/*++

Copyright (c) 1995 Microsoft Corporation

Module Name:

    timer.h

Abstract:

    Represintaion for NT timers, to allow callback at IRQL PASSIVE_LEVEL.

Author:

    Erez Haba (erezh) 31-Mar-96

Revision History:

--*/

#ifndef __TIMER_H
#define __TIMER_H

//---------------------------------------------------------
//
//  class CTimer
//
//---------------------------------------------------------

class CTimer {
public:
    CTimer();

    BOOL SetTo(LARGE_INTEGER& liTime);
    BOOL Cancel();

    void GetCurrentTime(LARGE_INTEGER& liTime);
    bool SetCallback(PDEVICE_OBJECT pDevice, PIO_WORKITEM_ROUTINE pCallback, PVOID pContext);
    void GetCallback(PIO_WORKITEM_ROUTINE * ppCallback, PVOID * ppContext) const;
    LONG Busy(LONG ulBusy);

private:
    static void NTAPI DefferedRoutine(PKDPC, PVOID, PVOID, PVOID);


private:
    PIO_WORKITEM_ROUTINE m_pCallback;
    PVOID m_pContext;
    KTIMER m_timer;
    KDPC m_DPC;
    PIO_WORKITEM m_pWorkItem;
    LONG m_ulBusy;
};

//---------------------------------------------------------
//
//  IMPLEMENTATION
//
//---------------------------------------------------------

inline CTimer::CTimer() :
    m_ulBusy(0),
    m_pWorkItem(NULL)
{
}

inline BOOL CTimer::SetTo(LARGE_INTEGER& liTime)
{
    return KeSetTimer(&m_timer, liTime, &m_DPC);
}

inline BOOL CTimer::Cancel()
{
    return KeCancelTimer(&m_timer);
}

inline void CTimer::GetCurrentTime(LARGE_INTEGER& liTime)
{
    KeQuerySystemTime(&liTime);
}

inline bool CTimer::SetCallback(PDEVICE_OBJECT pDevice, PIO_WORKITEM_ROUTINE pCallback, PVOID pContext)
{
    m_pWorkItem = IoAllocateWorkItem(pDevice);
    if (m_pWorkItem == NULL)
    {
        return false;
    }

    m_pCallback = pCallback;
    m_pContext = pContext;

    KeInitializeTimer(&m_timer);
    KeInitializeDpc(&m_DPC, DefferedRoutine, m_pWorkItem);

    return true;
}

inline void CTimer::GetCallback(PIO_WORKITEM_ROUTINE * ppCallback, PVOID * ppContext) const
{
    (*ppCallback) = m_pCallback;
    (*ppContext) = m_pContext;
}

inline LONG CTimer::Busy(LONG ulBusy)
{
    return InterlockedExchange(&m_ulBusy, ulBusy);
}

#endif // __TIMER_H