improve concatenate to create smaller UF2s

the prior version, for the board/user configs, took the whole ~2MB
binary file and converted it to a UF2, which made for a lot of chunks
that were just writing 0s, between the end of the firmware and the start
of the config(s). this changes the logic to build each portion as
separate UF2 chunks and then combine them.

Signed-off-by: Brian S. Stephan <bss@incorporeal.org>

gp2040ce_bintools/builder.py

@@ -95,15 +95,25 @@ def concatenate_firmware_and_storage_files(firmware_filename: str,
             user_config_binary = serialize_config_with_footer(config)
 
     with open(firmware_filename, 'rb') as firmware:
-        new_binary = combine_firmware_and_config(bytearray(firmware.read()), board_config_binary, user_config_binary,
+        firmware_binary = bytearray(firmware.read())
+
+    # create a sequential binary for .bin and USB uses, or index it for .uf2
+    if usb or combined_filename[-4:] != '.uf2':
+        new_binary = combine_firmware_and_config(firmware_binary, board_config_binary, user_config_binary,
                                                  replace_extra=replace_extra)
+    else:
+        new_binary = convert_binary_to_uf2(firmware_binary)
+        if board_config_binary:
+            new_binary += convert_binary_to_uf2(pad_config_to_storage_size(board_config_binary),
+                                                start=BOARD_CONFIG_BINARY_LOCATION)
+        if user_config_binary:
+            new_binary += convert_binary_to_uf2(pad_config_to_storage_size(user_config_binary),
+                                                start=USER_CONFIG_BINARY_LOCATION)
 
     if combined_filename:
         with open(combined_filename, 'wb') as combined:
-            if combined_filename[-4:] == '.uf2':
-                combined.write(convert_binary_to_uf2(new_binary))
-            else:
-                combined.write(new_binary)
+            combined.write(new_binary)
+
     if usb:
         endpoint_out, endpoint_in = get_bootsel_endpoints()
         write(endpoint_out, endpoint_in, GP2040CE_START_ADDRESS, bytes(new_binary))

tests/test_builder.py

@@ -3,6 +3,7 @@
 SPDX-FileCopyrightText: © 2023 Brian S. Stephan <bss@incorporeal.org>
 SPDX-License-Identifier: GPL-3.0-or-later
 """
+import math
 import os
 import sys
 import unittest.mock as mock
@@ -110,6 +111,33 @@ def test_concatenate_to_usb(tmp_path):
     assert len(mock_write.call_args.args[3]) == 2 * 1024 * 1024
 
 
+def test_concatenate_to_uf2(tmp_path, firmware_binary, config_binary):
+    """Test that we write a UF2 file as expected."""
+    tmp_file = os.path.join(tmp_path, 'concat.uf2')
+    firmware_file = os.path.join(HERE, 'test-files', 'test-firmware.bin')
+    config_file = os.path.join(HERE, 'test-files', 'test-config.bin')
+    concatenate_firmware_and_storage_files(firmware_file, binary_board_config_filename=config_file,
+                                           binary_user_config_filename=config_file,
+                                           combined_filename=tmp_file)
+    with open(tmp_file, 'rb') as file:
+        content = file.read()
+    # size of the file should be 2x firmware in 256 byte blocks + 2x padded board config + 2x padding user config
+    assert len(content) == 2 * (math.ceil(len(firmware_binary)/256) * 256) + 2 * STORAGE_SIZE + 2 * STORAGE_SIZE
+
+
+def test_concatenate_to_uf2_board_only(tmp_path, firmware_binary, config_binary):
+    """Test that we write a UF2 file as expected."""
+    tmp_file = os.path.join(tmp_path, 'concat.uf2')
+    firmware_file = os.path.join(HERE, 'test-files', 'test-firmware.bin')
+    config_file = os.path.join(HERE, 'test-files', 'test-config.bin')
+    concatenate_firmware_and_storage_files(firmware_file, binary_board_config_filename=config_file,
+                                           combined_filename=tmp_file)
+    with open(tmp_file, 'rb') as file:
+        content = file.read()
+    # size of the file should be 2x firmware in 256 byte blocks + 2x padded board config + 2x padding user config
+    assert len(content) == 2 * (math.ceil(len(firmware_binary)/256) * 256) + 2 * STORAGE_SIZE
+
+
 def test_padding_firmware(firmware_binary):
     """Test that firmware is padded to the expected size."""
     padded = pad_binary_up_to_user_config(firmware_binary)

tests/test_storage.py

@@ -3,6 +3,7 @@
 SPDX-FileCopyrightText: © 2023 Brian S. Stephan <bss@incorporeal.org>
 SPDX-License-Identifier: GPL-3.0-or-later
 """
+import math
 import os
 import sys
 import unittest.mock as mock
@@ -139,6 +140,15 @@ def test_convert_binary_to_uf2(whole_board_with_board_config_dump):
     assert uf2[524:528] == bytearray(b'\x00\x01\x00\x10')   # address to write the second chunk
 
 
+def test_convert_unaligned_binary_to_uf2(firmware_binary):
+    """Do some sanity checks in the attempt to convert a binary to a UF2."""
+    uf2 = storage.convert_binary_to_uf2(firmware_binary)
+    assert len(uf2) == math.ceil(len(firmware_binary)/256) * 512    # 256 byte complete/partial chunks -> 512 b chunks
+    assert uf2[0:4] == b'\x55\x46\x32\x0a' == b'UF2\n'      # proper magic
+    assert uf2[8:12] == bytearray(b'\x00\x20\x00\x00')      # family ID set
+    assert uf2[524:528] == bytearray(b'\x00\x01\x00\x10')   # address to write the second chunk
+
+
 def test_convert_binary_to_uf2_with_offsets(whole_board_with_board_config_dump):
     """Do some sanity checks in the attempt to convert a binary to a UF2."""
     uf2 = storage.convert_binary_to_uf2(whole_board_with_board_config_dump, start=storage.USER_CONFIG_BINARY_LOCATION)