52 lines
1.7 KiB
Plaintext
52 lines
1.7 KiB
Plaintext
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#!/usr/bin/env python2
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#
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# Compute and insert the vector table checksum required for booting the
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# LPC43xx and some other NXP ARM microcontrollers.
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#
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# usage: lpcvtcksum firmware.bin
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#
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# This file is part of the libopencm3 project.
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#
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# Copyright (C) 2012 Michael Ossmann <mike@ossmann.com>
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#
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# This library is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with this library. If not, see <http://www.gnu.org/licenses/>.
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import sys, struct
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binfile = open(sys.argv[1], 'r+b')
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rawvectors = binfile.read(32)
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vectors = list(struct.unpack('<IIIIIIII', rawvectors))
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# compute vector table checksum
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sum = 0
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for i in range(7):
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sum += vectors[i]
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vectors[7] = 1 + (0xffffffff ^ (0xffffffff & sum))
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print "computed vector table checksum: 0x%08x" % vectors[7]
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rawremainder = binfile.read()
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remainder = list(struct.unpack('B' * len(rawremainder), rawremainder))
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numbytes = len(remainder) + 32
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# pad to multiple of 4096 bytes to make GoodFET happy
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if (numbytes % 4096):
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remainder.extend([0] * (4096 - numbytes % 4096))
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# rewrite file with checksum and padding
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data = vectors
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data.extend(remainder)
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binfile.seek(0)
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binfile.write(struct.pack('<IIIIIIII' + 'B' * len(remainder), *data))
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