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Oh - still getting those reversed times
static Spec_Thread double ddwt_was;
if(ddwt_was!=0)
if(ddwt<ddwt_was)
ddwt=ddwt;
ddwt_was=ddwt;
ddwt 22589372.894629
ddwt_was 22589372.895075
And this is fixed using:
{
DWORD threadAffMask=SetThreadAffinityMask(GetCurrentThread(),1);
QueryPerformanceCounter(&HPT_PerformanceCount);
SetThreadAffinityMask(GetCurrentThread(),threadAffMask );
}
So - seems - that code actually does work, you don't need to do it for the entire thread, just with every call as in the example code.
Sorry for the confusion.
So - seems - here anyway - that you can get time reversals if you let the time be measured on any core.
You avoid them if you access the interrupt timer via KUSER_SHARED_DATA though that doesn't have the same resolution on my computer as the QueryPerformanceCounter (only changes every 1ms - though it seems likely that it reports the exact time at the moment that it changes - so you could time an exact ms by just waiting in a busy loop for it to change).
But to get the clocks running at a constant rate you need to force the OS to use HPET. Doesn't seem to be anyway for a program to access HPET if Windows isn't using it as far as I can see anyway.
HPET is guaranteed, on Intel machines anyway, to be accurate to 0.05 % over 1 ms and
http://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/software-developers-hpet-spec-1-0a.pdf[^]
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I don't know if you're aware that HPET implementation on some motherboards are flaky, in particular AMD Chipsets, may also have problems with boards that have SMI incorrectly generating too many interrupts.
Take a look at the foot of the Wiki page for High Performance Event Timer
Linus Torvald's rant:
HPET grumbles
windows/hardware/gg463347.aspx
Lastly, some source code you might wish to take a look at ($0.00)
zip
I did wonder if you might want to look at the source code for VirtualBox with has options to enable HPET features for VMs.
--* OFF TOPIC & Previously touched upon *--
There have been problems with multi-core timer issues, and apparently there is serialized cpu instruction to avoid out-of-order execution affecting timer readings. RDTSC (not serialized) RDTSCP (new)
"It's true that hard work never killed anyone. But I figure, why take the chance." - Ronald Reagan
That's what machines are for.
Got a problem?
Sleep on it.
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Oh right, maybe that is why some users have issues enabling HPET while others find it works just fine for them.
When it comes to musicians, if this is indeed the best way to achieve sub-millisecond precision on Windows with true exact timing - well they might well when buying new computers choose to buy one that can have the HPET enabled without causing problems. You often get exchange of notes and musicians asking each other which computer makes in their experience work best for music making. Normally ones that score well for silence, and latency and DPC. But this seems another thing to add to the list.
It is hard to over-stress how important it is for musicians to be able to play midi notes and record them with sub millisecond precision, and at least - not with multi-millisecond errors.
I just checked it up, I think from this post that RDTSCP is just like RDTSC except that it also tells you the processor id.
Example assembly code here The Terran Comedy[^]
But so long as you don't mind forcing your thread to go to core 1 whenever it checks the time, then SetThreadAffinityMask seems the way to go - I was wrong earlier when I said it seemed that the thread has to sleep first before it works, that was that bug in my own code.
It seems to work instantly somehow - does this mean the scheduler instantly moves the thread to the other core?
I suspect that probably it looks ahead in the code and when it sees a SetThreadAffinityMask in the near future moves it to another core in anticipation.
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Hi
Please Please somebody post comprehensive series in win32 API programming with visual c++ 2012.
I need it urgently since without the knowledge of it iam having problem in my programming career.
Please make it simple and cover all topics from easy to intermediate to advanced.
regards
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naseer861 wrote: post comprehensive series in win32 API
In a forum posting? Are you serious? Do you even realize how huge the Win32 API is?
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Dude i am not talking about the huge API
atleast start from the basic.
Somethings are understood as obviuos.
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(something is probably lost in translation)
You are asking for a C++ Win32 guide that covers ALL topics from easy to intermediate to advanced ?
What did your own research on the subject returned ? did you go to a library ? what did google/bing returned ?
Nihil obstat
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Need a free image library that can handle png xresolution and yresolution.
I need it to be compatible with visual studio 6.0
I greatful for your help.
Sincerely
Andla
Need a free image library that can handle png xresolution and yresolution.
I need it to be compatible with visual studio 6.0
I greatful for your help.
Sincerely
Andla
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This[^] one is pretty good ... hope it helps ...
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Hi,
I have narrowed down my CfileDIalog problem as to have something to do with MSCOWRKS.DLL
Does anyone know the pourpose of this DLL can it be removed and is there a way of removing it from my
MFC C++ app
Thanks
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As far as I can ascertain (as suggested previously) this is part of the .NET framework so should not be included in an MFC project. If you are trying to mix MFC with Winforms (C++/CLI) you will have problems.
