Create A Circular Buffer On The Heap?

Feb 24, 2010

How can I create a circular buffer on the heap in VB.NET ? This would be used for audio playback via P/Invoke to winmm.dll waveoutopen and waveoutwrite to support development of a software synth. I currently use the marshall class to build a regular array of bytes in the heap.


.net - High Speed Circular Buffer?

Jun 8, 2012

I have been asked to improve the memory efficiency of an application that is used for high speed data acquisition. After running the VS memory profiler several times and scanning the projects for obvious issues I came to the following conclusion: despite using a fixed size circular buffer for storing acquired sample points, the RAM usage increases relative to the polling period. For example: polling data for one signal at 2 microseconds can use 5 times more memory (private bytes) than when running at 50 microseconds ... even though the buffer size is the same.

The circular buffer is an array of SamplePoint objects. Each of these objects contains an array of Shorts (16 bit) for corresponding data per signal and one date object (8 bytes) for the time stamp. For efficiency, the circular buffer is Redimmed only once every time it begins polling and filled with empty sample points which are then "assigned".

Also, it seems that when we stop and run the application it hogs even more memory each time as though the Redim is not releasing the previous array. My questions boil down to the following: What is most memory efficient way of implementing a circular buffer containing managed objects which have arrays?Also, how and why is memory usage increasing with a fixed size array with different polling speeds? Does the garbage collector not have time? Do local variables get disposed of IMMEDIATELY when a sub or function exits?These are some of the doubts and concerns that I would like to rule out before proceeding.


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VS 2010 DirectSound - Streaming / Circular Buffer?

Feb 8, 2012

I use the following code (with Imports Microsoft.DirectX.DirectSound and Microsoft.DirectX) to play sound using an 8 second static buffer:

Dim SD As Device = New Device
SD.SetCooperativeLevel(Me.Handle, CooperativeLevel.Priority)
Dim MS As New IO.MemoryStream(Gbuffer) ' Gbuffer is byte array with properly formatted WAV data
Dim waveFormat As New WaveFormat
waveFormat.SamplesPerSecond = 44100
[Code] .....

What I would like to do next is to change to a "circular" or "streaming" buffer so that I can write new data "on the fly". I've done a lot of Googling but can't quite see how to adapt my present code to use a circular buffer. I can get the current write and play positions using Msb.GetCurrentPosition(iPlayPos, iWritePos) but how do I actually insert new data into the buffer? I have tried "manually" writing new data into my Gbuffer byte array but that doesn't work - I guess once a sound has been played through once, the data is cached somewhere and the contents of Gbuffer are not used again.

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Buffer Cannot Be Null - Parameter Name: Buffer

Dec 15, 2011


This is my code for retrieving pictures, it was working before but then i accidentally deleted the table and i created it again with the same name and same fields. and now whenever i open the form with the picture, there was a message box error. it says Buffer cannot be null. Parameter name: buffer I don't know what i did wrong.

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C# - Stack Vs Heap In .NET

Oct 13, 2009

In your actual programming experience, how did this knowledge of STACK and HEAP actually rescue you in real life? Any story from the trenches? Or is this concept good for filling up programming books and good for theory?

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Do All Programming Languages Use Static / HEAP & Stack Areas To Store Memory

Apr 9, 2012

Do all programming languages use the Static, HEAP, & Stack areas to store memory? Does understanding this help me with debugging in any way? How do I query or access the memory in .NET would I ever need to do that? Or the memory addresses?What keywords would I type into Google to get more on how the .NET CLR uses memory?I'm learning Java and am trying to compare .NET and Java and how memory management differs and is similiar.

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Reference To The String In The Heap Is Passed Even When You Pass The String ByVal To A Method?

Mar 2, 2011

So strings are reference types right? My understanding is a reference to the string in the heap is passed even when you pass the string ByVal to a method.

String myTestValue = "NotModified";
System.Diagnostics.Debug.Write(myTestValue); /* myTestValue = "NotModified" WTF? *[code].....

