Save State Editors Programming v2.5

by: The_Fake_God
Last updated: September, 2001

Things you need before starting

A copy of Visual Basic
- http://www.retrobase.com/fakegod/downloads

UgeTab's Save State Hacking Guide (if you don't know how to hack states)
- http://www.angelfire.com/nc/ugetab/

Index

1. Introduction
2. Programming Languages
3. The Basic of Visual Basic
4. Variables
5. File I/O
6. Binary Mode
7. Making the Editor Step by Step
8. Advanced Data Loading/Saving
9. Advanced Editor Creation
10. Links
11. Credits

Introduction

Finally I decided to update this doc. Version 2.5 is a total remake from the last "plain text" version. I added a lot of stuff: basic programming, more techniques, "how to make your editors look nice", advanced controls support, etc. I can guarantee that after reading this document youīll be able to create a full featured Save State Editor. Everything here is fixed to the best of my knowledge and experience with editors. Well, make your best effort and read/analyze every piece of code.

Programming Languages

Thereīs enough material to write entire books about this topic, however you wonīt need a single page of theory to make editors. This section was created to show you the basic structure of a program.

There are three types of programming languges: machine code (hex, binary), Low Level Languages (6502, Z80, 486, etc.), High Level Languages (C++, Pascal, Basic, etc.). What's the difference? Well, I don't if anyone still program in machine code (maybe an old 50's programming enthusiast...) Low Level Languages (well known as Assembly) are used in several systems and programs. I.E a NES rom is coded in 6502, a GB one uses Z80 (well sort of), 486: dos/windows programs(for example). Assembly is the fastest language around. High Level Languages are the ones in which you can make readable codes. I think C++ is the fastest HHL. These languages (HLL) are converted to Assembly through a compiler. Visual Basic is not a full compiled language, that's why itīs sooo slow. Every VB program needs something called Microsoft Visual Basic Virtual Machine (MSVBVMx.DLL). This library is some kind of VB<->System translator.

Itīs important to know at least the basics of the theory, this little lesson about PL, will help you understand your programs.

The Basic of Visual Basic

If you donīt know how to create/save/open projects, I suggest you to learn before continuing. Visual Basic has a collection of objects named Controls. There are a lot of different controls, this is a list of the most common ones:

The Form isnīt a control, itīs a dialog box. Each one of them(controls) is determined by its own characteristics. For example, think of your house as a VB object:

MyHouse.Address

"Address" is a property of your house. Some controls have "mini-controls" inside them:

MyHouse.MyRoom.Size

"MyRoom", subitem. "Size" Subitem's property.

Make a simple program to mess around with object properties. It will help you understand further examples.

Variables

This is one of the most important lessons. Take a look at this chart:

There a few more variable types that youīre not going to use in Save State Editors programming. Remember the size of each one.

File I/O

If you have programmed in other languages you will find big differences when using Basic. In VB, you don't need interrupts or classes. Indeed VB File I/O is pretty straight forward. These are VB I/O Access modes:

Input  - Read only mode (I)
Output - Write only mode (O)
Random - Data types, sized block (youīre not going to use it)
Binary - Read/Write Binary. This is the mode that youīre going to use.

Binary Mode

Binary mode can be called like this:

The "#1" at the end is the file number. It can be any byte value(0/255). A very important thing to remember is to close the file after you used it. Binary mode has two basic methods weīre going to cover:

Get - Syntax is: Get [Filenumber], [Address], [Variable]
Put - Syntax is: Put [Filenumber], [Address], [Variable]

You can call these methods like this:

Dim is a keyword used to "Dimension" a variable to a type. You can change the type to anything (valid!) you want. "Get #1, 123456 + 1, Life" Ok, your program will get 1 byte of data (size of Life) from the offset 123456. The "+ 1" thing is used because a hexeditor (or any other program you use to find offsets), reads starting at offset 0, Visual Basic starts at 1. Itīs better to leave the "123456 + 1" instead of "123457" beacuse itīs easier to debug (but itīs still the same). The Cbyte() function returns a valid size according to the sent variable (CInt() and CLng() are also valid). Now you know enough to create a simple save state editor.

