+    """Pack a data byte into a 10-bit data word."""
+    parity = odd_parity(byte) if set_parity else 0
+
+    return (byte << 2) | (parity << 1)
+
 def is_data_word(word):
     """Is data word bit set?"""
     return (word & 0x1) == 0
@@ -347,6 +353,10 @@ def unpack_data_word(word, check_parity=False):
 
     return byte
 
+def pack_data_words(bytes_, set_parity=True):
+    """Pack data bytes into 10-bit data words."""
+    return [pack_data_word(byte, set_parity=set_parity) for byte in bytes_]
+
 def unpack_data_words(words, check_parity=False):
     """Unpack the data bytes from 10-bit data words."""
     return bytes([unpack_data_word(word, check_parity=check_parity) for word in words])

pycoax/tests/test_protocol.py

@@ -4,7 +4,7 @@ from unittest.mock import Mock
 import context
 
 from coax import PollResponse, KeystrokePollResponse, ProtocolError
-from coax.protocol import Command, Status, TerminalId, Control, SecondaryControl, pack_command_word, unpack_command_word, unpack_data_word, unpack_data_words, _execute_read_command, _execute_write_command
+from coax.protocol import Command, Status, TerminalId, Control, SecondaryControl, pack_command_word, unpack_command_word, pack_data_word, unpack_data_word, pack_data_words, unpack_data_words, _execute_read_command, _execute_write_command
 
 class PollResponseTestCase(unittest.TestCase):
     def test_is_power_on_reset_complete(self):
@@ -111,6 +111,17 @@ class UnpackCommandWordTestCase(unittest.TestCase):
         with self.assertRaisesRegex(ProtocolError, 'Word does not have command bit set'):
             unpack_command_word(0b0001000100)
 
+class PackDataWordTestCase(unittest.TestCase):
+    def test(self):
+        self.assertEqual(pack_data_word(0x00), 0b0000000010)
+        self.assertEqual(pack_data_word(0x01), 0b0000000100)
+        self.assertEqual(pack_data_word(0xff), 0b1111111110)
+
+    def test_disable_set_parity(self):
+        self.assertEqual(pack_data_word(0x00, set_parity=False), 0b0000000000)
+        self.assertEqual(pack_data_word(0x01, set_parity=False), 0b0000000100)
+        self.assertEqual(pack_data_word(0xff, set_parity=False), 0b1111111100)
+
 class UnpackDataWordTestCase(unittest.TestCase):
     def test(self):
         self.assertEqual(unpack_data_word(0b0000000010), 0x00)
@@ -124,6 +135,10 @@ class UnpackDataWordTestCase(unittest.TestCase):
         with self.assertRaisesRegex(ProtocolError, 'Parity error'):
             unpack_data_word(0b0000000000, check_parity=True)
 
+class PackDataWordsTestCase(unittest.TestCase):
+    def test(self):
+        self.assertEqual(pack_data_words(bytes.fromhex('00 ff')), [0b0000000010, 0b1111111110])
+
 class UnpackDataWordsTestCase(unittest.TestCase):
     def test(self):
         self.assertEqual(unpack_data_words([0b0000000010, 0b1111111110]), bytes.fromhex('00 ff'))