Thread: virtual memory program

Code:

// VMStatsDlg.cpp : implementation file
//

#include "stdafx.h"
#include "VMStats.h"
#include "VMStatsDlg.h"

#include <winbase.h>	// For GlobalMemoryStatus and MEMORYSTATUS

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif


void AFXAPI DDX_Text_Custom(CDataExchange* pDX, int nIDC, unsigned long& value);
void AFX_CDECL My_DDX_TextWithFormat(CDataExchange* pDX, int nIDC,
	LPCTSTR lpszFormat, UINT nIDPrompt, ...);

/////////////////////////////////////////////////////////////////////////////
// CAboutDlg dialog used for App About

class CAboutDlg : public CDialog
{
public:
	CAboutDlg();

// Dialog Data
	//{{AFX_DATA(CAboutDlg)
	enum { IDD = IDD_ABOUTBOX };
	//}}AFX_DATA

	// ClassWizard generated virtual function overrides
	//{{AFX_VIRTUAL(CAboutDlg)
	protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
	//}}AFX_VIRTUAL

// Implementation
protected:
	//{{AFX_MSG(CAboutDlg)
	//}}AFX_MSG
	DECLARE_MESSAGE_MAP()
};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
	//{{AFX_DATA_INIT(CAboutDlg)
	//}}AFX_DATA_INIT
}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	//{{AFX_DATA_MAP(CAboutDlg)
	//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
	//{{AFX_MSG_MAP(CAboutDlg)
		// No message handlers
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CVMStatsDlg dialog

CVMStatsDlg::CVMStatsDlg(CWnd* pParent /*=NULL*/)
	: CDialog(CVMStatsDlg::IDD, pParent)
{
	//{{AFX_DATA_INIT(CVMStatsDlg)
	m_AvPage = 0;
	m_AvPhys = 0;
	m_AvVirt = 0;
	m_Percent = 0;
	m_TotPage = 0;
	m_TotPhys = 0;
	m_TotVirt = 0;
	//}}AFX_DATA_INIT
	// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
	m_hIcon = AfxGetApp()->LoadIcon(IDI_CHIPICON);

    m_nReserved = m_nCommitted = m_nUsed = 0;
}

void CVMStatsDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
/*
	//{{AFX_DATA_MAP(CVMStatsDlg)
	DDX_Text(pDX, IDC_AVPAGE, m_AvPage);
	DDX_Text(pDX, IDC_AVPHYS, m_AvPhys);
	DDX_Text(pDX, IDC_AVVIRT, m_AvVirt);
	DDX_Text(pDX, IDC_PERCENT, m_Percent);
	DDX_Text(pDX, IDC_TOTPAGE, m_TotPage);
	DDX_Text(pDX, IDC_TOTPHYS, m_TotPhys);
	DDX_Text(pDX, IDC_TOTVIRT, m_TotVirt);
	//}}AFX_DATA_MAP
*/
	DDX_Text_Custom(pDX, IDC_AVPAGE, m_AvPage);
	DDX_Text_Custom(pDX, IDC_AVPHYS, m_AvPhys);
	DDX_Text_Custom(pDX, IDC_AVVIRT, m_AvVirt);
	DDX_Text_Custom(pDX, IDC_PERCENT, m_Percent);
	DDX_Text_Custom(pDX, IDC_TOTPAGE, m_TotPage);
	DDX_Text_Custom(pDX, IDC_TOTPHYS, m_TotPhys);
	DDX_Text_Custom(pDX, IDC_TOTVIRT, m_TotVirt);
}

BEGIN_MESSAGE_MAP(CVMStatsDlg, CDialog)
	//{{AFX_MSG_MAP(CVMStatsDlg)
	ON_WM_SYSCOMMAND()
	ON_WM_PAINT()
	ON_WM_QUERYDRAGICON()
	ON_WM_CREATE()
	ON_WM_DESTROY()
	ON_WM_TIMER()
	ON_BN_CLICKED(IDC_ABOUT, OnAbout)
	ON_BN_CLICKED(IDC_RESERVE, OnReserve)
	ON_BN_CLICKED(IDC_USE, OnUse)
	ON_BN_CLICKED(IDC_RADIODEC, OnRadiodec)
	ON_BN_CLICKED(IDC_RADIOHEX, OnRadiohex)
	ON_BN_CLICKED(IDC_COMMIT, OnCommit)
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CVMStatsDlg message handlers

BOOL CVMStatsDlg::OnInitDialog()
{
	CDialog::OnInitDialog();

	// Add "About..." menu item to system menu.

