I was interested in learning how JNA relates a memory Address (an integer) with the contains of the addressed memory. In C++ a pointer is just a variable that stores a memory address that you can assign to and also dereference, so if a function returns a memory address (pointer) you can dereference it to view its contents. I don't know how this would be possible in JNA (I read the doc. but it seems you can only see the contents of a pointer but no the address). Anyway this is the code I would like to map to JNA:

#include <windows.h> #include <stdio.h> #include <math.h> #include "VirtualDevice.h"

#define DOF1 8 #define DOF 6

//CreateFileMappingW, CloseHandle, MapViewofFile, RtlMoveMemory and FlushViewOfFile are defined in Kernel32.dll but C imports them implicitly typedef struct tag_VIRTUAL_DEVICE { //VIRTUAL DEVICE - STATE float fPositionIn[DOF1]; float fVelIn[DOF]; short fCamera[320*240]; int fIdentifier; }

static VIRTUAL_DEVICE *pVirtualDevice;

static HANDLE hShare;

BOOL OpenShareMemory(char *cpName) { if( pVirtualDevice != NULL){ MessageBox(NULL,"Error: THE SHARE MEMORY WAS ALREADY OPEN", "Error",MB_OK); return FALSE; }

hShare = CreateFileMappingW((HANDLE)0xFFFFFFFF,NULL, PAGE_READWRITE, 0, sizeof(VIRTUAL_DEVICE), cpName);

if(hShare == NULL){ MessageBox(NULL,"Error:Open Virtual Device::CreateFileMapping","Error",MB_OK); return FALSE; }else{ pVirtualDevice = (VIRTUAL_DEVICE *) MapViewOfFile(hShare,FILE_MAP_ALL_ACCESS, 0, 0, sizeof(VIRTUAL_DEVICE)); } if(pVirtualDevice == NULL){ MessageBox(NULL,"Error: Open Virtual Device::MapViewOfFile","Error",MB_OK); return FALSE; } return TRUE; }

BOOL CloseShareMemory() { if(pVirtualDevice != NULL) { if( FlushViewOfFile(pVirtualDevice, sizeof(VIRTUAL_DEVICE)) == 0){ MessageBox(NULL,"Error:Close Virtual Device::FlushViewOfFile","Error",MB_OK); return FALSE; } if( UnmapViewOfFile(pVirtualDevice) == 0){ MessageBox(NULL,"Error: Close Virtual Device::UnmapViewOfFile","Error",MB_OK); return FALSE; } if( CloseHandle(hShare) == 0){ MessageBox(NULL,"Error: Close Virtual Device::CloseHandle","Error",MB_OK); return FALSE; } pVirtualDevice = NULL; return TRUE; }else{ MessageBox(NULL,"Error: THE SHARE MEMORY WAS ALREADY CLOSE","Error",MB_OK); return FALSE; } }

BOOL ReadShareMemory(VIRTUAL_DEVICE *pfData) {

if(pVirtualDevice == NULL){ MessageBox(NULL,"Error:Read Virtual Device CANT FIND THE SHARE MEMORY","Error",MB_OK); return FALSE; } // RtlMoveMemory((VIRTUAL_DEVICE *)pfData, (VIRTUAL_DEVICE *)pVirtualDevice, sizeof(VIRTUAL_DEVICE));

return TRUE; }

BOOL WriteShareMemory(VIRTUAL_DEVICE *pfData) {

int i=0;

if(pVirtualDevice == NULL){ MessageBox(NULL,"Error:Read Virtual Device CANT FIND THE SHARE MEMORY","Error",MB_OK); return FALSE; }

for(i=0;i<DOF1;i++) { pVirtualDevice->fPositionIn[i] = pfData->fPositionIn[i]; }

for(i=0;i<DOF;i++) { pVirtualDevice->fVelIn[i] = pfData->fVelIn[i]; }

for(i=0;i<DOF2*0.5;i++) { pVirtualDevice->compensacion[i] = pfData->compensacion[i]; }

for(i=0;i<320*240;i++) { pVirtualDevice->fCamera[i] = pfData->fCamera[i]; }

pVirtualDevice->fIdentifier[i] = pfData->fIdentifier[i];

if( FlushViewOfFile(pVirtualDevice, sizeof(VIRTUAL_DEVICE)) == 0){ MessageBox(NULL,"Error: Close Virtual Device::FlushViewOfFile","Error",MB_OK); return FALSE; } return TRUE; }

//END

If I map HANDLE to int, should I map: pVirtualDevice = (VIRTUAL_DEVICE *) MapViewOfFile(hShare,FILE_MAP_ALL_ACCESS, 0, 0, sizeof(VIRTUAL_DEVICE)); to this: - Pointer pVirtualDevice = MapViewOfFile(hShare, FILE_MAP_ALL_ACCESS, 0, 0, SIZE_V_DEVICE); //I define manually FILE_MAP_ALL_ACCESS and SIZE_V_DEVICE

I another file I define the Kernel32 Interface public interface Kernel32 extends StdCallLibrary { // Method declarations, constant and structure definitions go here Kernel32 INSTANCE = (Kernel32) Native.loadLibrary("C:\\windows\\system32\\kernel32.dll", Kernel32.class);

Kernel32 SYNC_INSTANCE = (Kernel32) Native.synchronizedLibrary(INSTANCE);

public static final int PAGE_READONLY = 0x02; public static final int PAGE_READWRITE = 0x04; public static final int PAGE_WRITECOPY = 0x08;

public static final int FILE_MAP_COPY = 0x0001; public static final int FILE_MAP_WRITE = 0x0002; public static final int FILE_MAP_READ = 0x0004; public static final int FILE_MAP_ALL_ACCESS = 0xF001F; public static final int INVALID_HANDLE_VALUE = -1;

Pointer CreateFileMappingW(int hFile, int lpFileMappingAttributes, int flProtect, int dwMaximumSizeLow, int dwMaximumSizeHigh, String lpName); ....

I tried this way but I did not work. Any suggestions?? thanks.

2008/9/9 Timothy Wall <twal...@dev.java.net>