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import struct
import sys
chunk_lengths = [0,0,0,6,2,5,12,5,3,1,2,5,5,5,1,13,13]
bytewises = []
bytewise_results = []
wordwises = []
wordwise_results = []
crcs = []
crc_results = []
data = ""
with open(sys.argv[1], 'rb') as f:
data = f.read()
f.closed
base_address = struct.unpack('<I', data[1:5])[0]
i = 0x11 # first chunk location
while i < len(data):
chunk_type = ord(data[i])
if chunk_type == 0x02: # END_OF_CHUNKS
break
elif chunk_type == 0x07: # CUSTOM_BERRY
start_address = struct.unpack('<I', data[i+1:i+5])[0] - base_address
bytewises.append([start_address + 0x52C, start_address, start_address + 0x52C])
elif chunk_type == 0x0D: # BATTLE_TRAINER
start_address = struct.unpack('<I', data[i+1:i+5])[0] - base_address
wordwises.append([start_address + 0xB8, start_address, start_address + 0xB8])
elif chunk_type == 0x0F: # CHECKSUM_BYTES
start_address = struct.unpack('<I', data[i+5:i+9])[0] - base_address
end_address = struct.unpack('<I', data[i+9:i+13])[0] - base_address
bytewise.append([i + 1, start_address, end_address])
elif chunk_type == 0x10: # CHECKSUM_CRC
start_address = struct.unpack('<I', data[i+5:i+9])[0] - base_address
end_address = struct.unpack('<I', data[i+9:i+13])[0] - base_address
crcs.append([i + 1, start_address, end_address])
elif chunk_type < 0x02 or chunk_type > 0x10:
print "Unknown chunk {0:X}".format(chunk_type)
raise TypeError
i += chunk_lengths[chunk_type]
# calculate and insert all wordwise checksums
for wordwise in wordwises:
sum = 0
for i in range(wordwise[1], wordwise[2], 4):
sum = (sum + struct.unpack('<I', data[i:i+4])[0]) & 0xFFFFFFFF
wordwise_results.append(sum)
i = 0
for wordwise in wordwises:
data = data[0:wordwise[0]] + struct.pack('<I', wordwise_results[i]) + data[(wordwise[0] + 4):]
i += 1
# calculate and insert all bytewise checksums
for bytewise in bytewises:
sum = 0
for i in range(bytewise[1], bytewise[2]):
sum = (sum + ord(data[i])) & 0xFFFFFFFF
bytewise_results.append(sum)
i = 0
for bytewise in bytewises:
data = data[0:bytewise[0]] + struct.pack('<I', bytewise_results[i]) + data[(bytewise[0] + 4):]
i += 1
# calculate and insert all CRC checksums
for crc in crcs:
sum = 0x1121
for i in range(crc[1], crc[2]):
sum ^= ord(data[i])
for j in range(8):
if(sum & 1):
sum = (sum >> 1) ^ 0x8408
else:
sum >>= 1
sum = ~sum & 0xFFFF
crc_results.append(sum)
i = 0
for crc in crcs:
data = data[0:crc[0]] + struct.pack('<I', crc_results[i]) + data[(crc[0] + 4):]
i += 1
# write the updated file
out = open(sys.argv[2], 'w')
out.write(data)
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