#!/usr/bin/env python3 # # SPDX-License-Identifier: BSD-3-Clause """ This utility computes and fills Exynos ROM checksum (for BL1 or BL2). (Algorithm from U-Boot: tools/mkexynosspl.c) Input: IN OUT DATA_SIZE Output: IN padded out to DATA_SIZE, checksum at the end, written to OUT. """ import struct import sys def main(argv): if len(argv) != 4: exit('usage: %s IN OUT DATA_SIZE' % argv[0]) in_name, out_name = argv[1:3] size = int(argv[3], 0) checksum_format = "<I" with open(in_name, "rb") as in_file, open(out_name, "wb") as out_file: data = in_file.read() checksum_size = struct.calcsize(checksum_format) data_size = size - checksum_size assert len(data) <= data_size checksum = struct.pack(checksum_format, sum(data)) out_file.write(data + bytearray(data_size - len(data)) + checksum) if __name__ == '__main__': main(sys.argv)