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#!/usr/bin/env python2
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# 3. The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
"""
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(map(ord, data)))
out_file.write(data + bytearray(data_size - len(data)) + checksum)
if __name__ == '__main__':
main(sys.argv)
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