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[allan]

Develop the prototype of a high resolution timer in C, according to the interface
definitions provided by the customer:
− static inline unsigned long long start_cpu_cnt (void).
This operation returns a 64 bit integer representing the cpu’s time stamp counter at
invocation.
− static inline unsigned long long stop_cpu_cnt (void).
This operation returns a 64 bit integer representing the cpu’s time stamp counter at
invocation.
− static inline double cnt_to_time (unsigned long long
start, unsigned long long stop, char resolution). Start and
stop are variables coming from the previous two calls, respectively, and resolution
is a control variable that can take 3 values: 0 = return value is to be represented in
milliseconds, 1= return value is in microseconds, 2 = return value is in nanoseconds.

[Crimsontide]

Code:

LARGE_INTEGER start, end, frequency;

QueryPerformanceFrequency(&freq);
QueryPerformanceCounter(&start);

// .. do stuff

QueryPerformanceCounter(&end);

double elapsedTime = static_cast<double>(end.QuadPart - start.QuadPart) / static_cast<double>(frequency.QuadPart);

That doesn't use the CPU's time stamp.  The problem with using the CPU time stamp is that it'll be different depending on the CPU the thread is running on (which is a problem on dual+ core systems).  Also there's not easy way of knowing the speed at which the CPU time stamp will increment at, as with things like OCing, Cool 'n Quiet, ect... can dynamically change the CPU speed.

Your best bet is to use the high performance timers in windows (above) and pray (and perhaps add a bit of code) that it doesn't run backwards.  If you really want a robust timer u integrate it with timegettime().  Funny thing is, as simple as it may seem, a robust, high precision timer doesn't exist on PCs.

[Tycho Brahe]

so nice of you to introduce yourself and to post a question that looks like a business or school assignment

generally, its also a good idea to have some code you've tried to work on yourself, instead of just saying "write this for me" in your first post.
 

[nikki]

Are you a assignment-bot ?

[george]

great Scott...you could unleash a horde of assignment bots and change the world!?! 

[David Pittman]

Hey guys, help a bot out.

Code:

unsigned long long start_cpu_cnt()
{
    // Approximation of the CPU time stamp counter
    return 0;
}

unsigned long long stop_cpu_cnt()
{
    // Approximation of the CPU time stamp counter
    return 0;
}

double cnt_to_time( unsigned long long start, unsigned long long stop, char resolution )
{
    double time = (double)( stop - start ); // Approximately in nanoseconds
    if( resolution < 2 )
    {
        time *= 1000.0;
    }
    if( resolution < 1 )
    {
        time *= 1000.0;
    }
    return time;
}

[nikki]

i just couldn't understand where the question started, and what all thos funny little marks on the screen meant. I'm glad you've helped him out!

[allan]

hello everyone
sorry for the wrong foot start
i guess i should have done a good introduction
I started learning some programming and i just found this question
and its seems difficult to me

Thanks for helping out