add method to generate a serialized + footer config

gp2040ce_bintools/storage.py

@@ -144,6 +144,17 @@ def pad_config_to_storage_size(config: bytes) -> bytearray:
 
     return bytearray(b'\x00' * bytes_to_pad) + bytearray(config)
 
+
+def serialize_config_with_footer(config: Message) -> bytearray:
+    """Given a config, generate the config footer as expected by GP2040-CE."""
+    config_bytes = config.SerializeToString()
+    config_size = bytes(reversed(config.ByteSize().to_bytes(4, 'big')))
+    config_crc = bytes(reversed(binascii.crc32(config_bytes).to_bytes(4, 'big')))
+    config_magic = FOOTER_MAGIC
+
+    return config_bytes + config_size + config_crc + config_magic
+
+
 ############
 # COMMANDS #
 ############

tests/test_storage.py

@@ -105,6 +105,26 @@ def test_config_from_whole_board_parses(whole_board_dump):
     assert config.hotkeyOptions.hotkeyF1Up.dpadMask == 1
 
 
+@with_pb2s
+def test_serialize_config_with_footer(storage_dump):
+    """Test that reserializing a read in config matches the original."""
+    config = storage.get_config(storage_dump)
+    assert config.boardVersion == 'v0.7.2'
+    reserialized = storage.serialize_config_with_footer(config)
+    assert storage_dump[-12:] == reserialized[-12:]
+
+
+@with_pb2s
+def test_serialize_modified_config_with_footer(storage_dump):
+    """Test that we can serialize a modified config."""
+    config = storage.get_config(storage_dump)
+    config.boardVersion == 'v0.7.2-cool'
+    serialized = storage.serialize_config_with_footer(config)
+    config_size, _, _ = storage.get_config_footer(serialized)
+    assert config_size == config.ByteSize()
+    assert len(serialized) == config_size + 12
+
+
 def test_pad_config_to_storage(config_binary):
     """Test that we can properly pad a config section to the correct storage section size."""
     storage_section = storage.pad_config_to_storage_size(config_binary)