util/exynos/variable_cksum.py

   1 #!/usr/bin/env python3
   2 #
   3 # SPDX-License-Identifier: BSD-3-Clause
   4
   5 """
   6 This utility computes and fills Exynos ROM checksum (for BL1 or BL2).
   7 (Algorithm from U-Boot: tools/mkexynosspl.c)
   8
   9 Input: IN OUT
  10
  11 Output:
  12
  13   Checksum header added to IN and written to OUT.
  14   Header: uint32_t size, checksum, reserved[2].
  15 """
  16
  17 import struct
  18 import sys
  19
  20 def main(argv):
  21   if len(argv) != 3:
  22     exit('usage: %s IN OUT' % argv[0])
  23
  24   in_name, out_name = argv[1:3]
  25   header_format = "<IIII"
  26   with open(in_name, "rb") as in_file, open(out_name, "wb") as out_file:
  27     data = in_file.read()
  28     header = struct.pack(header_format,
  29                          struct.calcsize(header_format) + len(data),
  30                          sum(data),
  31                          0, 0)
  32     out_file.write(header + data)
  33
  34
  35 if __name__ == '__main__':
  36   main(sys.argv)