ckcc-protocol/ckcc/utils.py
2018-06-27 14:15:28 -04:00

49 lines
1.6 KiB
Python

import struct
from collections import namedtuple
def dfu_parse(fd):
# do just a little parsing of DFU headers, to find start/length of main binary
# - not trying to support anything but what ../stm32/Makefile will generate
# - see external/micropython/tools/pydfu.py for details
# - works sequentially only
fd.seek(0)
def consume(xfd, tname, fmt, names):
# Parses the struct defined by `fmt` from `data`, stores the parsed fields
# into a named tuple using `names`. Returns the named tuple.
size = struct.calcsize(fmt)
here = xfd.read(size)
ty = namedtuple(tname, names.split())
values = struct.unpack(fmt, here)
return ty(*values)
dfu_prefix = consume(fd, 'DFU', '<5sBIB', 'signature version size targets')
#print('dfu: ' + repr(dfu_prefix))
assert dfu_prefix.signature == b'DfuSe', "Not a DFU file (bad magic)"
for idx in range(dfu_prefix.targets):
prefix = consume(fd, 'Target', '<6sBI255s2I',
'signature altsetting named name size elements')
#print("target%d: %r" % (idx, prefix))
for ei in range(prefix.elements):
# Decode target prefix
# < little endian
# I uint32_t element address
# I uint32_t element size
elem = consume(fd, 'Element', '<2I', 'addr size')
#print("target%d: %r" % (ei, elem))
# assume bootloader at least 32k, and targeting flash.
assert elem.addr >= 0x8008000, "Bad address?"
yield fd.tell()
yield elem.size
# EOF