4 # Option ROM signing utility
7 # Jan Kiszka <jan.kiszka@siemens.com>
9 # This work is licensed under the terms of the GNU GPL, version 2 or later.
10 # See the COPYING file in the top-level directory.
16 print('usage: signrom.py input output')
19 fin
= open(sys
.argv
[1], 'rb')
20 fout
= open(sys
.argv
[2], 'wb')
23 if magic
!= b
'\x55\xaa':
24 sys
.exit("%s: option ROM does not begin with magic 55 aa" % sys
.argv
[1])
26 size_byte
= ord(fin
.read(1))
30 size
= size_byte
* 512
32 sys
.stderr
.write('error: ROM is too large (%d > %d)\n' % (len(data
), size
))
34 elif len(data
) < size
:
35 # Add padding if necessary, rounding the whole input to a multiple of
36 # 512 bytes according to the third byte of the input.
37 # size-1 because a final byte is added below to store the checksum.
38 data
= data
.ljust(size
-1, b
'\0')
40 if ord(data
[-1:]) != 0:
41 sys
.stderr
.write('WARNING: ROM includes nonzero checksum\n')
48 checksum
= (checksum
- b
) & 255
50 fout
.write(struct
.pack('B', checksum
))