def getTrailer(signature, sigTypeDescrip, descripFixedSize, sigFixedSize):
"""
create a trailer which has the following format
[a + b + c], where
a = signature type description
(Use fixed size to store it. Use zero to fill up the rest if description size is smaller than fixed size)
b = size of signature
(converted into hexadecimal representation in 32 bits in little endian format)
c = signature
(Used fixed size to store it. Use zero to fill up the rest if signature size is smaller than fixed size)
:param signature:
:param sigTypeDescrip: signature type description
:param descripFixedSize: fixed size in bytes for storing signature type description
:param sigFixedSize: fixed size in bytes for storing signature
:return:
"""
trailer = bytearray()
# append signature type description to fixed
sigTypeDescrip = bytearray(source=sigTypeDescrip, encoding="utf-8")
typeDescripSize = len(sigTypeDescrip)
if typeDescripSize > descripFixedSize:
raise Exception(
"Signature type description exceeded allowed size! Description size: "
+ sigTypeDescrip + ". Allowed maximum size: " + descripFixedSize +
". Description given: " + sigTypeDescrip)
padSize = descripFixedSize - typeDescripSize
pad = bytearray(padSize)
trailer.extend(sigTypeDescrip)
trailer.extend(pad)
# append signature size as a 4-byte filed in little endian format
sigSize = len(signature)
sigSizeFiled = hex(sigSize)
sigSizeFiled = format32BitHexStr(sigSizeFiled)
sigSizeFiled = toLitteEndianByte(sigSizeFiled)
trailer.extend(sigSizeFiled)
# append signature
if len(signature) > sigFixedSize:
raise Exception(
"Signature size exceeded allowed size! signature size: " +
sigSize + ". Allowed maximum size: " + sigFixedSize)
padSize = sigFixedSize - sigSize
pad = bytearray(padSize)
trailer.extend(signature)
trailer.extend(pad)
return trailer
def addOTADescriptorToImage(inputImagePath, otaDescriptor, outputImagePath):
"""
Add given OTA descriptor into given image
:param inputImagePath:
:param otaDescriptor:
:param outputImagePath:
:return:
"""
with open(inputImagePath, "rb") as fIn:
data = fIn.read()
with open(outputImagePath, "wb") as fOut:
# 1. Add sequence number
sequenceField = toLitteEndianByte(otaDescriptor.sequenceNumber)
fOut.write(sequenceField)
# 2. Add start address
startAddrField = toLitteEndianByte(otaDescriptor.startAddress)
fOut.write(startAddrField)
# 3. Add end address
endAddrField = toLitteEndianByte(otaDescriptor.endAddress)
fOut.write(endAddrField)
# 4. Add execution address
execAddrField = toLitteEndianByte(otaDescriptor.executionAddress)
fOut.write(execAddrField)
# 5. Add hardware ID
HardwareIdField = toLitteEndianByte(otaDescriptor.hardwareID)
fOut.write(HardwareIdField)
# 6. Add reserved bytes
reserveField = toLitteEndianByte(otaDescriptor.reserves)
fOut.write(reserveField)
fOut.write(data)