Writting to Bytes

Hi all Java Minds......
In my project, am in need to write bytes as follows. For eg,. if we take Credit card, the card number should have card id with 16 bytes.
The card id was splitted as
Card Type - 2 Bytes
Version - 2 Bytes
Unique ID - 4 Bytes
Card Flag - 1 Byte
Card Specific Type - 2 Bytes
Reserved for others - 5 Bytes.
So I need to create 16 Bytes Card ID with this specification. How can this should be? I'm new to this. Please help me. If any one know, please let me know the way and sample source.
Thanks & Regards,
Sakthivel Thangasamy
[email protected]

Hi Friend
You can make a data Structure for your cardID
I am giving you two examples
check if anyone can help you otherwise gaive a bried what kind of values you are expecting to put init
class cardID implements Serializable
          byte cardtype[]=new byte[2];
          byte version[]=new byte[2];
          byte uniqueID[]=new byte[4];
          byte cardFlag[]=new byte[1];
          byte cardSpecificType[]=new byte[2];
          byte reservedForOthers[]=new byte[5];
          public byte[] getCardFlag() {
               return cardFlag;
          public void setCardFlag(byte[] cardFlag) {
               this.cardFlag = cardFlag;
          public byte[] getCardSpecificType() {
               return cardSpecificType;
          public void setCardSpecificType(byte[] cardSpecificType) {
               this.cardSpecificType = cardSpecificType;
          public byte[] getCardtype() {
               return cardtype;
          public void setCardtype(byte[] cardtype) {
               this.cardtype = cardtype;
          public byte[] getReservedForOthers() {
               return reservedForOthers;
          public void setReservedForOthers(byte[] reservedForOthers) {
               this.reservedForOthers = reservedForOthers;
          public byte[] getUniqueID() {
               return uniqueID;
          public void setUniqueID(byte[] uniqueID) {
               this.uniqueID = uniqueID;
          public byte[] getVersion() {
               return version;
          public void setVersion(byte[] version) {
               this.version = version;
     class cardID1 implements Serializable
          char cardtype;
          char version;
          int uniqueID;
          byte cardFlag;
          char cardSpecificType;
          byte reservedForOthers[]=new byte[5];
          public byte getCardFlag() {
               return cardFlag;
          public void setCardFlag(byte cardFlag) {
               this.cardFlag = cardFlag;
          public char getCardSpecificType() {
               return cardSpecificType;
          public void setCardSpecificType(char cardSpecificType) {
               this.cardSpecificType = cardSpecificType;
          public char getCardtype() {
               return cardtype;
          public void setCardtype(char cardtype) {
               this.cardtype = cardtype;
          public byte[] getReservedForOthers() {
               return reservedForOthers;
          public void setReservedForOthers(byte[] reservedForOthers) {
               this.reservedForOthers = reservedForOthers;
          public int getUniqueID() {
               return uniqueID;
          public void setUniqueID(int uniqueID) {
               this.uniqueID = uniqueID;
          public char getVersion() {
               return version;
          public void setVersion(char version) {
               this.version = version;
     }both the above classes have a memory capacity of 16 bytes as you are expecting and can be wriiten as object to file or String etc

