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- #!/usr/bin/python
- #
- # Compute and insert the vector table checksum required for booting the
- # LPC43xx and some other NXP ARM microcontrollers.
- #
- # usage: lpcvtcksum firmware.bin
- #
- # This file is part of the libopencm3 project.
- #
- # Copyright (C) 2012 Michael Ossmann <mike@ossmann.com>
- #
- # This library is free software: you can redistribute it and/or modify
- # it under the terms of the GNU Lesser General Public License as published by
- # the Free Software Foundation, either version 3 of the License, or
- # (at your option) any later version.
- #
- # This library is distributed in the hope that it will be useful,
- # but WITHOUT ANY WARRANTY; without even the implied warranty of
- # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- # GNU Lesser General Public License for more details.
- #
- # You should have received a copy of the GNU Lesser General Public License
- # along with this library. If not, see <http://www.gnu.org/licenses/>.
-
- import sys, struct
-
- binfile = open(sys.argv[1], 'r+b')
- rawvectors = binfile.read(32)
- vectors = list(struct.unpack('<IIIIIIII', rawvectors))
-
- # compute vector table checksum
- sum = 0
- for i in range(7):
- sum += vectors[i]
- vectors[7] = 1 + (0xffffffff ^ (0xffffffff & sum))
-
- print "computed vector table checksum: 0x%08x" % vectors[7]
-
- rawremainder = binfile.read()
- remainder = list(struct.unpack('B' * len(rawremainder), rawremainder))
- numbytes = len(remainder) + 32
-
- # pad to multiple of 4096 bytes to make GoodFET happy
- if (numbytes % 4096):
- remainder.extend([0] * (4096 - numbytes % 4096))
-
- # rewrite file with checksum and padding
- data = vectors
- data.extend(remainder)
- binfile.seek(0)
- binfile.write(struct.pack('<IIIIIIII' + 'B' * len(remainder), *data))
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