Making the Editor Step by Step

There are some basic steps you must follow in order to make an editor. First of all, you need to get the name of the file youīre going to edit. You can take different paths (API, Simple Dialog with FileBoxes, CommonDialog Control). Iīm going to explain the CommonDilaog control one.

Common Dialog Control

Add the control to your project (CTRL+T). "Microsoft Common Dialog Control x.0" Once you have added it to your main form, make this changes:

.Name        = dlgMain
.Filter      = Zsnes Save States (*.zs*)|*.zs*
.CancelError = True

Now that you have a way to get the file, make it work. Put a CommandButton somewhere in your form.

.Name    = cmdLoad
.Caption = &Load

Open the code editor (double click on cmdLoad) and go to cmdLoad_Click():

Everytime you click on cmdLoad it will open and close the selected file. You need something to edit! Go to the "General" section of your form code and add these lines:

You have the memory, but you still need someplace to display the data. Add three TextBoxes:

Name = txtMoney
Name = txtHp
Name = txtLevel

Change the look of your form:

Now change the cmdLoad_Click() Subroutine:

Test this program with a DeJap's Patched Tales of Phantasia State. Now, lets save the changes. Add a CommadButton with the following properties:

.Name    = cmdSave
.Caption = &Save

Put it somewhere in the form, like this:

Now open up the code editor and make the cmdSave_Click() subroutine look like this:

Since you already got a filename, you donīt need to get it again. Open the same file and "Put" the changed stuff. Use always the TypeCast and Val() functions since you have to size every value to your needs, also the user can type "xlksj" instead of a valid number, and you donīt your program to crash, do you?. If Val() reads an invalid number the returned value will be zero.

I found the offsets using Universal Game Editor (decimal base editor), if you use hexworkshop or anyother hexediting program to find the offsets, you can use the "&H" prefix to use hexadecimal numbers. Examples:

Put #1,  &H320A + 1, MyVariable
Put #1,  &HFFFF + 1, CInt(&HFFFF)  ' CInt(&HFFFF) will return -32767  
Put #1,  &HC04E + &H1, CByte(&HFF) ' Which is actually a bit stupid

Advanced Data Loading/Saving

In the variables lesson you learned the ranges of each data type. A lot of games use different ranges and types of variables. First of all you have to know the difference between a signed variable and an unsigned one.

        Signed         Unsigned
Byte    -127/127       0/255
Integer -32767/32767  0/65535

You canīt read a 65535 directly through VB (at least not as an integer). You have to convert what you have, from signed to unsigned. Use the following functions to convert the values, these functions were written by Che Weng:

Another example is the way Squaresoft games store their money variables. Instead of using 4 bytes to make a long integer they set it to three bytes making 9999999 a reasonable number for your money. I wrote three functions to solve the problem:

Now that you know how to edit those variables, add a bit more functionality to your editors by improving the GUI.

Advanced Editor Creation

The advanced editor creation resides mainly in the GUI (graphical user interface) and the system you use to Load/Data. First Iīm going to discuss the different ways to Load/Data.

The Controls Array

Create a new project and add a Label to it. Now right click on it and select copy, right click on your form and select paste. A message box will pop up asking if you want to create a control array. Click on yes/ok and check the name of your first Label. Label1(0) and the second one: Label1(1). Repeat the operation and VB wonīt ask, it will add a control named Label1(2). The number enclosed in parentheses represents the array index, so if you want to have access to any of the array controls use that number. Now, all the Message Handlers (Click(), MouseUp()...) will have an extra parameter: Index As Integer. This means that youīll recieve the array index. So you can set up If...End If forks like this:

If Index = 0 Then.....
ElseIf Index = 6 Then......
End If

I suggest you to use control arrays when coding RPG's editors. This will make your code faster and more effective.