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import java.io.File;
import java.io.FileInputStream;
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        return written.getValue();
    public static Pointer openProcess(int permissions, int pid) {
        Pointer process = kernel32.OpenProcess(permissions, true, pid);
        return process;
    public static int getProcessId(String window) {
        IntByReference pid = new IntByReference(0);
        user32.GetWindowThreadProcessId(user32.FindWindowA(null, window), pid);
        return pid.getValue();
    public static Memory readMemory(Pointer process, int address, int bytesToRead) {
        IntByReference read = new IntByReference(0);
        Memory output = new Memory(bytesToRead);
        kernel32.ReadProcessMemory(process, address, output, bytesToRead, read);
        return output;
package com.br.HM;
import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;
import com.sun.jna.platform.win32.WinDef.RECT;
import com.sun.jna.ptr.ByteByReference;
import com.sun.jna.ptr.IntByReference;
import com.sun.jna.win32.StdCallLibrary.StdCallCallback;
import com.sun.jna.win32.W32APIOptions;
* Provides access to the w32 user32 library. Incomplete implementation to
* support demos.
* @author Todd Fast, [email protected]
* @author [email protected]
public interface User32 extends W32APIOptions {
    User32 INSTANCE = (User32) Native.loadLibrary("user32", User32.class, DEFAULT_OPTIONS);
    Pointer GetDC(Pointer hWnd);
    int ReleaseDC(Pointer hWnd, Pointer hDC);
    int FLASHW_STOP = 0;
    int FLASHW_CAPTION = 1;
    int FLASHW_TRAY = 2;
    int FLASHW_ALL = (FLASHW_CAPTION | FLASHW_TRAY);
    int FLASHW_TIMER = 4;
    int FLASHW_TIMERNOFG = 12;
    public static class FLASHWINFO extends Structure {
        public int cbSize;
        public Pointer hWnd;
        public int dwFlags;
        public int uCount;
        public int dwTimeout;
    int IMAGE_BITMAP = 0;
    int IMAGE_ICON = 1;
    int IMAGE_CURSOR = 2;
    int IMAGE_ENHMETAFILE = 3;
    int LR_DEFAULTCOLOR = 0x0000;
    int LR_MONOCHROME = 0x0001;
    int LR_COLOR = 0x0002;
    int LR_COPYRETURNORG = 0x0004;
    int LR_COPYDELETEORG = 0x0008;
    int LR_LOADFROMFILE = 0x0010;
    int LR_LOADTRANSPARENT = 0x0020;
    int LR_DEFAULTSIZE = 0x0040;
    int LR_VGACOLOR = 0x0080;
    int LR_LOADMAP3DCOLORS = 0x1000;
    int LR_CREATEDIBSECTION = 0x2000;
    int LR_COPYFROMRESOURCE = 0x4000;
    int LR_SHARED = 0x8000;
    Pointer FindWindowA(String winClass, String title);
    int GetClassName(Pointer hWnd, byte[] lpClassName, int nMaxCount);
    public static class GUITHREADINFO extends Structure {
        public int cbSize = size();
        public int flags;
        Pointer hwndActive;
        Pointer hwndFocus;
        Pointer hwndCapture;
        Pointer hwndMenuOwner;
        Pointer hwndMoveSize;
        Pointer hwndCaret;
        RECT rcCaret;
    boolean GetGUIThreadInfo(int idThread, GUITHREADINFO lpgui);
    public static class WINDOWINFO extends Structure {
        public int cbSize = size();
        public RECT rcWindow;
        public RECT rcClient;
        public int dwStyle;
        public int dwExStyle;
        public int dwWindowStatus;
        public int cxWindowBorders;
        public int cyWindowBorders;
        public short atomWindowType;
        public short wCreatorVersion;
    boolean GetWindowInfo(Pointer hWnd, WINDOWINFO pwi);
    boolean GetWindowRect(Pointer hWnd, RECT rect);
    int GetWindowText(Pointer hWnd, byte[] lpString, int nMaxCount);
    int GetWindowTextLength(Pointer hWnd);
    int GetWindowModuleFileName(Pointer hWnd, byte[] lpszFileName, int cchFileNameMax);
    int GetWindowThreadProcessId(Pointer hWnd, IntByReference lpdwProcessId);
    interface WNDENUMPROC extends StdCallCallback {
         * Return whether to continue enumeration.
