diff options
Diffstat (limited to 'libopencm3/scripts/lpcvtcksum')
-rwxr-xr-x | libopencm3/scripts/lpcvtcksum | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/libopencm3/scripts/lpcvtcksum b/libopencm3/scripts/lpcvtcksum new file mode 100755 index 0000000..27dc8a7 --- /dev/null +++ b/libopencm3/scripts/lpcvtcksum @@ -0,0 +1,51 @@ +#!/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)) |