LowLevelWriteNoPoll

Writes raw bytes directly to a device without going through the formatted I/O write buffer.

virtual HRESULT LowLevelWriteNoPoll(BYTE* pBuf, long cbDesired, long* pcbActual = NULL, bool bAddTrailing = true, long lTimeout = CUR_TIMEOUT) override;	

virtual HRESULT LowLevelWriteNoPoll(SAFEARRAY* pBuf, long cbDesired = -1, long* pcbActual = NULL, bool bAddTrailing = true, long lTimeout = CUR_TIMEOUT) override;

Parameters

pBuf: [int] Array of bytes to write to the device.
cbDesired: [in] Number of bytes to write to the device. If pBuf is a SAFEARRAY and cbDesired is -1, then the entire contents of the SAFEARRAY are sent to the device.
pcbActual: [out] Actual number of bytes written to the device. pcbActual may be set to NULL if the caller is not interested in knowing the actual number of bytes written.
bAddTrailing: [in] true to have the trailing characters specified by the SetTrailingForWrites function automatically added to pBuf before sending to the device.
lTimeout: [in] I/O timeout value in milliseconds.

Return Value

Returns S_OK if successful, otherwise a failure HRESULT.

Remarks

This function behaves identically to the LowLevelWrite function except that the device is not polled for errors after the data is written.

Caution
It is critical that these low-level functions not be intermixed with buffered I/O functions in a sequence of operations, such as a set of calls implementing a single driver method. The buffered I/O functions assume that all data read from or sent to the device passes through the I/O buffer, and intermixing these calls with low-level functions that directly access the device can produce incorrect results and/or I/O errors.

Caution

It is critical that these low-level functions not be intermixed with buffered I/O functions in a sequence of operations, such as a set of calls implementing a single driver method. The buffered I/O functions assume that all data read from or sent to the device passes through the I/O buffer, and intermixing these calls with low-level functions that directly access the device can produce incorrect results and/or I/O errors.

Example

The following example demonstrates use of the LowLevelWriteNoPoll function.

C++

Copy

// CoAcme4321.cpp
STDMETHODIMP Acme4321::IAcme4321_Configure(SAFEARRAY* psaData)
{
  HRESULT hr = S_OK;

  // Write 1000 bytes from psaData
  hr = io.LowLevel.LowLevelWriteNoPoll(psaData, 1000);

  return hr;
}

Other Resources

LowLevelWrite

LowLevelWriteString

LowLevelWriteStringNoPoll