mirror of
https://github.com/ahezard/twl_firm_patcher.git
synced 2025-06-18 21:35:33 -04:00
120 lines
3.3 KiB
Python
120 lines
3.3 KiB
Python
# -*- coding: utf8 -*-
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# Patch an .nds (works with homebrew and ds demo only) to make it ready for make_cia
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#
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# 2016-02-28, Ahezard
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#
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# inspired by
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# Apache Thunder .nds edited files and comments
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# https://github.com/Relys/Project_CTR/blob/master/makerom/srl.h
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# https://dsibrew.org/wiki/DSi_Cartridge_Header
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# if the header size of the input nds file is 0x200 (homebrew)
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# the header size of the output nds file will be patched to 0x4000 (normal ds/dsi header), 0x3E00 offset
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from struct import *
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from collections import namedtuple
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from collections import OrderedDict
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from pprint import pprint
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import os, sys
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import binascii
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import argparse
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parser = argparse.ArgumentParser(description='create the twl_firm bin from twl_bg.cxi section')
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parser.add_argument('--firm', help='firm file to patch')
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parser.add_argument('--cxi', help='cxi to insert')
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parser.add_argument('--out', help='output firm file')
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args = parser.parse_args()
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#
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# CRC16 MODULE
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#
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# includes CRC16 and CRC16 MODBUS
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#
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from ctypes import c_ushort
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# from https://github.com/cristianav/PyCRC/blob/master/demo.py
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class CRC16(object):
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crc16_tab = []
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# The CRC's are computed using polynomials. Here is the most used
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# coefficient for CRC16
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crc16_constant = 0xA001 # 40961
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def __init__(self, modbus_flag=False):
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# initialize the precalculated tables
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if not len(self.crc16_tab):
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self.init_crc16()
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self.mdflag = bool(modbus_flag)
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def calculate(self, input_data=None):
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try:
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is_string = isinstance(input_data, str)
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is_bytes = isinstance(input_data, (bytes, bytearray))
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if not is_string and not is_bytes:
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raise Exception("Please provide a string or a byte sequence "
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"as argument for calculation.")
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crc_value = 0x0000 if not self.mdflag else 0xffff
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for c in input_data:
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d = ord(c) if is_string else c
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tmp = crc_value ^ d
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rotated = crc_value >> 8
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crc_value = rotated ^ self.crc16_tab[(tmp & 0x00ff)]
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return crc_value
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except Exception as e:
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print("EXCEPTION(calculate): {}".format(e))
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def init_crc16(self):
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"""The algorithm uses tables with precalculated values"""
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for i in range(0, 256):
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crc = c_ushort(i).value
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for j in range(0, 8):
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if crc & 0x0001:
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crc = c_ushort(crc >> 1).value ^ self.crc16_constant
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else:
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crc = c_ushort(crc >> 1).value
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self.crc16_tab.append(crc)
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def getSize(fileobject):
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current = fileobject.tell()
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fileobject.seek(0,2) # move the cursor to the end of the file
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size = fileobject.tell()
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fileobject.seek(current,0)
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return size
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def skipUntilAddress(f_in,f_out, caddr, taddr):
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chunk = f_in.read(taddr-caddr)
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f_out.write(chunk)
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def writeBlankuntilAddress(f_out, caddr, taddr):
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f_out.write("\x00"*(taddr-caddr))
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firm_fname=args.firm
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cxi_fname=args.cxi
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# write the file
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filer = open(firm_fname, 'rb')
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filew = open(args.out, "wb")
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filesize=getSize(filer)
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skipUntilAddress(filer,filew,0,0x200)
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cxi = open(cxi_fname, 'rb')
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cxisize=getSize(cxi)
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data = cxi.read(cxisize)
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cxi.close()
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filew.write(data);
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filer.read(cxisize);
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skipUntilAddress(filer,filew,cxisize+0x200,filesize)
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filew.close()
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filer.close()
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