Merge iplboot into final UF2

CMakeLists.txt

@@ -33,3 +33,17 @@ target_include_directories(picoboot PRIVATE src)
 target_link_libraries(picoboot PRIVATE pico_stdlib hardware_pio hardware_dma)
 
 pico_add_extra_outputs(picoboot)
+
+function(merge_uf2 NAME BASE_TARGET INPUTS)
+        get_target_property(BASE_TARGET_NAME ${BASE_TARGET} OUTPUT_NAME)
+        if(BASE_TARGET_NAME STREQUAL "BASE_TARGET_NAME-NOTFOUND")
+                get_target_property(BASE_TARGET_NAME ${BASE_TARGET} NAME)
+        endif()
+
+        add_custom_target(${NAME} ALL
+                COMMAND ${CMAKE_CURRENT_LIST_DIR}/merge_uf2.py ${NAME}.uf2 ${BASE_TARGET_NAME}.uf2 ${INPUTS}
+                DEPENDS ${BASE_TARGET} ${INPUTS}
+                COMMAND_EXPAND_LISTS)
+endfunction()
+
+merge_uf2(picoboot_full picoboot "${CMAKE_CURRENT_LIST_DIR}/iplboot.uf2")

merge_uf2.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+
+from dataclasses import dataclass
+import itertools
+import struct
+import sys
+
+block_format = "< 8I 476B I"
+magic0 = 0x0A324655 # "UF2\n"
+magic1 = 0x9E5D5157
+magic2 = 0x0AB16F30
+
+@dataclass
+class Uf2Block:
+    # Fields are ordered as they appear in the serialized binary
+    # DO NOT CHANGE
+    flags: int
+    address: int
+    size: int
+    seq: int
+    total_blocks: int
+    family_id: int
+    data: bytes = bytes()
+
+def read_file(name):
+    with open(name, "rb") as f:
+        data = f.read()
+    return data
+
+def decode_uf2(data):
+    while data:
+        block, data = data[:512], data[512:]
+        block = struct.unpack(block_format, block)
+
+        header, body, footer = block[:8], block[8:-1], block[-1:]
+        assert (header[:2], footer) == ((magic0, magic1), (magic2,))
+
+        block = Uf2Block(*header[2:])
+        block.data = bytes(body[:block.size])
+
+        yield block
+
+def write_uf2(blocks, name):
+    with open(name, "wb") as f:
+        for seq, b in enumerate(blocks):
+            data = struct.pack(
+                block_format,
+                magic0,
+                magic1,
+                b.flags,
+                b.address,
+                b.size,
+                seq,
+                len(blocks),
+                b.family_id,
+                *b.data.ljust(476, b"\x00"),
+                magic2,
+            )
+            f.write(data)
+
+def main():
+    output = sys.argv[1]
+    inputs = sys.argv[2:]
+
+    inputs = (read_file(f) for f in inputs)
+    inputs = (decode_uf2(f) for f in inputs)
+
+    blocks = [b for b in itertools.chain.from_iterable(inputs)]
+
+    ref = blocks[0]
+    for b in blocks:
+        assert b.flags == ref.flags
+        assert b.size <= ref.size
+        assert b.family_id == ref.family_id
+
+    blocks.sort(key=lambda b: b.address)
+    for a, b in itertools.pairwise(blocks):
+        # Ensure no blocks overlap
+        assert a.address + a.size <= b.address
+
+    write_uf2(blocks, output)
+
+if __name__ == "__main__":
+    sys.exit(main())