purge.cpp

这个是串口驱动程序开发包

/*++

Abstract:

    This module contains the code that is very specific to purge
    operations in the serial driver

--*/

#include "precomp.h"

NTSTATUS KdSerialDevice::StartPurge()

/*++

Routine Description:

    Depending on the mask in the current irp, purge the interrupt
    buffer, the read queue, or the write queue, or all of the above.

Return Value:

    Will return STATUS_SUCCESS always.  This is reasonable
    since the DPC completion code that calls this routine doesn't
    care and the purge request always goes through to completion
    once it's started.

--*/

{
    KdIrp NewIrp;

    do {
        ULONG Mask;

        Mask = *((PULONG) m_CurrentPurgeIrp.SystemBuffer());

        if (Mask & SERIAL_PURGE_TXABORT) 
        {
            KillAllReadsOrWrites(
                &m_WriteQueue,
                &m_CurrentWriteIrp
                );
            KillAllReadsOrWrites(
                &m_WriteQueue,
                &m_CurrentXoffIrp
                );
        }

        if (Mask & SERIAL_PURGE_RXABORT) 
        {
            KillAllReadsOrWrites(
                &m_ReadQueue,
                &m_CurrentReadIrp
                );
        }

        if (Mask & SERIAL_PURGE_RXCLEAR) 
        {
            // Clean out the interrupt buffer.
            //
            // Note that we do this under protection of the
            // the drivers control lock so that we don't hose
            // the pointers if there is currently a read that
            // is reading out of the buffer.
            m_ControlLock.Lock();
            m_KdInterrupt.SynchronizeExecution((KDIRQ_SYNC_CALLBACK) PurgeInterruptBuff);
            m_ControlLock.Release();
        }

        m_CurrentPurgeIrp.Status() = STATUS_SUCCESS;
        m_CurrentPurgeIrp.Information() = 0;

        GetNextIrp(
            &m_CurrentPurgeIrp,
            &m_PurgeQueue,
            &NewIrp,
            TRUE
            );

    } while (NewIrp);

    return STATUS_SUCCESS;
}

BOOLEAN KdSerialDevice::PurgeInterruptBuff()

/*++

Routine Description:

    This routine simply resets the interrupt (typeahead) buffer.

    NOTE: This routine is being called from KeSynchronizeExecution.

Return Value:

    Always false.

--*/

{
    // The typeahead buffer is by definition empty if there
    // currently is a read owned by the isr.
    if (m_ReadBufferBase == m_InterruptReadBuffer) 
    {
        m_CurrentCharSlot = m_InterruptReadBuffer;
        m_FirstReadableChar = m_InterruptReadBuffer;
        m_LastCharSlot = m_InterruptReadBuffer +
                             (m_BufferSize - 1);
        m_CharsInInterruptBuffer = 0;

        HandleReducedIntBuffer();
    }

    return FALSE;
}