e893ad24ee
Crash happened when file is mult of 16384, which means last block size is zero and it crashed because of data[-1]
43 lines
1.1 KiB
Python
43 lines
1.1 KiB
Python
# -*- coding: utf-8 -*-
|
|
|
|
class ChkSum:
|
|
|
|
def __init__(self):
|
|
self.chksum = 0
|
|
self.last_byte = 0xff
|
|
|
|
def add(self, data):
|
|
self.chksum += sum(bytearray(data))
|
|
self.last_byte = data[-1]
|
|
self.chksum &= 0xff
|
|
|
|
def add_from_file(self, filename: str, print_progress: bool = False, blocksize: int=16384):
|
|
with open(filename, "rb") as f:
|
|
while True:
|
|
block = f.read(blocksize)
|
|
if len(block) != 0:
|
|
self.add(block)
|
|
if print_progress:
|
|
print(".", end="", flush=True)
|
|
if len(block) < blocksize:
|
|
break
|
|
f.close()
|
|
|
|
def get(self):
|
|
remainder = ( 0x100 - self.chksum ) & 0xff
|
|
return remainder
|
|
|
|
def get_sum(self):
|
|
return self.chksum
|
|
|
|
def is_valid(self):
|
|
return (self.chksum == 0)
|
|
|
|
def get_expected(self):
|
|
chksum_without_last = ( 0x100 + self.chksum - self.last_byte ) & 0xff
|
|
expected = ( 0x100 - chksum_without_last ) & 0xff
|
|
return expected
|
|
|
|
def get_last_byte(self):
|
|
return self.last_byte
|