qelapsedtimer_win.cpp File Reference

#include "qelapsedtimer.h"
#include <windows.h>
#include <private/qsystemlibrary_p.h>

Go to the source code of this file.

Typedefs
typedef ULONGLONG(WINAPI *	PtrGetTickCount64) (void)

Functions
static quint64	getTickCount ()
bool	operator< (const QElapsedTimer &v1, const QElapsedTimer &v2)
static void	resolveLibs ()
static qint64	ticksToNanoseconds (qint64 ticks)

Variables
static quint64	counterFrequency = 0
static PtrGetTickCount64	ptrGetTickCount64 = 0

Typedef Documentation

PtrGetTickCount64

typedef ULONGLONG(WINAPI * PtrGetTickCount64) (void)

Definition at line 47 of file qelapsedtimer_win.cpp.

Function Documentation

getTickCount()

static quint64 getTickCount ( )

static

Definition at line 93 of file qelapsedtimer_win.cpp.

{
    resolveLibs();

    // This avoids a division by zero and disables the high performance counter if it's not available
    if (counterFrequency > 0) {
        LARGE_INTEGER counter;

        if (QueryPerformanceCounter(&counter)) {
            return counter.QuadPart;
        } else {
            qWarning("QueryPerformanceCounter failed, although QueryPerformanceFrequency succeeded.");
            return 0;
        }
    }

    if (ptrGetTickCount64)
        return ptrGetTickCount64();

    static quint32 highdword = 0;
    static quint32 lastval = 0;
    quint32 val = GetTickCount();
    if (val < lastval)
        ++highdword;
    lastval = val;
    return val | (quint64(highdword) << 32);
}

operator<()

bool operator<	(	const QElapsedTimer &	v1,
		const QElapsedTimer &	v2
	)

Definition at line 178 of file qelapsedtimer_win.cpp.

{
    return (v1.t1 - v2.t1) < 0;
}

resolveLibs()

static void resolveLibs ( )

static

Definition at line 55 of file qelapsedtimer_win.cpp.

Referenced by QFileSystemEngine::fillPermissions(), getTickCount(), isDirPath(), QFileSystemEngine::owner(), and readSymLink().

{
    static volatile bool done = false;
    if (done)
        return;

    // try to get GetTickCount64 from the system
    QSystemLibrary kernel32(QLatin1String("kernel32"));
    if (!kernel32.load())
        return;

    // does this function exist on WinCE, or will ever exist?
    ptrGetTickCount64 = (PtrGetTickCount64)kernel32.resolve("GetTickCount64");

    // Retrieve the number of high-resolution performance counter ticks per second
    LARGE_INTEGER frequency;
    if (!QueryPerformanceFrequency(&frequency)) {
        counterFrequency = 0;
    } else {
        counterFrequency = frequency.QuadPart;
    }

    done = true;
}

ticksToNanoseconds()

static qint64 ticksToNanoseconds ( qint64  ticks )

inlinestatic

Definition at line 80 of file qelapsedtimer_win.cpp.

Referenced by getTickCount().

{
    if (counterFrequency > 0) {
        // QueryPerformanceCounter uses an arbitrary frequency
        qint64 seconds = ticks / counterFrequency;
        qint64 nanoSeconds = (ticks - seconds * counterFrequency) * 1000000000 / counterFrequency;
        return seconds * 1000000000 + nanoSeconds;
    } else {
        // GetTickCount(64) return milliseconds
        return ticks * 1000000;
    }
}

Variable Documentation

counterFrequency

quint64 counterFrequency = 0

static

Definition at line 53 of file qelapsedtimer_win.cpp.

Referenced by getTickCount(), resolveLibs(), and ticksToNanoseconds().

ptrGetTickCount64

PtrGetTickCount64 ptrGetTickCount64 = 0

static

Definition at line 48 of file qelapsedtimer_win.cpp.

Referenced by getTickCount(), and resolveLibs().