        boolean callback(Pointer hWnd, Pointer data);
    boolean EnumWindows(WNDENUMPROC lpEnumFunc, Pointer data);
    boolean EnumThreadWindows(int dwThreadId, WNDENUMPROC lpEnumFunc, Pointer data);
    boolean FlashWindowEx(FLASHWINFO info);
    Pointer LoadIcon(Pointer hInstance, String iconName);
    Pointer LoadImage(Pointer hinst, // handle to instance
            String name, // image to load
            int type, // image type
            int xDesired, // desired width
            int yDesired, // desired height
            int load // load options
    boolean DestroyIcon(Pointer hicon);
    int GWL_EXSTYLE = -20;
    int GWL_STYLE = -16;
    int GWL_WNDPROC = -4;
    int GWL_HINSTANCE = -6;
    int GWL_ID = -12;
    int GWL_USERDATA = -21;
    int DWL_DLGPROC = 4;
    int DWL_MSGRESULT = 0;
    int DWL_USER = 8;
    int WS_EX_COMPOSITED = 0x20000000;
    int WS_EX_LAYERED = 0x80000;
    int WS_EX_TRANSPARENT = 32;
    int GetWindowLong(Pointer hWnd, int nIndex);
    int SetWindowLong(Pointer hWnd, int nIndex, int dwNewLong);
    int LWA_COLORKEY = 1;
    int LWA_ALPHA = 2;
    int ULW_COLORKEY = 1;
    int ULW_ALPHA = 2;
    int ULW_OPAQUE = 4;
    boolean SetLayeredWindowAttributes(Pointer hwnd, int crKey,
            byte bAlpha, int dwFlags);
    boolean GetLayeredWindowAttributes(Pointer hwnd,
            IntByReference pcrKey,
            ByteByReference pbAlpha,
            IntByReference pdwFlags);
     * Defines the x- and y-coordinates of a point.
    public static class POINT extends Structure {
        public int x, y;
     * Specifies the width and height of a rectangle.
    public static class SIZE extends Structure {
        public int cx, cy;
    int AC_SRC_OVER = 0x00;
    int AC_SRC_ALPHA = 0x01;
    int AC_SRC_NO_PREMULT_ALPHA = 0x01;
    int AC_SRC_NO_ALPHA = 0x02;
    public static class BLENDFUNCTION extends Structure {
        public byte BlendOp = AC_SRC_OVER; // only valid value
        public byte BlendFlags = 0; // only valid value
        public byte SourceConstantAlpha;
        public byte AlphaFormat;
    boolean UpdateLayeredWindow(Pointer hwnd, Pointer hdcDst,
            POINT pptDst, SIZE psize,
            Pointer hdcSrc, POINT pptSrc, int crKey,
            BLENDFUNCTION pblend, int dwFlags);
    int SetWindowRgn(Pointer hWnd, Pointer hRgn, boolean bRedraw);
    int VK_SHIFT = 16;
    int VK_LSHIFT = 0xA0;
    int VK_RSHIFT = 0xA1;
    int VK_CONTROL = 17;
    int VK_LCONTROL = 0xA2;
    int VK_RCONTROL = 0xA3;
    int VK_MENU = 18;
    int VK_LMENU = 0xA4;
    int VK_RMENU = 0xA5;
    boolean GetKeyboardState(byte[] state);
    short GetAsyncKeyState(int vKey);
package com.br.kernel;
import com.sun.jna.*;
import com.sun.jna.win32.StdCallLibrary;
import com.sun.jna.ptr.IntByReference;
// by deject3d
public interface Kernel32 extends StdCallLibrary
    // description from msdn
    //BOOL WINAPI WriteProcessMemory(
    //__in   HANDLE hProcess,
    //__in   LPVOID lpBaseAddress,
    //__in   LPCVOID lpBuffer,
    //__in   SIZE_T nSize,
    //__out SIZE_T *lpNumberOfBytesWritten
    boolean WriteProcessMemory(Pointer p, int address, Pointer buffer, int size, IntByReference written);
    //BOOL WINAPI ReadProcessMemory(
    //          __in   HANDLE hProcess,
    //          __in   LPCVOID lpBaseAddress,
    //          __out LPVOID lpBuffer,
    //          __in   SIZE_T nSize,
    //          __out SIZE_T *lpNumberOfBytesRead
    boolean ReadProcessMemory(Pointer hProcess, int inBaseAddress, Pointer outputBuffer, int nSize, IntByReference outNumberOfBytesRead);
    //HANDLE WINAPI OpenProcess(
    // __in DWORD dwDesiredAccess,
    // __in BOOL bInheritHandle,
    // __in DWORD dwProcessId
    Pointer OpenProcess(int desired, boolean inherit, int pid);
    /* derp */
    int GetLastError();
http://pastebin.com/Vq8wfy39

