kd20_uboot.py

gistfile1.txt

#!/usr/bin/env python2
import sys
import struct
from binascii import crc32

def unwrap(data):
    b = 0
    out = ''

    for i in range(len(data)):
        shift = (i % 8)

        if data[i] not in ('\x55', '\xaa'):
            break

        bit = data[i] == '\x55'

        b |= (bit << shift)

        if shift == 7:
            out += chr(b)
            b = 0

    return out

def wrap(data):
    out = ''

    for b in data:
        for i in range(8):
            if (ord(b) >> i) & 1:
                out += '\x55'
            else:
                out += '\xaa'

    return out

def recrc(data):
    size, crc = struct.unpack('II', data[:8])
    data = data[8:]
    calc_crc = crc32(data) & 0xffffffff

    assert len(data) == size, 'invalid length'
    #assert calc_crc == crc, 'bad crc'

    hdr = struct.pack('II', size, calc_crc)
    return hdr + data

def fix(data):
    data = data.replace('loadr=nand  read.e 0x62000000 240000 280000', 'loadr=nand  read.e 0x62000000 240000 600000')
    data = data.replace('load=nand  read.e 0x60500000 840000 300000',  'load=nand  read.e 0x60500000 840000 7c0000')
    return data

fp = open(sys.argv[1])
data = fp.read()
rdata = None

orig_len = len(data)

data = unwrap(data)
data = fix(data)
data = recrc(data)
data = wrap(data)

open('uboot_patched.bin','wb').write(data)

data = data.ljust(orig_len, '\xff')
open('uboot_patched_padded.bin','wb').write(data)