#!/usr/bin/python3
from sys import platform
from os import path
from struct import unpack, pack
import sys
import binascii

d2sfile = '/home/xubuntu/.wine/drive_c/Program Files (x86)/Diablo II/Save/my_d.d2s'
if platform != 'linux':
  d2sfile = 'C:\\Users\\user1\\AppData\\Local\\VirtualStore\\Program Files (x86)\\Diablo II\\Save\\my_d.d2s'
if not path.isfile(d2sfile):
  print("your d2s file does not exist.")
  exit(1)
all = ''
try:
  myfile = open(d2sfile, mode='rb')
  all = myfile.read()
  myfile.close()
except:
  print(sys.exc_info()[0])
  exit(2)
#print(len(all))
c = 0
for addr in range(len(all)):
  ct = ord(all[addr:addr+1])
  ct += c >> 31 & 1
  add = 0
  if (addr >> 2) != 3:
    add = ct
  c = add + (c << 1)

"""
if c > 2147483647:
  c = c & 2147483647
if c < -2147483648:
  c = c * -1
  c = c & 2147483647
  c = c * -1
"""
#print(binascii.hexlify(pack('i', c)))
#c=255
c = (c & 0xff000000) >> 24 | (c & 0xff0000) >> 8 | (c & 0xff00) << 8 | (c & 0xff) << 24
chksum = '{0:08X}'.format(c)
print('Checksum:', chksum)
#print(backwards_chksum)
#print('Checksum:', backwards_chksum[6:8] + backwards_chksum[4:6] + backwards_chksum[2:4] + backwards_chksum[0:2])
#print(ord(all[37:38]))
#myfile.seek(37)
#out = myfile.read(1)
#print(unpack('I', out))
#print(ord(out))