#           m:robe 500i image updater script - Ver 0.95 BETA
# -------------------------------------------------------------------
# Created by: shirour                                        29/04/06
# Usage:
#
#   DISCLAIMER: USE THIS SCRIPT AT YOUR OWN RISK!
#    
# DecryptFile(inputfile,outputfile)
#    default inputfile  = "N5002-BD.BIN"
#    default outputfile = "N5002-BD.DEC"
#
#   Decrypts the original firmware file (inverse it and reorder the bits)
#
# CorrectCRC(inputfile,outputfile):
#
#   default inputfile  = "N5002-BD.DEC"
#   default outputfile = "N5002-BD.DEC"
#
#   Updates the CRC according to the updated _DECRYPTED_(!) file.
#
# EncryptFile(inputfile,outputfile)
#    default inputfile  = "N5002-BD.BIN"
#    default outputfile = "N5002-BD.DEC"
#
#   Encrypts the updated firmware file (inverse it and reorder the bits)
#
# GetImage(imagenum,inputfile,offset):
#   default inputfile = "N5002-BD.DEC"
#   default offset = 0x100000-0x18        DO NOT CHANGE THIS VALUE!
#
#   Reads the $imagenum$ (a number 0-389) from the decrypted
#   firmware and saves it to a file named "imagenum.ext"
#   (where the extension comes from the file type.
#
# UpdateImage(imagenum,imagefile,inputfile,outputfile,offset=0x100000-0x18):
#   default inputfile = "N5002-BD.DEC"
#   default outputfile = "N5002-BD.DEC"
#   default offset = 0x100000-0x18        DO NOT CHANGE THIS VALUE!
#
#   Updates the $imagenum$ image to $imagefile$.
#
#   Normal usage scenario:
#   put N5002-BD.BIN in the same directory as the script file.
#   run DecryptFile()
#   run GetImage(0)   where here you can choose whatever image number you
#            want, and do that as many times as you'd like...
#            change the images, as long as their sizes don't grow.
#   run CorrectCRC()
#   run EncryptFile()
#
#       have fun.
#
#

import binascii;
import array;

dec_dic = {
    0:3,
    1:2,
    2:1,
    3:0,
    4:5,
    5:6,
    6:4,
    7:7,
    8:9,
    9:11,
    10:8,
    11:10,
    12:14,
    13:12,
    14:15,
    15:13,
    };

enc_dic = {}
for i in dec_dic:
    enc_dic[dec_dic[i]] = i;
   
image_type_dic = {
    '0x3E8L':'jpg',
    '0x3E9L':'png',
    };

def DecryptFile(inputfile="N5002-BD.BIN",outputfile="N5002-BD.DEC"):
    ModifyFile(inputfile,outputfile,dec_dic);

def EncryptFile(inputfile="N5002-BD.DEC",outputfile="N5002-BD-NEW.BIN"):
    ModifyFile(inputfile,outputfile,enc_dic);
   
def CorrectCRC(inputfile="N5002-BD.DEC",outputfile="N5002-BD.DEC"):
    print "Opening file", inputfile;
    inpfile = file(inputfile,"r+b",1000);
    filearr = array.array('L', inpfile.read()).tolist()   # make integer list       

    print "Computing the CRC..."    #Note - the real file begins at 0x18 -> +5
    CRC = reduce(lambda x,y:x+filearr[y+5],range(0,len(filearr)-5-1));
    CRC = hex(CRC)[-9:-1];
    print "The updated CRC value is:", CRC
    inpfile.seek(0,0);
    filearr = inpfile.read();
   
    inpfile.close;
    del inpfile;
   
    print "Writing CRC to the file",outputfile
   
    outfile = file(outputfile,"w+b",1000);     
   
    filearr=filearr[:-4];
    for i in map(lambda x: dec_dic.get(x)-12,range(12,16)):
        filearr = filearr+ chr(eval('0x'+CRC[2*i]+CRC[2*i+1]) ^ 0xFF);

    outfile.write(filearr);
    filearr = "";
   
    outfile.close;
    del outfile;
    print "Done."
    return CRC;

def ModifyFile(inputfile,outputfile,thedic):
    print "Opening file", inputfile;
    inpfile = file(inputfile,"r+b",1000);
    filearr = array.array('B', inpfile.read()).tolist()   # make integer list       
    tmplist = (len(filearr)/16+1)*range(0,16);

    print "Reordering the file..."
    filearr = map(lambda x:filearr[thedic[tmplist[x]]+(x/16)*16]^0xFF,range(0,len(filearr)));

    print "Making output file",outputfile
    outfile = file(outputfile,"w+b",1000);   
    filearr = map(lambda x:chr(x),filearr);
    filearr = "".join(filearr);
    outfile.write(filearr);

    outfile.close;
    inpfile.close;
     
    tmplist = "";
    print "Done."
    return filearr;


def GetImage(imagenum,inputfile="N5002-BD.DEC",offset=0x100000-0x18):
    if (imagenum > 389) or (imagenum <0> 389) or (imagenum < 0):
        print "Wrong image number (0-389)";
        return -1;
    print "Reading input image file:",imagefile;
    imgfile = file(imagefile,"r+b",1000);
    imagestr = imgfile.read();
    imgfile.close();
    print "Reading input file:",inputfile;
    inpfile = file(inputfile,"r+b",1000);
    print "Extracting image details...";
    adr_table = 0x50d84c;
    inpfile.seek(adr_table+(imagenum)*4)
    image_adr = array.array('L', inpfile.read(4)).tolist()[0];
    inpfile.seek(image_adr-offset,0);
    image_type = image_type_dic[hex(array.array('L', inpfile.read(8)).tolist()[0])];
    image_max_size = array.array('L', inpfile.read(4)).tolist()[0];
    image_adr = array.array('L', inpfile.read(4)).tolist()[0] - offset;
    print "Checking image...";
    if image_max_size < len(imagestr):
        print "max image size:",image_max_size;
        return -1;
    imagestr = imagestr + (image_max_size-len(imagestr))*'\x00';    # add 00 if needed
    inpfile.seek(0,0);
    first_part = inpfile.read(image_adr);
    inpfile.seek(image_adr+image_max_size,0);
    second_part = inpfile.read();
    final_file = first_part+imagestr+second_part;
    inpfile.close();
    print "Writing image file."
    outfile = file(outputfile,"w+b",1000);   
    outfile.write(final_file);
    outfile.close;
    print "Done."
    return image_adr;