	// IDM_ABOUTBOX must be in the system command range.
	ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
	ASSERT(IDM_ABOUTBOX < 0xF000);

	CMenu* pSysMenu = GetSystemMenu(FALSE);
	if (pSysMenu != NULL)
	{
		CString strAboutMenu;
		strAboutMenu.LoadString(IDS_ABOUTBOX);
		if (!strAboutMenu.IsEmpty())
		{
			pSysMenu->AppendMenu(MF_SEPARATOR);
			pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
		}
	}

	// Set the icon for this dialog.  The framework does this automatically
	//  when the application's main window is not a dialog
	SetIcon(m_hIcon, TRUE);			// Set big icon
	SetIcon(m_hIcon, FALSE);		// Set small icon
	
	// TODO: Add extra initialization here
 
    m_DisplayFmtHex = TRUE;  
   TCHAR szBuf[60];
   _stprintf(szBuf, __TEXT("System page size %dKB"), m_PageSize/1024);
   ::SetDlgItemText(m_hWnd, IDC_PAGESIZE, szBuf);
//   SetDlgItemText(IDC_PAGESIZE, szBuf);
   _stprintf(szBuf, __TEXT("Virtual memory allocation granularity %dKB"), m_Granularity/1024);
   ::SetDlgItemText(m_hWnd, IDC_GRANULARITY, szBuf);  
//  SetDlgItemText(IDC_GRANULARITY, szBuf);

   CheckRadioButton(IDC_RADIODEC, IDC_RADIOHEX, IDC_RADIOHEX);

	return TRUE;  // return TRUE  unless you set the focus to a control
}

void CVMStatsDlg::OnSysCommand(UINT nID, LPARAM lParam)
{
	if ((nID & 0xFFF0) == IDM_ABOUTBOX)
	{
		CAboutDlg dlgAbout;
		dlgAbout.DoModal();
	}
	else
	{
		CDialog::OnSysCommand(nID, lParam);
	}
}

// If you add a minimize button to your dialog, you will need the code below
//  to draw the icon.  For MFC applications using the document/view model,
//  this is automatically done for you by the framework.

void CVMStatsDlg::OnPaint() 
{
	if (IsIconic())
	{
		CPaintDC dc(this); // device context for painting

		SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

		// Center icon in client rectangle
		int cxIcon = GetSystemMetrics(SM_CXICON);
		int cyIcon = GetSystemMetrics(SM_CYICON);
		CRect rect;
		GetClientRect(&rect);
		int x = (rect.Width() - cxIcon + 1) / 2;
		int y = (rect.Height() - cyIcon + 1) / 2;

		// Draw the icon
		dc.DrawIcon(x, y, m_hIcon);
	}
	else
	{
		CDialog::OnPaint();
	}
}

// The system calls this to obtain the cursor to display while the user drags
//  the minimized window.
HCURSOR CVMStatsDlg::OnQueryDragIcon()
{
	return (HCURSOR) m_hIcon;
}

int CVMStatsDlg::OnCreate(LPCREATESTRUCT lpCreateStruct) 
{
	if (CDialog::OnCreate(lpCreateStruct) == -1)
		return -1;
	
	// TODO: Add your specialized creation code here

	SYSTEM_INFO SystemInfo;

	GetSystemInfo(&SystemInfo);
	m_PageSize = SystemInfo.dwPageSize;
	m_Granularity = SystemInfo.dwAllocationGranularity;

	m_MemoryStatus.dwLength = sizeof(m_MemoryStatus);
	GlobalMemoryStatus(&m_MemoryStatus);
	m_AvPage = m_MemoryStatus.dwAvailPageFile;
	m_AvPhys = m_MemoryStatus.dwAvailPhys;
	m_AvVirt = m_MemoryStatus.dwAvailVirtual;
	m_Percent = m_MemoryStatus.dwMemoryLoad;
	m_TotPage = m_MemoryStatus.dwTotalPageFile;
	m_TotPhys = m_MemoryStatus.dwTotalPhys;
	m_TotVirt = m_MemoryStatus.dwTotalVirtual;

	if((m_TimerID = SetTimer(1, 100, NULL)) == 0){
		MessageBox("No system timer available");
	}
	return 0;
}

void CVMStatsDlg::OnDestroy() 
{
	CDialog::OnDestroy();
	