And what is going on under the hood? I would have bet my life that the value would have changed....

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Circular Motion In VB?

Dec 24, 2009

I have to make a learning object program for a school project and i am doing it about circular motion and satellite i can get a object to orbit around another object in visual basic, allowing the orbit radius to vary as the user inputs values?

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.net - Circular Dependency Between MODEL And BLL?

Sep 1, 2011

Assuming an architecture as such.MODEL > BLL > DLL

Trying to implement lazy loading in my MODEL I have run into a circular dependency between my MODEL and BLL..Basically imagine a property in my model that I want to implement as follows

Public Readonly Property ProjectCategory As ProjectCategory
If Me._ProjectCategory Is Nothing Then
Me._ProjectCategory = ProjectCategoryBLL.GetProjectCategoryByID(Me._ProjectCategoryID)
End If


I have my MODEL, BLL and DLL in separate projects and because of the fact that my BLL references my model I can not reference my BLL from my model as this would create a circular dependency.

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Draw A Circular Gradient?

Mar 22, 2011

How do I draw a circular gradient like this in

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Working With A Circular Transparency?

Aug 24, 2009

my team is working on an application where we have to have one image which is acting as the base of all the elements on the screen.. and this same image has a transparency in the center. now this centre transparency is supposed to display a picture which will be captured from a web cam.currently everything working fine but the only problem which we are facing is that the picture is not proportionate to what is the actual resolution that it was shot at. it has been stretched from the top and bottom. the reason is that the imagebox which has been used to call this webcam display is a it seems that the team is not being able to use the exact proportions of the image to call it in the picturebox for a reason that the final image needs to be cropped to fit in a simple words, i have a rectangular image and i want to draw a circle over this image. whatever is within the circle should be visible, whatever is outside the circle should be transparent. (a mask needs to be created...)but the only thing is that this circle will first display the image/video from the web camera and only once the picture is clicked, it should show the same picture within this circular area.

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Circular Reference In A TextBox_TextChanged Event?

Jun 10, 2009

I have created a TextBox array where certain cells are assigned a number which I do not want the operator to change either intentionally or inadvertantly.The relevant TextBox cells are identified by their BackColor, (in this case LightBlue)If the cell is changed the original content is immediately assigned to the cell and a relevant message is displayed.My problem is that by changing the value back to its original value I create another TextChanged event and the consequence is that the MsgBox is displayed twice, one after the other.I have avoided the problem by not displaying a message box.  The outward appearance is that the TextBox is not changed at all, which of course is my aim.However I would prefer to display a message box.An example of the scenario is shown below.

Another bewildering fact, (to me), is that in the example below, if the check is not made of the BackColor but instead the value of the TextBox the problem doesn't occur

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
If TextBox1.BackColor = Color.LightBlue Then[code]...

In the example above, if in the Text_Changed event handler the 'Remark' is changed from one 'If' statement to the other the differences in the result can be seen.

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Circular Referencing - Validated Three Lists

Oct 5, 2010

I'm working on creating my own sudoku solver to learn I decided to have an element class which represents a single square in the puzzle. That element then has references to three lists which can be validated (no duplicate numbers). The three lists then would be its corresponding row/column/subGrid. Each list then holds a reference to 9 elements. Thus in my design an element has a reference to a list, which then holds a reference to that same element. Now will allow me to do this so I don't think it is the same issue that I saw when searching for solutions to circular referencing. However, I still wonder whether or not this is bad design.

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Creating A Circular VB Form - 2008?

Jan 31, 2010

Is it possible to create a circular visual basic form. I see plenty of tutorials on how to do this for VB6 but none on Visual Basic Express.

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Disposing Of Objects And Circular References

May 24, 2010

I have a button which opens FormTest. When FormTest opens, it creates an instance of ClassTest and that class instance takes the form instance that called it (FormTest) so that it can perform operations on FormTest from the ClassTest class instance. So i have a form which owns an instance of a class which has a reference to the form.


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DotNetBar Circular Progress Bar - Marquee?

