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#!/usr/bin/env python
# Fill in checksum/size of an option rom, and pad it to proper length.
#
# Copyright (C) 2009 Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import sys
def alignpos(pos, alignbytes):
mask = alignbytes - 1
return (pos + mask) & ~mask
def checksum(data):
ords = map(ord, data)
return sum(ords)
def main():
inname = sys.argv[1]
outname = sys.argv[2]
# Read data in
f = open(inname, 'rb')
data = f.read()
f.close()
count = len(data)
# Pad to a 512 byte boundary
data += "\0" * (alignpos(count, 512) - count)
count = len(data)
# Check if a pci header is present
pcidata = ord(data[24:25]) + (ord(data[25:26]) << 8)
if pcidata != 0:
data = data[:pcidata + 16] + chr(int(count/512)) + chr(0) + data[pcidata + 18:]
# Fill in size field; clear checksum field
data = data[:2] + chr(int(count/512)) + data[3:6] + "\0" + data[7:]
# Checksum rom
newsum = (256 - checksum(data)) & 0xff
data = data[:6] + chr(newsum) + data[7:]
# Write new rom
f = open(outname, 'wb')
f.write(data)
f.close()
if __name__ == '__main__':
main()
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