********************************************************************************
*                 Megami Tensei Gaiden: Last Bible (Game Gear)                 *
*                     English Translation Patch Materials                      *
********************************************************************************

This package contains the source materials (code/art) for the English
translation project for the Game Gear game Megami Tensei Gaiden: Last Bible.
                    
                                IMPORTANT NOTE:
  
  By Tom's request, this project does not include his translated game script. 
The project will not build as-is. You will need to extract the script from the 
patched game binary and regenerate the script files yourself. See the section 
"Extracting the Script" for details.

                    ****************************************
                    *          Build Instructions          *
                    ****************************************
                    
The build system is only set up for Unix-like systems, though none of the code
is fundamentally dependent on this and could be ported with a bit of effort.
You'll need GCC and libpng.

Get a ROM image of the original game. It should match these specifications:

  No-Intro filename: Megami Tensei Gaiden - Last Bible (Japan).gg
  CRC32:             2E4EC17B
  MD5:               AB54600E28D866558323381F74FE2749
  SHA-1:             D98332EBA27FD4A0DB82D551A54BEE4FDCCF41A2

Rename it "lastbible.gg" and place it in the "lastbible" folder. Then:

$ cd lastbible
$ ./build.sh

build.sh should then build all the necessary tools and output the translated
ROM as lastbible_en.gg. Note, again, that the build process will fail unless you 
have extracted the script yourself using the directions in "Extracting the
Script".

If you want to modify the project, check build.sh to see where the resources
that get inserted into the game are coming from.

                    ****************************************
                    *        Extracting the Script         *
                    ****************************************

As noted above, this project does not include the translated game script. Here 
is some information on how you can extract it from the translated ROM. The 
instructions in this guide are written with reference to version 3 of the patch 
(patched ROM MD5 sum: 16879fe9fdff6822dbf48560ca7bf6bb).

First, get the game and apply the English translation patch to it. I've included 
version 3 of the patch in the repository as lastbible/lastbible_patch.ips.

Located in lastbible/script is a mostly-empty folder where the script files need 
to be placed. A small number of files that contained entirely new content have 
been left intact and pre-placed in lastbible/script. lastbible/script_scraped 
contains the remaining script files, but with all content other than script 
directives removed.

Here is a list of files you must regenerate and place in lastbible/script:
  * credits.txt
  * dialogue.txt
  * enemies.txt
  * enemies_plural.txt
  * items.txt
  * menus.txt
  * scroll1.txt
  * scroll2.txt
  * spells.txt

These files fall into three categories, each of which needs to be extracted 
differently.

  ==================
  = Scrolling Text =
  ==================
  
Files:
  * scroll1.txt
  * scroll2.txt
  * credits.txt

These are the source files for the scrolling text sequences at the start and end 
of the game. Unlike the original game, the translation does not store them as 
text -- they are rendered to graphics during the build process, which means they 
can't easily be extracted like other material. The easiest thing to do is 
probably just to copy them by eye. For these files only, each line of text must 
be followed by an #ENDMSG directive.

  ===============
  = Tabled Text =
  ===============
  
Files:
  * enemies.txt        -- ROM offset 0xaeb10, 115 entries
  * enemies_plural.txt -- ROM offset 0xaef39, 115 entries

These script files are stored in the translated ROM using offset tables -- one 
16-bit offset from the base address of the table per string. To regenerate them, 
extract each table entry using lastbible/table/lastbible_vwf_en.tbl and wrap the 
content with the #STARTMSG and #ENDMSG directives.

  =================
  = Remapped Text =
  =================
  
Files:
  * dialogue.txt
  * items.txt
  * menus.txt
  * spells.txt

These script files are stored in the game using a universal hash table that 
remaps the original Japanese string pointers to the corresponding English ones. 
Here is how it is used:

  1. Given the address of a string from the Japanese version of the game, AND it 
with 0x0FFF, then multiply by 4. As an example, suppose there is a string at 
0x6C038 in the Japanese game; the corresponding value is 0xE0.
  
  2. ROM 0x80000 contains the bucket list pointers for the hash table. Take the 
value from Step 1 and add it to 0x80000 to get the address of the bucket list 
infostruct (0x800E0 in our example).
  
  3. The address you derived in Step 2 points to a struct that gives the 
position of a list of hash buckets. The format is:
     * 1b bank number
     * 2b slot2 pointer
     * 1b dummy
     
     If the bank number is 0xFF, then the bucket list for that hash key is empty 
(and whatever string you are attempting to find does not exist).
     
  4. Convert the bucket list information to an absolute ROM address: ((banknum * 
0x4000) + (slot2ptr - 0x8000)). This yields the ROM address of the actual bucket 
list.
     
     For our example, suppose the banknum is 0x21 and the pointer is 0x807C; the 
bucket list is thus located at 0x8407C.
     
  5. The address from Step 4 consists of a series of hash buckets of the 
following format:
     * 1b bank number of original Japanese string
     * 2b pointer to original Japanese string (using the original slotting 
information, so 0x0000-0x3FFF for slot 0 pointers, etc.)
     * 1b bank number of new English string
     * 2b slot2 pointer to new English string
     
     If the bank number is 0xFF, you've reached the end of the bucket list.
     
  6. Take the Japanese string address you started out with in Step 1 and convert 
it to SMS bank/pointer format using the original slot information. Supposing our 
string at 0x6C038 is accessed through slot2, its pointer is 0x8038 and its slot 
is 0x1B. Then, simply scan through the bucket list until you find an entry with 
a matching bank/pointer.
  
  7. Having found the matching Japanese string, simply convert the corresponding 
English pointer to an absolute ROM address. In the given example, we find that 
our target string is located at 2F:9864, or ROM 0xBD864.

To regenerate the remapped script files, you need to write a program that does 
the following:

  1. Scan each line of the scraped script file for directives (lines beginning 
with '#').
  
  2. Copy all directives other than #STARTMSG directly to the output file.
  
  3. For #STARTMSG directives, parse the following three fields from the 
directive:
     * Parameter 1: original string offset
     * Parameter 2: original string length
     * Parameter 3: original string slot number (0, 1, or 2)
     
     For the previous example, the #STARTMSG directive looks like this:
     #STARTMSG(0x6C038, 14, 2)
     
  4. Do the hash lookup from the ROM as previously described in order to get the 
address of the corresponding translated string.
  
  5. Extract the English string using the table file in 
lastbible/table/lastbible_vwf_en.tbl. 0xFF is the string terminator.
  
  6. Output the #STARTMSG directive, then the translated string.
  
This should yield a full script file that you can copy over the "scraped" file.

If you also want the original Japanese strings, use 
lastbible/table/lastbible.tbl to read from the old string address. You may find 
it helpful to consult lastbible/src/lastbible_scriptdmp.cpp, the original script 
dumping program.

Note that the script directives also set up the automatic line wrapping 
performed when the script is compiled, but the extracted script will have 
built-in hard linebreaks that override it. You'll want to remove those so the 
line wrapper can do its job.

                    ****************************************
                    *              Licensing               *
                    ****************************************

See COPYING. Basically, everything by me (Supper) is GPLv3, and everything else
is under the terms of whoever wrote it.

                    ****************************************
                    *               Credits                *
                    ****************************************

                                  Tom -- Translation
                               Supper -- Hacking