The For...Next Loop

I guess you already know how to use it, if not this is (briefly) how it works:

For [initialize index] To [Upper Bound] Step #(optional)
.
.
.
Next [index]

Example:

For i = 0 to 1000
Form1.Caption = i
Next i

You can take advantage of this in most RPG games. These games (in their vast majority) store the character's data in a single block of bytes (which size varies depending on the amount of characters). So if the HP is stored in offset 100, the next character's hp is stored in offset 200 and so on you can use something like this:

k = 0
For i = 100 to 600 Step 100 ' Assuming you have to edit 6 chrs
Get #1, i + 1, MyVar
txtHP(k).Text = MyVar
k = k + 1
Next i

The process goes like this, Get the variable a the selected offset and copy it to a control(index) (part of an array). The "i" variable is incremented by 100.

99 of all Items

Use a For...Next Loop to solve the problem (Unless you want to type 99 Put #1.....) Example:

k = 0
For i = 3000 to 3099
Put #1, i + 1, CByte(k)
Next i

Repeat the process for the amount of items and youīre off.

Other methods

These methods are a bit tedious sometimes, when you make large editors the code gets hard to debug. There are more effective ways to Load/Save data. I just developed a new method based on my newly gotten C++ skills :P It allowed me to code the FF3 editor in less than two hours, fast and absolutely no bugs! I will post it on this doc as soon as I get more into it, since itīs really beta (at least in my programs).

Making your program look better

I suggest you to make extensive use of other controls like the tabs, progress bars, image lists, etc. Iīm going to cover only tabs and p. bars.

Tabs

Thereīs not too much to explain. The code I use is the one created by the VB Application Wizard. Open up the "The Eye of The Beholder" code and copy the tbsOptions_Click() and tbsOptions_KeyDown message handlers. The code is based on a control array of picture boxes, used to hold a set of controls. The tabs show/hide the pictures according to the clicked index.

You can add little 16x16 images to the tabs. Make sure that the images are all the same size, also save them as 24-bit bitmaps with the same mask color or the mask color wonīt work. Add an ImageList to your form and add your images to it. Change the mask color to match the one you have. Now in the tabs "Custom" Dialog (properties | custom) set the ImageList to the one you just added. Now you can select the image index on the tabs (individual clickable little tabs) properties sheet.

Progress Bar

I use this control as Life Meter bars. If you have used my Zelda 3 Editor, you might have seen the Magic Meter Editor, it uses a progress bar. These bars make your GUI look better, itīs a more "gaming" touch. Example:

' Add a ProgressBar and name it pbLife
' Add a TextBox and Name it txtLife

Sub txtLife_Change()
If val(txtLife) < 1000 then pbLife.Value = val(txtLife)
End Sub

Thatīs all, every time you change the value in the textbox, your progress bar will be updated too.

More Graphical Tips

Try to use stuff from the game youīre editing (see my FF3 Item Editor). Add little pictures and this related to the game, also pick a good icon (you better rip it out from the game).

Links

• http://www.maxcode.com
  Good site with VB tutorials
  
  
• http://www.freevbcode.com
  Great collection of VB source code
  
  
• http://www.programmersheaven.com
  Wide selection of programming docs and utilities
  
  
• http://www.zophar.net
  So far, the best emulation site
  
  
• http://www.romhacking.org
  Amazing collection of romhacking docs
  
  
• http://www.vbexplorer.com
  Probably the best VB site
  

Credits

Thanks to: Ugetab, Maxim, War Mike(for giving me the excuse I needed to update this doc :D), Che(for teaching me how to do editors), Gil-Galad(for teching me how to decompress Snes9x states), zophar.net.

The_Fake_God - The_Fake_God@hotmail.com
http://www.retrobase.com/fakegod