Set The Buffer (2nd Pramater Declared Below ) In The WriteFile Function?
Jan 16, 2012
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In VB read HID, we detect the device as above successfully. (STM32L)
When sending a 8 bytes command to the device,
type Reg Value Index Length
40 48 00 00 00 00 01 00
with the nNumberOfBytesToWrite=2 (3rd paramater declared below), how to set the Buffer (2nd pramater declared below ) in the WriteFile function? Size of Buffer is within the limitation of OutputReportByteLength(=nNumberOfBytesToWrite).
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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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Dec 15, 2011
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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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May 21, 2010
Why might my GetRawData declared function return a correct value when called from my VB.NET application, but return zero when called from my ASP.NET page?The code is exactly the same except for class type difference (Form / Page) and calling event handler (Form1_Load, Page_Load).
Note: In the actual code, #DLL# and #RAWDATAFILE# are both absolute filenames to my DLL and raw data file respectively.
Note: The DLL file was not created by Visual Studio.
Form1.vb
Public Class Form1
Declare Auto Function GetRawData Lib "#DLL#" (ByVal filename() As Byte, _
ByVal byteArray() As Byte, _
[code]....
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Aug 15, 2009
Module Exercise
Private Function SetMembershipLevel()
Dim MemberAge
[code].....
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Apr 19, 2010
I have written the following Sub in moduleFunctions to call in any form. But it gives an error: "Name 'txtVNO' is not declared" & "Name 'txtVNM' is not declared"
Public Sub txt_Clear()
txtVNO.Text = ""
txtVNM.Text = ""
End Sub
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Nov 5, 2009
I want to be able have the class autofire a function when it is first declared. In my example it would be to load from a file all the constant variables for use in the program.
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Jan 12, 2012
In VB read HID, we detect the device successfully. When sending a 8 bytes command to the device,
type Reg Value Index Length 40 48 00 00 00 00 01 00
With the OutputReportlength=2, how to set the send buffer in the WriteFile function?
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Sep 3, 2010
I am using CreateFile, WriteFile and ReadFile API calls to write some data to a USB device. The code I have works perfectly on 32 bit systems. CreateFile gets a handle to the device, pass that handle and some data to WriteFile and read from that handle with ReadFile.My problem is, the same code does not work on a 64 bit system. The error returned from WriteFile is 6, The handle is invalid. I've checked the handle for validity on the CreateFile call and it is a valid handle. A call to LastDLLError() returns 0 after CreateFile.The "file" is being opened for overlapped communication and the overlapped init calls are also returning their proper values.is there some sort of different consideration I need to make because it's a 64 bit system? A different flag? A different call altogether?
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May 22, 2009
I'm currently using an unmanaged library written in C++ and imported via <DLLImport()> to access a dos virtual device driver, and that works fine. However, I'd like to be able to do this via my .NET application (without requiring an accompanying DLL). So, I'm trying to write to the virtual dos device using the kernel32 API and WriteFile, however I receive the error: "Attempted to read or write protected memory."
Mapping to the device with DefineDosDevice and CreateFile (also in the kernel32 API) works fine and returns a valid file handle, however when I attempt to write to the file it fails. I've even tried marshaling the data to an unmanaged block of memory using InteropServices (AllocHGlobal and StructureToPtr) and then writing it from there, however I still receive the same error.
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Apr 18, 2012
I'm working on a site that I've inherited that's built with ASP.Net, which I'm only slightly familiar with. One of the pages allows for a link to a document (word or pdf) that, when clicked on, prompts the user to save or open the file, but does not reveal the true path of the file. This way it prevents users from pasting a url to a file - the link is to an aspx file that checks for a valid session, and then retrieves the file.
Anyway, because there's a lot of legacy code, I need to do this with a bunch of static htm files as well, however these files need to be displayed rather than prompting the user to save them, which is what happens now. I tried changing the content type to application/text, application/html, text/html, etc. and that didn't work, then tried adding a response header of content-disposition inline. When I do that, build, and try linking to the file, I get a couple of runtime exceptions:
[FormatException: Input string was not in a correct format.]
Microsoft.VisualBasic.CompilerServices.Conversions.ParseDecimal(String Value, NumberFormatInfo NumberFormat) +206
Microsoft.VisualBasic.CompilerServices.Conversions.ToLong(String Value) +110
[Code].....
Do I have to do something with an htmlwriter object or something? Can't I just have it open a new browser window with the file displaying or does it have to prompt the user if used in this way??
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Jun 6, 2011
Oddly enough, I've worked around this issue, but it's still annoying me. I worked around it by sending too-long writes, with padded zeroes; the code works but sends a few hundred unnecessary bytes. Specifically, I need to send exactly 992-byte packets instead of 7 or 19-byte packets
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Jan 22, 2010
I have textbox with vbscript, user could type integers, then hit return key, KeyUp event for return would trigge theWriteFile()being called for com port to write string to the device, if Ihit return key slow, I would get 0bytewritten for WriteFile(), timeout happening basically,if I hit return keyquick,
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Jan 26, 2011
Yesterday I started my first DLL project which is for ArabicMessageBox that will allow arabic programmers to display there message in totally Arabic message.My project contain one Form only, and the basic code that I use is:
Public Overridable Function Show(ByVal APrompt As String) As MsgBoxResult
mLoad(APrompt, MsgBoxStyle.OkOnly, "")
Me.ShowDialog()
[code]....
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Feb 24, 2011
The following is a screenshot of the problem: What can I do?
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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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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?
Code:
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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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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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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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.
[code]....
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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Jul 9, 2011
Dim Fs as FileSystemObject
Dim TS as TextStream
Set Fs = CreateObject("Scripting.FileSystemObject")
Set Ts = fs.OpenTextFile(textFilePath, ForReading, False,
TristateUseDefault)
While not Ts.AtEndOfStream
Buffer=Ts.ReadLine
' Process the buffer
Wend
Ts.Close
Fs.Close
I tried to convert into c# but am getting ERROR like EOF expected, what I have to do?
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Jul 31, 2010
I am using VB.net 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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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
[Code]...
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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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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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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.
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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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Jul 26, 2011
I see this error page appears in some client access but some client didn't see this.
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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
[Code]....
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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 = system.io.file.readalltext("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 = system.io.file.readalltext("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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