Hello there,
this tutorial was exactly what I needed, so thank you.
Your problem seems to be in this line:
int writeMemory = writeMemory(writeprocess, address, new short[0x22222222]);
The problem is, you're creating a new short array with the length of 0x22222222. Which not only results in an java.lang.OutOfMemoryError: Java heap space
but also, if it would work, would create an empty array with the length of 0x22222222.
I think you want to write 0x22222222 as value in your address.
Correctly stored the code you'd need to write would be:
short[] sarray = new short[]{(short) 0x22222222};
But because the value is too long for the short, the value stored in your array would be the number 8738.
I think, what you want to do is to store the number 572662306, which would be the hex value, stored in an int variable.
So first of all you need to strip down your hex-value to shorts:
Short in Java uses 16 Bit = 2 Byte. 0x22222222 -> 0x2222 for your high byte and 0x2222 for your low byte
So your array would be
short[] sarray = new short[]{0x2222,0x2222};//notice, that sarray[0] is the lowbyte and sarray[1] the high byte, if you want to store 20 it would be new short[]{20,0} or if you use hex new short[]{0x14,0x00}
The next part is your writeToMemory Method. If I'm right, the method in the tutorial is a little bit wrong. The right version should be this:
public static int writeMemory(Pointer process, int address, short[] data) {
IntByReference written = new IntByReference(0);
int size = data.length*Short.SIZE/8;
Memory toWrite = new Memory(size);
for (int i = 0; i < data.length; i++) {
toWrite.setShort(i*Short.SIZE/8,
data[i]);
boolean b = kernel32.WriteProcessMemory(process, address, toWrite,
size, written);
return written.getValue();
You need to calculate your offset right. And the size of your memory. Maybe you could write this method not with shorts, but with integers. But this should work.
If you pass your new array to this function, it should write 0x22222222 to your adress. If you read out your toWrite value with toWrite.getInt(0) you get the right value.
And there is one more thing. In order to write data to a process, you need to grant two access rights:
A handle to the process memory to be modified. The handle must have PROCESS_VM_WRITE and PROCESS_VM_OPERATION access to the process.
You have to grant the right to write data: PROCESS_VM_WRITE: 0x0020 and PROCESS_VM_OPERATION: 0x0008
So your writeProcess needs to get initialized this way:
Pointer writeprocess = openProcess(0x0020|0x0008,pid);
I hope this works for you. Let me know.
Greetings
Edit:
Because every data you write will be 1 byte to whatever count of byte I think the best way is to use the following method to write data to the memory:
public static void writeMemory(Pointer process, long address, byte[] data)
int size = data.length;
Memory toWrite = new Memory(size);
for(int i = 0; i < size; i++)
toWrite.setByte(i, data[i]);
boolean b = kernel32.WriteProcessMemory(process, address, toWrite, size, null);
You can see some changes. First I changed all address values from int to long, because some addresses are out of range. And with all, i mean all. Not only in writeMemory, but also in readMemory and in your kernel32 Class.
Second I don't use the IntByReference anymore..
To use this method you need to store your data the following way if you would write 4 Byte data:
byte[] values = new byte[]{0x14,0x00,0x00,0x00};
This value would be the number 20. Index 0 will be the lowest byte and index 3 will be the highest byte.
And one more thing I wrote is an method which you can use to calculate your address if you have a baseAddress.
If you restart your program/game your old addresses won't point at the same values of your game. With some research (I use CheatEngine) you can get the baseaddress. This one will alway be the same.
To get from your baseaddress to the dynamic adress you use offsets.
public static long findDynAddy(Pointer process, int[] offsets, long baseAddress)
long pointer = baseAddress;
int size = 4;
Memory pTemp = new Memory(size);
long pointerAddress = 0;
for(int i = 0; i < offsets.length; i++)
if(i == 0)
kernel32.ReadProcessMemory(process, pointer, pTemp, size, null);
pointerAddress = ((pTemp.getInt(0)+offsets[i]));
if(i != offsets.length-1)
kernel32.ReadProcessMemory(process, pointerAddress, pTemp, size, null);
return pointerAddress;
This methods gets a process, an array of offsets (hex-values) and your baseadress and returns the dynamic address.
For Solitaire the following code would give you the address to the score:
long baseAddr = 0x10002AFA8L;
int[] offsets = new int[]{0x50,0x14};
long addr = findDynAddy(process, offsets, baseAddr);
If somebody wants to get the whole code (user32, kernel32 and the cheater) just pm me and I will give you a link.

