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From: J.R. Heisey J.R. on 7 Apr 2010 11:53
Greetings,

Apparently post to this group with Outlook Express does not work anymore.

I could not find a group that was specific to Microsoft's WinUsb driver.
Please refer me.

* Using a background thread to process packets from the interrupt endpoint.
* Background thread calls WinUsb_ReadPipe() then waits on the passed in
event object.
* On returning from the wait function my ReadCompletion() function is
called. Function is below.
* This code is implemented in a native x86 DLL.
* When this DLL is used by a particular in-house DotNet application the
buffer m_InterruptReadBuffer
does not contain the data even though m_uInterruptReadCount contains the
data length.
* Does not appear to happen when executing from a native x86 application.
* Note the use of two buffers.
* I would like an explanation and how to correct this behavior so that I
don't
need the hack code.

Anyone from Microsoft listening?

Thanks,
J.R. Heisey
Synaptic, Inc.
Lead Software Engineer

void InterruptReadCompletion()

{

if (WinUsb_GetOverlappedResult(m_usbHandle,

&m_ovInterruptRead,


&m_uInterruptReadCount[m_uInterruptBufferIndex],
TRUE))

{

DWORD uBufferIndex = m_uInterruptBufferIndex;

// hack that works because data is aways ASCII

while (m_InterruptReadBuffer[uBufferIndex] == 0)

{

// Need this wait loop because the buffer does not contain the data
on return of WinUsb_GetOverlappedResult()

}

// Swap buffer so we can get the next on started during the dispatch.

m_uInterruptBufferIndex = m_uInterruptBufferIndex == 1 ? 0 : 1;

InterruptReadBegin(); // calls WinUsb_ReadPipe() again.

// using two buffers else the single buffer can get corrupted after this
point

if (m_uInterruptReadCount[uBufferIndex] != 0)

{

DispatchInterruptCallback((char
*)&m_InterruptReadBuffer[uBufferIndex][0],

m_uInterruptReadCount[uBufferIndex]);

}

}

}




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