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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, struct
from python23compat import as_bytes
def alignpos(pos, alignbytes):
mask = alignbytes - 1
return (pos + mask) & ~mask
def checksum(data):
if (sys.version_info > (3, 0)):
cksum = sum(data)
else:
cksum = sum(map(ord, data))
return struct.pack('<B', (0x100 - cksum) & 0xff)
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 += as_bytes("\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:
blocks = struct.pack('<H', int(count/512))
data = data[:pcidata + 16] + blocks + data[pcidata + 18:]
# Fill in size field; clear checksum field
blocks = struct.pack('<B', int(count/512))
data = data[:2] + blocks + data[3:6] + as_bytes("\0") + data[7:]
# Checksum rom
data = data[:6] + checksum(data) + data[7:]
# Write new rom
f = open(outname, 'wb')
f.write(data)
f.close()
if __name__ == '__main__':
main()
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