Write data to serial port every two minutes

Hi,
I use VISA-Write to write data to serial port. I want to write a byte every two minutes. What should I do?
Thanks!

hengfo,
that question is not connected to LV nor to VISA. Its more a systematic question....
So let's view at this a bit more abstract:
You want to "toogle" between two different messages sent to your interface. So you have to know:
- What was the last state i sent?
- When do i have top send the new state?
Even more abstract:
- How can i switch between the states?
Since the states are known before your program is executed, you can insert them into an array. Next, you have to read out the appropriate index from the array which contains your new state. Send the state and go to the next state. Propably you want to change timing, but that's easy too.
See attached screenshot for a possible solution:
hope this helps,
NorbertMessage Edited by Norbert B on 09-11-2007 07:57 AM
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.
Attachments:
StateSwitching.PNG ‏8 KB

Servlet for writing Video bytes to response

Hi there,
Thanks to all who read this.
I have developed an J2EE application that allows people to watch video and can see the application using mobile devices such as the iPhone.
Videos for the iPhone are currently encoded in MP4 format and have been tested to work. When someone hits a video URL we have a Video servlet thats writes the bytes to the response. The code is given below:
private void doGetAndPost(HttpServletRequest req, HttpServletResponse resp)
     // Get the URL up to the ? in the location
     logger.debug("doGetAndPost(HttpServletRequest, HttpServletResponse) - BEGIN");
     String requestURI = req.getRequestURI();
     String [] parts = requestURI.split("/");
     // Our filename is always the last item in our URI
     String filename = parts[parts.length-1];
     String trueFilePath = Manager.getProperty(Manager.CLIP_DIRECTORY_KEY ) +"/"+ filename;
     logger.debug("doGetAndPost(HttpServletRequest, HttpServletResponse) - Getting file: " +trueFilePath );
     String userAgent = req.getHeader("User-Agent").toLowerCase();
     String mimeType = "application/x-download";
     // if the user is browsing from a Blackberry we need to forward them to
     // the mobile view of things
     // All mobile views are a concatenation of the current views plus mobile such 'done' becomes 'doneMobile'
     if( userAgent.indexOf("blackberry") != - 1 || userAgent.indexOf("iphone") != - 1)
          mimeType="video/mp4";+
     else
            resp.setHeader("Content-Disposition", "attachment; filename="+ filename );
     try
          // Set the response for our download
          File file = new File(trueFilePath);
          int fileSize = (int)file.length();
          FileInputStream fis = new FileInputStream( file );
          resp.setContentType(mimeType);
          // Set the file size of the download....
          resp.addIntHeader("Content-Length", fileSize );
          resp.flushBuffer();
          OutputStream os = resp.getOutputStream();
          //write to out output stream
          while(true)
                    int bytedata = fis.read();
                    if (bytedata == -1)
                         break;
                    os.write(bytedata);
          // flush and close streams.....
          fis.close();
          os.flush();
          os.close();
     catch (FileNotFoundException e)
          logger.debug("doGetAndPost(HttpServletRequest, HttpServletResponse) - Unable to find file: " + trueFilePath, e );
     catch (IOException e)
          logger.debug("doGetAndPost(HttpServletRequest, HttpServletResponse) - Unable to get response output stream", e );
     logger.debug("doGetAndPost(HttpServletRequest, HttpServletResponse) - END");
}This implementation is working fine for desktop browsers but when running it on a mobile device I hit a BrokenPipe SocketException.
What I have noticed is that with mobile devices the servlet gets hit twice - seemingly once as the users selects the link and then the browser decides that it doesn't know what to do with that MIME type then it initialises its own internal media player then the servlet gets hit again to try and play the video.
The broken pipe error seems to occur after the browser has decided it doesn't now how to handle the MIME type and thus any subsequent writes to the response/connection file.
Has anyone experienced anything similar? Can anyone point out where I am going wrong?
Many thanks in advance,
Jimbobegg

Besides the error message you log does it actually work in the mobile device or not?
If it's working, then it works. The broken pipe simply means that the client is killing the socket unexpectedly. So...
As an aside wrap a buffered stream around your file in. Reading a file byte by byte is needless and painful and slow.

Writting to Bytes

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