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bree
Joined: 11 Jul 2011
Posts: 7
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 Posted: Tue Jul 19, 2011 6:46 pm Post subject: Copying Data from PacketStream into External Buffer |
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I want to make a function call in Snap which access data from PacketStream and copy it into my external buffer. For the first time, I already made my own code into HandleDataAvailable, which has data I want to pass into my buffer.
But, now I face a problem. I can't make a function call from SnapLib.cpp. This is the code.
| Code: | err = wombat.StartConsole(myBuf); // Entry
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myBuf is array of integer as my external buffer. After that, it goes to this code:
| Code: | consoleSnapApplicationIo->Open(myBuf);
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Then:
| Code: | void SnapApplicationIo::Open(int myBuf[])
{
...
#if 1
Stream.OnDataAvailable.SetEvent(this, &SnapApplicationIo::HandleDataAvailable);
...
}
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Then the callback function goes here.
| Code: | void SnapApplicationIo::HandleDataAvailable(PacketStreamDataEvent & Event)
{
...
Buffer Packet;
IntegerDG Packet_DG(Packet);
int buffer_size = (Packet_DG.SizeInBytes());
memcpy(&myBuf[0], &Packet_DG[0], buffer_size);
// Only for testing
ofstream output;
output.open("output.txt");
for (int i = 0; i < 32768; i++)
{
output << Packet_DG.at(i) << "\t" << myBuf[i] << endl;
}
output.close();
}
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So, my problem lies here. I want to access data (Packet) in HandleDataAvailable function. But, it's a callback function. Am I able to access the packet?
Then, I thought about overwriting the input parameter of SetEvent function in BaseEvents_Mb.h so it can receive my external buffer. But, seems I can't do that, too.
Is my approach appropriate? Is there any way I can receive PacketData from HandleDataAvailable in void SnapApplicationIo::Open(int myBuf[]) above? Or, am I missing something here?
Sorry for my bad english. And thank you.. |
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bree
Joined: 11 Jul 2011
Posts: 7
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| Posted: Wed Jul 20, 2011 12:24 am Post subject: |
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| Here I attach my code, just in case you need it... My WriteBuffer code is in SnapAppIoCon.cpp. Thank you! |
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hakan
Joined: 20 Jul 2011
Posts: 7
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| Posted: Wed Jul 20, 2011 4:14 pm Post subject: |
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I think your approach should work fine even though I think it is sort of convoluted. But one problem is that you will see only the last buffer you received since your application is single threaded and you seem to wait on a timer Sleep(20000). At the time this sleep returns, the application stops and myBuf should contain the last piece of received data.
Moreover, I would like to point out a few things that, I think, you should correct.
| Code: |
//Instead of WriteBuffer(Innovative::Buffer Packet)
WriteBuffer(Innovative::Buffer &Packet)
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since one would not want to copy the whole buffer but pass a reference to it.
Another issue is the way you are copying the data
| Code: |
//Instead of memcpy(&myBuf[0], &Packet_DG[0], buffer_size);
for (int i = 0; i < Packet_DG.SizeInInts(); i++)
myBuf[i] = Packet_DG[i];
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memcpy makes an assumption that the IntegerDG class uses an array for its data. I do not think you should make such an assumption. I think a safer way would be to copy data in your array by looping.
Let me know if you have any further questions.
Hakan |
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bree
Joined: 11 Jul 2011
Posts: 7
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| Posted: Wed Jul 20, 2011 6:14 pm Post subject: |
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Okay. So, yes.. It only saves the last pieces of received data. But, my main problem is about accessing PacketStream from void SnapApplicationIo::Open(int myBuf[]).
Seems like I can't get that Packet from anywhere else but HandleDataAvailable callback function. I think, in order to make function call from SnapLib, I need to access those PacketStream in HandleDataAvailable from another function.
So, this is my approach. I send myBuf[] from the first time until it reaches HandleDataAvailable. But, I was stuck. I can't overwrite SetEvent function. So, is there any safer way to copy PacketStream into external buffer by accessing PacketStream from SnapLib, for instance?
Anyway, Hakan. Thanks for pointing those issues. I really help me to understand the whole picture.  |
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bree
Joined: 11 Jul 2011
Posts: 7
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| Posted: Thu Jul 21, 2011 12:47 am Post subject: |
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Sorry. I can't find Edit button in this page. I'd edited my last question.
Okay. So, yes.. It only saves the last pieces of received data. But, my main problem is about accessing PacketStream from void SnapApplicationIo::Open(int myBuf[]). Seems like I can't get that Packet from anywhere else but HandleDataAvailable callback function. In order to make function call from SnapLib, I need to access those PacketStream from another function.
So, this is my approach. I send myBuf[] from the first time (StartConsole()) until it reaches HandleDataAvailable. But, I was stuck. I can't overwrite SetEvent function. So, I made another try.
