util/exynos/fixed_cksum.py

   1 #!/usr/bin/env python2
   2 #
   3 # Copyright (C) 2013 Google Inc.
   4 #
   5 # Redistribution and use in source and binary forms, with or without
   6 # modification, are permitted provided that the following conditions
   7 # are met:
   8 # 1. Redistributions of source code must retain the above copyright
   9 #    notice, this list of conditions and the following disclaimer.
  10 # 2. Redistributions in binary form must reproduce the above copyright
  11 #    notice, this list of conditions and the following disclaimer in the
  12 #    documentation and/or other materials provided with the distribution.
  13 # 3. The name of the author may not be used to endorse or promote products
  14 #    derived from this software without specific prior written permission.
  15 #
  16 # THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17 # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19 # ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20 # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21 # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22 # OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23 # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25 # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26 # SUCH DAMAGE.
  27
  28 """
  29 This utility computes and fills Exynos ROM checksum (for BL1 or BL2).
  30 (Algorithm from U-Boot: tools/mkexynosspl.c)
  31
  32 Input: IN OUT DATA_SIZE
  33
  34 Output:
  35
  36   IN padded out to DATA_SIZE, checksum at the end, written to OUT.
  37 """
  38
  39 import struct
  40 import sys
  41
  42 def main(argv):
  43   if len(argv) != 4:
  44     exit('usage: %s IN OUT DATA_SIZE' % argv[0])
  45
  46   in_name, out_name = argv[1:3]
  47   size = int(argv[3], 0)
  48   checksum_format = "<I"
  49   with open(in_name, "rb") as in_file, open(out_name, "wb") as out_file:
  50     data = in_file.read()
  51     checksum_size = struct.calcsize(checksum_format)
  52     data_size = size - checksum_size
  53     assert len(data) <= data_size
  54     checksum = struct.pack(checksum_format, sum(map(ord, data)))
  55     out_file.write(data + bytearray(data_size - len(data)) + checksum)
  56
  57
  58 if __name__ == '__main__':
  59   main(sys.argv)