prepend-xci-key-area.py

prepend-xci-key-area.py

from sys import argv, exit
from os import path

input_rom_file_path = argv[1]
input_keyarea_file_path = argv[2]
output_rom_file_path = argv[3]

input_keyarea_size = path.getsize(input_keyarea_file_path)
target_size = 0x1000
padding = bytearray.fromhex('00')

with open (input_keyarea_file_path, 'rb') as keyarea_file:
    if input_keyarea_size == target_size:
        keyarea_data = keyarea_file.read()
    elif input_keyarea_size < target_size:
        keyarea_data = keyarea_file.read() + padding * (target_size - input_keyarea_size)
    elif input_keyarea_size > target_size:
        exit('Key area data bigger than 0x{}.'.format(str(target_size)))
        
with open(input_rom_file_path, 'rb') as input_rom_file, open(output_rom_file_path, 'wb') as output_rom_file:
    output_rom_file.write(keyarea_data)
    for chunk in iter(lambda: input_rom_file.read(1024), b""):
        output_rom_file.write(chunk)