Feb 7, 2012

There is a question that I have from YEARS after working with DotNetBar Components that How do you set the Marquee style of a normal progress bar on the circular one? The circular progress bar from DotNetBar, i want to be clear.There is no "Style" Property and now I really need to know it for a project I'm doing now

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Use Circular Reference In A Calculation In Program?

Sep 1, 2010

I've got a requirement where I need to calculate a value, however also refer to this value when calculating it. So I've got for example[code]...

I can see how this can be achieved in excel using Circular Reference, however I'm not sure how I go about it when using VB.Net. Is there a similar method to create a Circular Reference as in excel or any other way I can possibly work out the TotalValue?

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Make A Circular Portion Of Rectangle Transparent?

Apr 26, 2011

If I were to draw a rectangle with e.Graphics.FillRectangle(), how would I make a circular portion of the rectangle transparent?

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C# - Delegate Event To Form Without Creating Circular Reference

Jun 19, 2012

I have a class that is in an assembly due to being required for other projects that I'm currently working on. One class lets call it Class Factory, creates a group of controls which require click event handlers to be attached, I have algorithms which determine polymorphic behavior based on certain features but that is relatively irrelevant.

Due to the event handler having to open up a specific form that isn't part of my assembly, and that form requiring this "Factory" class. Without creating circular reference is there any way I can essentially "delegate" the handler event for the form to define? As a simple work around I have had to maintain two separate classes, one in the project with the form and one in the assembly.

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.Width = 1500
Dim panel As New Panel
panel.Location = New Point(0, 0)
panel.Size = New Size(1000, 200)
[Code] .....

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Custom Serialization And Circular References, Is There A Clean Solution?

Aug 3, 2010

I'm implementing some custom serialization (to byte array), and have run into a problem handling circular references.Example:

Class A
public MyBs as new List(of B)
End class

Class B
public MyParent as A
public MiscInt1 as integer[code]....

If I know that an instance of B will only ever be serialized through the serialization of an instance of A, then I can handle the setup of the MyParent reference from the instance of A and not even record that information inside the byte buffer for the instance of B.This doesn't feel quite right, but it might be the best solution.

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VS 2005 - Program To Implement Queue Using Circular Array?

Nov 30, 2009

I'm a newbie in visual basic. We have a project in our school in implementing queue using circular array.

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C# - Enable Circular Dependencies In Visual Studio At The Assembly Level?

Jul 3, 2010

So in Visual Studio, you can't have two projects X and Y such that X references Y and Y references X.In general, I can totally understand how having a circular dependency can be problematic, for a variety of reasons.But is it really not possible to compile two projects that are interdependent in this way? It seems to me that it must be possible, since (in my mind -- maybe I'm completely off-base about this) having two mutually dependent assemblies is really not so different from having two mutually dependent classes -- a case which is legal and can be compiled.

It would make sense to me if you said, "two assemblies cannot depend on each other because the compiler could not compile one before the other"; except that it seems you could make the same argument for two classes within the same assembly, and clearly the compiler can deal with this scenario just fine.

Basically the reason I'm asking is not that I have some desperate desire to do this thing that I know is generally ill-advised anyway. Specifically I'm wondering because it would be nice if I could have two projects -- say, MyProjectCS and MyProjectVB -- that existed basically as two mutually dependent parts of a single unit, and were only separate because certain parts were written in C# and other parts were written in VB.NET.

Is it possible to enable this behavior (in Visual Studio, or elsewhere, for that matter)? If it's not possible within any IDE, it it at least theoretically possible, or could mutually dependent assemblies not possibly exist? If it's not even theoretically possible, why not? In other words, how are mutually dependent assemblies different from mutually dependent code within a single assembly?

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Code Organization - .NET Circular Dependency / Duplex Communication Between Projects?

Oct 16, 2011

I have 2 projects


UI references Functionality to call specific functions. Functionality needs to call certain functions that operate UI. This is what I mean by Duplex communication. Is there any way to do this without causing circular dependency?Should there be 1 main project which simply does all the calling acting as a "wrapper" between UI and Functionality?