Use the best guess
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I will try to re-do my project
Thanks
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I already told you before that this DLL was part of .Net and shouldn't even be in an MFC/C++ application (unless you put it there on purpose). You probably made a .Net project inadvertently.
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Hi all,
on dialog box i have a static contol i want to fit its width according to its text when dialog box is open or text change .
i use this but the control width is set less than text width..
CString strText;
m_label.GetWindowText(strText);
CClientDC dc(this);
CFont* pFont = GetFont();
CFont* pOldFont = (CFont*)dc.SelectObject(pFont);
CSize sizeText = dc.GetTextExtent(strText);
dc.SelectObject(pOldFont);
CRect rcText;
m_label.GetWindowRect(rcText);
CRect dlg_stc=rcText;
this->ScreenToClient(dlg_stc);
rcText = dlg_stc;
rcText.right = min(rcText.right, sizeText.cx);
CRect new_rect=rcText;
m_label.MoveWindow(new_rect);
can anybody help me to do this.
thanks.
modified 13-Mar-13 3:14am.
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I have had a similar issue in the past and used the GetTextExtentPoint32() function. I also found it necessary to add the size of a couple of extra characters as the calculation seems very precise.
Use the best guess
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Richard MacCutchan wrote: I have had a similar issue in the past and used the
GetTextExtentPoint32() function. I also found it necessary to add
the size of a couple of extra characters as the calculation seems very precise.
this also gives the same width.
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Le@rner wrote: rcText.right = min(rcText.right, sizeText.cx);
try this for the above statement,
rcText.right = rcText.left + sizeText.cx
and try to avoid using unwanted temporary variables, you can simply have as below,
CRect rcLabel;
m_label.GetWindowRect(rcLabel); rcLabel.right = rcLabel.left + sizeText.cx; ScreenToClient(rcLabel); m_label.MoveWindow(rcLabel);
Do your Duty and Don't Worry about the Result
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I have downloaded IVT library ( Integrating Vision Toolkit), I made my app dependent on this library ( as DSP project in VC6.0) , I can partially compile the app because I get "permission denied" when I get to #include preprocessor statement.
I have checked the directory permissions and I have grayed out "read only" checked in IVT directory.
All of the sources I used so far said that such grayed out "read only" checked ( in XP) does not make any difference (?) when directories are involved.
All of my app directories have that grayed out "read only" checked and I have no problem including other (OpenCV) libraries.
I am tempted to recopy / re-download the IVT files , but would like to hear from the forum what is going on here.
Appreciate any advise.
Cheers
Vaclav
Addendum
Here is the real code snippet
I must be doing something really stupid.
#pragma message("include IVT ")
#include <Z:\Program Files\IVT\ivt-1.3.19\IVT\src> // fails
#include <Z:\Program Files\IVT\ivt-1.3.19\IVT\src\Calibration> // fails
#include <Z:\Program Files\IVT\ivt-1.3.19\IVT\src\Calibration\Calibration.h> // OK
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You cannot include complete directories in C/C++.
Use the best guess
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You can't include a folder, only a file. If you want to add the folders to the list of places to look for include files, add them to project settings (think it's called "Additional include folders") or in the VC6 Tools-Options.
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Hello all!
I'm working on a program in which, I'm receiving the bytes of an image and after storing this creating a bitmap to display.
This is my Main code Please see this..
static char buff[MAX_SIZE];
int num;
//receiving the bytes from a client
num=recv(Socket, buff, sizeof(buff), 0);
// progress the buffer
//ifstream creation
std::ifstream is;
is.open(buff, std::ios::binary);
is.seekg(0, std::ios::end);
num = is.tellg();
is.seekg(0, std::ios::beg);
//reading buffer
is.read(buff, num);
tagBITMAPFILEHEADER bfh = *(tagBITMAPFILEHEADER*)buff;
tagBITMAPINFOHEADER bih = *(tagBITMAPINFOHEADER*)(buff+sizeof(tagBITMAPFILEHEADER));
RGBQUAD rgb = *(RGBQUAD*)(buff+sizeof(tagBITMAPFILEHEADER)+sizeof(tagBITMAPINFOHEADER));
BITMAPINFO bi;
bi.bmiColors[0] = rgb;
bi.bmiHeader = bih;
char* pPixels = (buff+bfh.bfOffBits);
char* ppvBits;
hbitmap = CreateDIBSection(NULL, &bi, DIB_RGB_COLORS, (void**) &ppvBits, NULL, 0);
SetDIBits(NULL, hbitmap, 0, bih.biHeight, pPixels, &bi, DIB_RGB_COLORS);
GetObject(hbitmap, sizeof(BITMAP), &cBitmap);
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