text: #!/usr/bin/python
  
  # Written by Antonio Galea - 2010/11/18
  # Distributed under Gnu LGPL 3.0
  # see http://www.gnu.org/licenses/lgpl-3.0.txt
  
  import sys,struct,zlib,os
  import binascii
  from optparse import OptionParser
  
  DEFAULT_DEVICE="0x0483:0xdf11"
  DEFAULT_NAME=b'ST...'
  
  def named(tuple,names):
    return dict(list(zip(names.split(),tuple)))
  def consume(fmt,data,names):
    n = struct.calcsize(fmt)
    return named(struct.unpack(fmt,data[:n]),names),data[n:]
  def cstring(bytestring):
    return bytestring.partition(b'\0')[0]
  def compute_crc(data):
    return 0xFFFFFFFF & -zlib.crc32(data) -1
  
  def parse(file,dump_images=False):
    print('File: "%s"' % file)
    data = open(file,'rb').read()
    crc = compute_crc(data[:-4])
    prefix, data = consume('<5sBIB',data,'signature version size targets')
    print('%(signature)s v%(version)d, image size: %(size)d, targets: %(targets)d' % prefix)
    for t in range(prefix['targets']):
      tprefix, data  = consume('<6sBI255s2I',data,'signature altsetting named name size elements')
      tprefix['num'] = t
      if tprefix['named']:
        tprefix['name'] = cstring(tprefix['name'])
      else:
        tprefix['name'] = ''
      print('%(signature)s %(num)d, alt setting: %(altsetting)s, name: "%(name)s", size: %(size)d, elements: %(elements)d' % tprefix)
      tsize = tprefix['size']
      target, data = data[:tsize], data[tsize:]
      for e in range(tprefix['elements']):
        eprefix, target = consume('<2I',target,'address size')
        eprefix['num'] = e
        print('  %(num)d, address: 0x%(address)08x, size: %(size)d' % eprefix)
        esize = eprefix['size']
        image, target = target[:esize], target[esize:]
        if dump_images:
          out = '%s.target%d.image%d.bin' % (file,t,e)
          open(out,'wb').write(image)
          print('    DUMPED IMAGE TO "%s"' % out)
      if len(target):
        print("target %d: PARSE ERROR" % t)
    suffix = named(struct.unpack('<4H3sBI',data[:16]),'device product vendor dfu ufd len crc')
    print('usb: %(vendor)04x:%(product)04x, device: 0x%(device)04x, dfu: 0x%(dfu)04x, %(ufd)s, %(len)d, 0x%(crc)08x' % suffix)
    if crc != suffix['crc']:
      print("CRC ERROR: computed crc32 is 0x%08x" % crc)
    data = data[16:]
    if data:
      print("PARSE ERROR")
  
  def checkbin(binfile):
    data = open(binfile,'rb').read()
    if (len(data) < 16):
      return
    crc = compute_crc(data[:-4])
    suffix = named(struct.unpack('<4H3sBI',data[-16:]),'device product vendor dfu ufd len crc')
    if crc == suffix['crc'] and suffix['ufd'] == b'UFD':
      print('usb: %(vendor)04x:%(product)04x, device: 0x%(device)04x, dfu: 0x%(dfu)04x, %(ufd)s, %(len)d, 0x%(crc)08x' % suffix)
      print("It looks like the file %s has a DFU suffix!" % binfile)
      print("Please remove any DFU suffix and retry.")
      sys.exit(1)
  
  def build(file,targets,name=DEFAULT_NAME,device=DEFAULT_DEVICE):
    data = b''
    for t,target in enumerate(targets):
      tdata = b''
      for image in target:
        tdata += struct.pack('<2I',image['address'],len(image['data']))+image['data']
      tdata = struct.pack('<6sBI255s2I',b'Target',0,1,name,len(tdata),len(target)) + tdata
      data += tdata
    data  = struct.pack('<5sBIB',b'DfuSe',1,len(data)+11,len(targets)) + data
    v,d=[int(x,0) & 0xFFFF for x in device.split(':',1)]
    data += struct.pack('<4H3sB',0,d,v,0x011a,b'UFD',16)
    crc   = compute_crc(data)
    data += struct.pack('<I',crc)
    open(file,'wb').write(data)
  