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Oop - .NET Class Properties Ends Up In Circular References And Through StackOverflow Exception?

Jan 9, 2012

I have 2 classess. Role and User like this

Public Class Role
Public Property RoleID As Integer
Public Property CreatedBy As User


The situation is like when we create roles, we will save who created this role. So i have a CreatedBy Property of type User. Similarly when we create a User, we will mention what role the new user belongs to .So i have a property called "Role" of type "Role". This circular reference giving me StackOverflow exception as its recursive when i create an object of User class.How do i handle this ? should i restucture my entties ? how ?

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C# - Does The CLR Garbage Collection Methodology Mean It's Safe To Throw Circular Object References Around

Feb 3, 2010

I have a theory that the CLR garbage collection mechanism means that I can get away with circular references in my object hierarchy without creating deadlocks for teardown and garbage collection. Is this a safe assumption to make? (Target language VB.NET)

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Double Buffer Or Not To Double Buffer?

Apr 17, 2010

To Double Buffer or not to Double Buffer this is the Question!I have a form with Protected Overrides Sub OnPaint that sets forms background to a gradient fill ,on top of that is a transparent richtext box.
Ok. now here`s the problem ,If i enable forms double buffering the transparent Rtb doesn't flicker when forms resized. but the forms drop shadow does flicker! ,its a boarderless form using CS_DROPSHADOW to draw the drop shadow Now if i disable double buffering the forms drop shadow doesn`t flicker but the transparent Rtb does ,any one have a clue how to get both to work in harmony !

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ASCII To HEX Buffer Converting?

Sep 16, 2009

The reply buffer is in ASCII value...but I need is HEX value.Is there any way that the reply buffer is in hex?

Public Function read_write_string(ByVal devicehandle, ByVal command, ByVal commandlenght) As String
Dim inputReportBuffer(100) As Byte
unManagedBuffer = Marshal.AllocHGlobal(inputReportBuffer.Length)


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Buffer 28 Bytes From The Com Port?

Apr 21, 2010

I have a problem that i cant solve i am trying to buffer 28 bytes from the com port into the array actual_packet_VPS1(30). It works with the counter set to 0 - 15 but doesnt work when we increase the counter size to 0 -28.

Private Sub MSComm5_OnComm(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MSComm5.OnComm
Dim buffer As Object


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How To Double Buffer A Flowlayoutpanel

Jan 12, 2012

I have a need to double buffer a flowlayoutpanel. I have the form set to doublebuffered which is half the story but their is no property in the list to make the flowlayoutpanel do this (although MSDN states that it has this property) how i can set it to true for the panel?

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Playing Video From Buffer?

Apr 29, 2012

Im trying to do a video player but i have to play this video from the buffer, is this possible.. Let me explain you much more complicated,a got a CryptoStream and im decryting the video

While lngBytesProcessed < lngFileLength
'Read file with the input filestream.
intBytesInCurrentBlock = fsInput.Read(bytBuffer, 0, 4096)
'Write output file with the cryptostream.


This code writes my decryted or crypted video to a new file. However, i need to play the video file from the buffer(without copying to a new file), in other way it would be meaningless if i create a decryted file. in other words it would unsecure for me cuz if anyone can locate my temp directorey they can copy my decrypted video files.

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Process The Buffer - EOF Expected

Jul 9, 2011

Dim Fs as FileSystemObject
Dim TS as TextStream
Set Fs = CreateObject("Scripting.FileSystemObject")
Set Ts = fs.OpenTextFile(textFilePath, ForReading, False,
While not Ts.AtEndOfStream
' Process the buffer
I tried to convert into c# but am getting ERROR like EOF expected, what I have to do?

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Streaming To A Buffer And Then Using Data?

Jul 31, 2010

I am using sockets to send a music file from one instance to another. It currently saves the file, but I do not want to be caught up in file-sharing, so I want to "save" it to a buffer, and when it gets to a particular percentage transferred, I want another thread to play the music file, deleting it from the buffer as it plays. I have the code to send it over the network, but I need to know how to keep it in a buffer and not save it as a file.

