mirror of https://github.com/ARMmbed/mbed-os.git
35 lines
1.3 KiB
Python
35 lines
1.3 KiB
Python
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"""
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http://www.nxp.com/documents/user_manual/UM10360.pdf
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32.3.1.1 Criterion for Valid User Code
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The reserved Cortex-M3 exception vector location 7 (offset 0x1C in the vector table)
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should contain the 2's complement of the check-sum of table entries 0 through 6. This
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causes the checksum of the first 8 table entries to be 0. The boot loader code checksums
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the first 8 locations in sector 0 of the flash. If the result is 0, then execution control is
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transferred to the user code.
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"""
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from struct import unpack, pack
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def patch(bin_path):
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with open(bin_path, 'r+b') as bin:
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# Read entries 0 through 6 (Little Endian 32bits words)
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vector = [unpack('<I', bin.read(4))[0] for _ in range(7)]
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# location 7 (offset 0x1C in the vector table) should contain the 2's
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# complement of the check-sum of table entries 0 through 6
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bin.seek(0x1C)
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bin.write(pack('<I', (~sum(vector) + 1) & 0xFFFFFFFF))
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def is_patched(bin_path):
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with open(bin_path, 'rb') as bin:
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# The checksum of the first 8 table entries should be 0
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return (sum([unpack('<I', bin.read(4))[0] for _ in range(8)]) & 0xFFFFFFFF) == 0
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if __name__ == '__main__':
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bin_path = "C:/Users/emimon01/releases/emilmont/build/test/LPC1768/ARM/MBED_A1/basic.bin"
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patch(bin_path)
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assert is_patched(bin_path), "The file is not patched"
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