  if __name__=="__main__":
    usage = """
  %prog [-d|--dump] infile.dfu
  %prog {-b|--build} address:file.bin [-b address:file.bin ...] [{-D|--device}=vendor:device] outfile.dfu
  %prog {-s|--build-s19} file.s19 [{-D|--device}=vendor:device] outfile.dfu"""
    parser = OptionParser(usage=usage)
    parser.add_option("-b", "--build", action="append", dest="binfiles",
      help="build a DFU file from given BINFILES. Note that the BINFILES must not have any DFU suffix!", metavar="BINFILES")
    parser.add_option("-s", "--build-s19", type="string", dest="s19files",
      help="build a DFU file from given S19 S-record file.", metavar="S19FILE")
    parser.add_option("-D", "--device", action="store", dest="device",
      help="build for DEVICE, defaults to %s" % DEFAULT_DEVICE, metavar="DEVICE")
    parser.add_option("-d", "--dump", action="store_true", dest="dump_images",
      default=False, help="dump contained images to current directory")
    (options, args) = parser.parse_args()
  
    if options.binfiles and len(args)==1:
      target = []
      for arg in options.binfiles:
        try:
          address,binfile = arg.split(':',1)
        except ValueError:
          print("Address:file couple '%s' invalid." % arg)
          sys.exit(1)
        try:
          address = int(address,0) & 0xFFFFFFFF
        except ValueError:
          print("Address %s invalid." % address)
          sys.exit(1)
        if not os.path.isfile(binfile):
          print("Unreadable file '%s'." % binfile)
          sys.exit(1)
        checkbin(binfile)
        target.append({ 'address': address, 'data': open(binfile,'rb').read() })
      outfile = args[0]
      device = DEFAULT_DEVICE
      if options.device:
        device=options.device
      try:
        v,d=[int(x,0) & 0xFFFF for x in device.split(':',1)]
      except:
        print("Invalid device '%s'." % device)
        sys.exit(1)
      build(outfile,[target],DEFAULT_NAME,device)
    elif options.s19files and len(args)==1:
      address = 0
      data = ""
      target = []
      name = DEFAULT_NAME
      with open(options.s19files) as f:
        lines = f.readlines()
        for line in lines:
            curaddress = 0
            curdata = ""
            line = line.rstrip()
            if line.startswith ( "S0" ):
              name = binascii.a2b_hex(line[8:len(line) - 2]).replace(".s19", "")
            elif line.startswith ( "S3" ):
              try:
                curaddress = int(line[4:12], 16) & 0xFFFFFFFF
              except ValueError:
                print("Address %s invalid." % address)
                sys.exit(1)
              curdata = binascii.unhexlify(line[12:-2])
            elif line.startswith ( "S2" ):
              try:
                curaddress = int(line[4:10], 16) & 0xFFFFFFFF
              except ValueError:
                print("Address %s invalid." % address)
                sys.exit(1)
              curdata = binascii.unhexlify(line[10:-2])
            elif line.startswith ( "S1" ):
              try:
                curaddress = int(line[4:8], 16) & 0xFFFFFFFF
              except ValueError:
                print("Address %s invalid." % address)
                sys.exit(1)
              curdata = binascii.unhexlify(line[8:-2])
            if address == 0:
                address = curaddress
                data = curdata
            elif address + len(data) != curaddress:
                target.append({ 'address': address, 'data': data })
                address = curaddress
                data = curdata
            else:
                data += curdata
      outfile = args[0]
      device = DEFAULT_DEVICE
      if options.device:
        device=options.device
      try:
        v,d=[int(x,0) & 0xFFFF for x in device.split(':',1)]
      except:
        print("Invalid device '%s'." % device)
        sys.exit(1)
      build(outfile,[target],name,device)
    elif len(args)==1:
      infile = args[0]
      if not os.path.isfile(infile):
        print("Unreadable file '%s'." % infile)
        sys.exit(1)
      parse(infile, dump_images=options.dump_images)
    else:
      parser.print_help()
      sys.exit(1)
  