circuitpython/ports/esp32/makeimg.py

import sys

OFFSET_BOOTLOADER = 0x1000
OFFSET_PARTITIONS = 0x8000
OFFSET_APPLICATION = 0x10000

files_in = [
    ("bootloader", OFFSET_BOOTLOADER, sys.argv[1]),
    ("partitions", OFFSET_PARTITIONS, sys.argv[2]),
    ("application", OFFSET_APPLICATION, sys.argv[3]),
]
file_out = sys.argv[4]

cur_offset = OFFSET_BOOTLOADER
with open(file_out, "wb") as fout:
    for name, offset, file_in in files_in:
        assert offset >= cur_offset
        fout.write(b"\xff" * (offset - cur_offset))
        cur_offset = offset
        with open(file_in, "rb") as fin:
            data = fin.read()
            fout.write(data)
            cur_offset += len(data)
            print("%-12s% 8d" % (name, len(data)))
    print("%-12s% 8d" % ("total", cur_offset))