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VB To .net Conversion Buffer String?

Sep 3, 2011

I've looked and looked + tryed debugging but I'm not getting anywhere fast I'm trying to import a usb radio driver and I'm 99% there. I can turn it on / off and get / set the freq.. but I'm struggling to get the rds name from it. The VB code for the function is


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.net - Make A Packet Using Dim Buffer As Byte()?

Mar 7, 2012

basically I'm sending and receiving both images, strings and files over a client/server connection. I can easily use a protocol for string commands but I cannot distinguish between the incoming data [if data is image or whatever and then follow onward instructions].So how do I make a packet using Dim buffer as byte()?

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Get Double Buffer Function Working

Dec 13, 2011

I've been trying to get the double buffer function working in VB.NET GDI+ for a space invaders game using the following command.[code]But because I am using a separate draw routine attached to a class it doesn't seem to work:[code]The aliens draw correctly but the images are very stuttery and double buffering doesn't seem to work.

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How To Find Socket Buffer Size

Jan 4, 2009

I have connected to a host, but how do I find the correct buffer size? (The Buffer is currently set to 8k (8192))
Dim webget As New Net.Sockets.Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
webget.Connect(host, port)
webget.Send(data, 0, data.Length, SocketFlags.None)
Dim rData(8192) As Byte
webget.Receive(rData, rData.Length, 0)

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Maximum Buffer Length Is Exceeded?

Jul 26, 2011

I see this error page appears in some client access but some client didn't see this.

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Reading Ports To A Buffer To Parse

Nov 15, 2009

I'm currently working on a little software for my GPS and i havent touched VB in about 10 years so I'm trying to figure this out from scratch again pretty much. Anyway, I have this code to get the information from the GPS and parse it, the only problem is that It isn't getting all the code at once and then parsing, it is getting bits and pieces and only getting the RIGHT code from time to time..

Private Sub timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles timer1.Tick


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Search A String Buffer With Nulls (chr(0))?

Sep 25, 2009

I need to search a buffer for a string of characters.The buffer is essentially a binary file (it's an image) and contains lots of chr(0) characters.The string I need to locate also contains chr(0) characters. In fact it is the following string:

chr(100) & chr(0) & chr(0) & chr(163)

This is a marker in the image file for items I need to process.So I though I would do the following:

Dim sFileBuffer as String  ="myimagefile")
Dim sLookFor as String = chr(100) & chr(0) & chr(0) & chr(163)  
Dim iLocation as Integer = sFileBuffer.IndexOf(sLookFor)  

The problem is that, although the characters in sLookFor definitely exist inside of sFileBuffer - IndexOf will always return -1 (not found).I tried the following:

Dim Marker() as Byte = {100, 0, 0 , 163}
Dim sLookFor as String = System.Text.Encoding.UTF8.GetString(Marker)
Dim sFileBuffer as String  ="myimagefile",  Encoding.UTF8)  
Dim iLocation as Integer = sFileBuffer.IndexOf(sLookFor)  

But this appears to only find occurrences of Chr(100) & Chr(0) - not the full 4 character sequence I desire. It appears to see the second Chr(0) as a termination of the search string.I think the sticking point here is the null. Yes - I can string.replace(chr(0), Chr(255)) in both the sLookFor and the sFileBuffer and adjust my search accordingly - but that seems like a mess to me.Is there not a way to search a buffer of binary data? I've tried working with byte arrays - but there appears to be no way to easily search for a sequence of byte values - just individual elements in the array.

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SerialPort DataReceived Buffer Construction?

Jun 15, 2011

I've managed to make an application at home using a serialport emulator and connector that will read text from a file on my desktop send it to com1 and then my connector program will merge com1 with com2. In short my program works at home but when I connect it to my device it appears the data in DataReceived is a fraction of what my simulator setup at home is producing, which apparently is completely normal according to all these threads I've read here. 


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