	// TODO: Add your message handler code here
	if(m_TimerID != 0)
		KillTimer(m_TimerID);	
}

void CVMStatsDlg::OnTimer(UINT nIDEvent) 
{
	// TODO: Add your message handler code here and/or call default
	BOOL changed = FALSE;
	m_MemoryStatus.dwLength = sizeof(m_MemoryStatus);
	GlobalMemoryStatus(&m_MemoryStatus);
	if(m_AvPage != m_MemoryStatus.dwAvailPageFile){
		m_AvPage = m_MemoryStatus.dwAvailPageFile;
		changed = TRUE;
	}
	if(m_AvPhys != m_MemoryStatus.dwAvailPhys){
		m_AvPhys = m_MemoryStatus.dwAvailPhys;
		changed = TRUE;
	}
	if(m_AvVirt != m_MemoryStatus.dwAvailVirtual){
		m_AvVirt = m_MemoryStatus.dwAvailVirtual;
		changed = TRUE;
	}
	if(m_Percent != m_MemoryStatus.dwMemoryLoad){
		m_Percent = m_MemoryStatus.dwMemoryLoad;
		changed = TRUE;
	}
	if(m_TotPage != m_MemoryStatus.dwTotalPageFile){
		m_TotPage = m_MemoryStatus.dwTotalPageFile;
		changed = TRUE;
	}
	if(m_TotPhys != m_MemoryStatus.dwTotalPhys){
		m_TotPhys = m_MemoryStatus.dwTotalPhys;
		changed = TRUE;
	}
	if(m_TotVirt != m_MemoryStatus.dwTotalVirtual){
		m_TotVirt = m_MemoryStatus.dwTotalVirtual;
		changed = TRUE;
	}
	if(changed)UpdateData(FALSE);
	CDialog::OnTimer(nIDEvent);
}

void CVMStatsDlg::OnAbout() 
{
	// TODO: Add your control notification handler code here
	CAboutDlg AboutDlg;
	AboutDlg.DoModal();	
}

void CVMStatsDlg::OnReserve() 
{
	// TODO: Add your control notification handler code here
	m_DataBlocks[m_nReserved++] = (char *)VirtualAlloc(NULL, 65536, MEM_RESERVE, PAGE_READWRITE);
}

void CVMStatsDlg::OnUse() 
{
	// TODO: Add your control notification handler code here
    if(m_nCommitted > m_nUsed){
        char *p = m_DataBlocks[m_nUsed++];
        for(int i = 0; i < 65536; i++){
            for(int j = 0; j < 256; j++)
                *p = j;
            p++;
        }
    }
}

void CVMStatsDlg::OnRadiodec() 
{
	// TODO: Add your control notification handler code here
	m_DisplayFmtHex = FALSE;
	
}

void CVMStatsDlg::OnRadiohex() 
{
	// TODO: Add your control notification handler code here
	m_DisplayFmtHex = TRUE;
}


void AFXAPI DDX_Text_Custom(CDataExchange* pDX, int nIDC, unsigned long& value)
{
	if (pDX->m_bSaveAndValidate)
		My_DDX_TextWithFormat(pDX, nIDC, _T("%X"), AFX_IDP_PARSE_INT, &value);
	else
        if(((CVMStatsDlg *)AfxGetMainWnd())->m_DisplayFmtHex)
		    My_DDX_TextWithFormat(pDX, nIDC, _T("%X"), AFX_IDP_PARSE_INT, value);
        else
		    My_DDX_TextWithFormat(pDX, nIDC, _T("%d"), AFX_IDP_PARSE_INT, value);
}


void AFX_CDECL My_DDX_TextWithFormat(CDataExchange* pDX, int nIDC,
	LPCTSTR lpszFormat, UINT nIDPrompt, ...)
	// only supports windows output formats - no floating point
{
	va_list pData;
	va_start(pData, nIDPrompt);

	HWND hWndCtrl = pDX->PrepareEditCtrl(nIDC);
	TCHAR szT[32];
	if (pDX->m_bSaveAndValidate)
	{
		/*
		// the following works for %d, %u, %ld, %lu
		::GetWindowText(hWndCtrl, szT, _countof(szT));
		if (!_AfxSimpleScanf(szT, lpszFormat, pData))
		{
			AfxMessageBox(nIDPrompt);
			pDX->Fail();        // throws exception
		}
		*/
	}
	else
	{
		wvsprintf(szT, lpszFormat, pData);
			// does not support floating point numbers - see dlgfloat.cpp
		SetWindowText(hWndCtrl, szT);
	}

	va_end(pData);
}

void CVMStatsDlg::OnCommit() 
{
	// TODO: Add your control notification handler code here
    if(m_nReserved > m_nCommitted)
	    VirtualAlloc(m_DataBlocks[m_nCommitted++], 65536, MEM_COMMIT, PAGE_READWRITE);	
}

hi,

can anyone help? I can't work out a few things relating to the above code:

- What do the reserve,commit and use buttons do?

- What is the difference between the page file and
virtual memory?

- How does this approach differ to simply using malloc
and when would it be more appropriate?

- What Win32 function is used in the
timer handler to obtain system virtual memory
information?



thanks, any input would be great.