2 # Option ROM signing utility
5 # Jan Kiszka <jan.kiszka@siemens.com>
7 # This work is licensed under the terms of the GNU GPL, version 2 or later.
8 # See the COPYING file in the top-level directory.
14 print('usage: signrom.py input output')
17 fin
= open(sys
.argv
[1], 'rb')
18 fout
= open(sys
.argv
[2], 'wb')
21 size_byte
= ord(fin
.read(1))
25 # If the caller left the size field blank then we will fill it in,
26 # also rounding the whole input to a multiple of 512 bytes.
28 # +1 because we need a byte to store the checksum.
30 # Round up to next multiple of 512.
34 sys
.exit("%s: option ROM size too large" % sys
.argv
[1])
35 # size-1 because a final byte is added below to store the checksum.
36 data
= data
.ljust(size
-1, '\0')
37 data
= data
[:2] + chr(size
/512) + data
[3:]
39 # Otherwise the input file specifies the size so use it.
40 # -1 because we overwrite the last byte of the file with the checksum.
41 size
= size_byte
* 512 - 1
48 # catch Python 2 vs. 3 differences
49 if isinstance(b
, int):
53 checksum
= (256 - checksum
) % 256
55 # Python 3 no longer allows chr(checksum)
56 fout
.write(struct
.pack('B', checksum
))