This time, I'd tried global variable in SnapAppIoCon.app. I copied Buffer Packet in HandleDataAvailable into Packet2 (Innovative::Buffer). Instead of sizeinbytes = 131072 (Test2.txt) as Packet in HandleDataAvailable is, I got sizeinbytes = 0 (Test.txt). So, I was stuck again.
So, is there any safer way to copy PacketStream from SnapLib.cpp into external buffer by accessing Buffer Packet? I need to get those Packet from a function call. This is what I try.
| Code: |
// In SnapApplicationIo.h
Innovative::Buffer Packet2;
// In SnapApplicationIo.cpp
void SnapApplicationIo::HandleDataAvailable(PacketStreamDataEvent & Event)
{
...
Packet2 = Packet;
ofstream output;
output.open("Test2.txt");
output << Packet2.SizeInBytes() << endl;
output.close();
}
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I collected Packet3 as I hope it contains same packet as Packet (or Packet2) does.
| Code: |
void SnapApplicationIo::HandleDataAvailable(PacketStreamDataEvent & Event)
{
Buffer Packet3;
Packet3 = SnapApplicationIo::Packet2;
ofstream output;
output.open("Test.txt");
output << Packet3.SizeInBytes() << endl;
output.close();
}
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Anyway, Hakan. Thanks for pointing those issues. I really help me to understand the whole picture.
I attach SnapApplicationIo.cpp and the header file just in case you need it. The rest has been attached before.
Thank you! |
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hakan
Joined: 20 Jul 2011
Posts: 7
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| Posted: Thu Jul 21, 2011 12:00 pm Post subject: |
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If I understand you correctly, what you are trying to achieve is to export the received data outside of the ApplicationIo class.
All the methods you tried can be made to work but let's pick a cleaner method as opposed to defining global variables or changing function interfaces to pass around data.
Please look at the code I included. I added a new class into the ApplicationIo header which is a data exchange interface class. And changed the ApplicationIo constructor as to take this interface as a parameter. When the data is received data is pushed to this interface in the HandleDataAvailable.
Here is the code I added
| Code: |
// In the Application Io header
//======================================
// CLASS IDataExportInterface -- Interface for exporting data
//======================================
class IDataExportInterface
{
public:
~IDataExportInterface() { }
virtual void Export(Innovative::Buffer &a_buffer) = 0;
};
// In your application please add your CollectData class
//===========================================================================
// CLASS CollectData -- Store collected buffers
//===========================================================================
class CollectData : public IDataExportInterface
{
private:
std::vector<Innovative::Buffer> &Storage;
public:
CollectData(std::vector<Innovative::Buffer> &storage):
Storage(storage) {}
void Export(Innovative::Buffer &a_buffer)
{
Storage.push_back(a_buffer);
}
};
// Also pass a pointer to your IDataExportInterface class
std::vector<Innovative::Buffer> Buffers;
CollectData myExport(Buffers);
UI = new UserInterface(this);
Io = new ApplicationIo(UI, &myExport );
GL = new GuiLoader;
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I am adding ApplicationIo files also Form1 file. In Form1 only thing that is relevant is Form1::Form1 and CollectData class. Please compare the attached files to the standard files and see the changes I made to the standard example.
Hakan |
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bpssoft
Joined: 07 Jun 2011
Posts: 29
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| Posted: Wed Nov 16, 2011 4:55 am Post subject: |
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I want to copy the Buffer to another thread, but the following code makes it to slow. When i copy the buffer to the other thread it wont dispose in memory. I can't call Delete Buffer. How can i fast copy / move the data to another thread and dispose it?
| Code: | int PacketSize = Packet_DG.SizeInInts();
int* Arrays = new int[PacketSize]();
for (int i = 0; i < PacketSize; i++)
{
Arrays[i] = Packet_DG[i];
}
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jhenderson
Site Admin
Joined: 07 Mar 2006
Posts: 2254
Location: So. Cal. USA
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| Posted: Mon Nov 21, 2011 11:40 am Post subject: |
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I would recommend performing the allocation of Arrays early in the application, so that this time-consuming function need not be performed during data streaming. Likewise, it's deallocation can occur late in the application, not during streaming.
Secondly, if you include the call below in the constructor of ApplicationIo:
// Use IPP performance memory functions.
Init::UsePerformanceMemoryFunctions();
then you can use the fast IPP functions to perform copy operations.
#include <IppMemoryUtils_Mb.h>
void IppCopyInt32Buffer( const int *src_buffer, int *dst_buffer, size_t size );
void IppCopyInt64Buffer( const ii64 *src_buffer, ii64 *dst_buffer, size_t size );
void IppCopyByteBuffer( const unsigned char *src_buffer, unsigned char *dst_buffer, size_t size ); |
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