125 lines
2.8 KiB
C++
125 lines
2.8 KiB
C++
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// Copyright (c) 1996-1999 Microsoft Corporation
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/* CPhaseLockClock
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*/
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#include <windows.h>
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#include <windowsx.h>
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#include <stdio.h>
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#include "dmusicc.h"
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#include "dmusics.h"
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#include "plclock.h"
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#include "misc.h"
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#define MILS_TO_REF 10000
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CPhaseLockClock::CPhaseLockClock()
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{
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m_rfOffset = 0;
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}
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void CPhaseLockClock::Start(REFERENCE_TIME rfMasterTime, REFERENCE_TIME rfSlaveTime)
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/* When the clock starts, it needs to mark down the
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difference between the time it is given and its concept of time.
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*/
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{
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m_rfOffset = rfMasterTime - rfSlaveTime;
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}
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void CPhaseLockClock::GetSlaveTime(REFERENCE_TIME rfSlaveTime, REFERENCE_TIME *prfTime)
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/* Convert the passed time to use the same base as the master clock.
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*/
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{
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rfSlaveTime += m_rfOffset;
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*prfTime = rfSlaveTime;
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}
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void CPhaseLockClock::SetSlaveTime(REFERENCE_TIME rfSlaveTime, REFERENCE_TIME *prfTime)
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{
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rfSlaveTime -= m_rfOffset;
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*prfTime = rfSlaveTime;
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}
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void CPhaseLockClock::SyncToMaster(REFERENCE_TIME rfSlaveTime, REFERENCE_TIME rfMasterTime)
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/* SyncToTime provides the needed magic to keep the clock
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in sync. Since the clock uses its own clock (rfSlaveTime)
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to increment, it can drift. This call provides a reference
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time which the clock compares with its internal
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concept of time. The difference between the two is
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considered the drift. Since the sync time may increment in
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a lurching way, the correction has to be subtle.
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So, the difference between the two is divided by
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100 and added to the offset.
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*/
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{
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rfSlaveTime += m_rfOffset;
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rfSlaveTime -= rfMasterTime; // Find difference between calculated and expected time.
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rfSlaveTime /= 100; // Reduce in magnitude.
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m_rfOffset -= rfSlaveTime; // Subtract that from the original offset.
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}
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CSampleClock::CSampleClock()
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{
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m_dwStart = 0;
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m_dwSampleRate = 22050;
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}
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void CSampleClock::Start(IReferenceClock *pIClock, DWORD dwSampleRate, DWORD dwSamples)
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{
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REFERENCE_TIME rfStart;
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m_dwStart = dwSamples;
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m_dwSampleRate = dwSampleRate;
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if (pIClock)
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{
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pIClock->GetTime(&rfStart);
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m_PLClock.Start(rfStart,0);
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}
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}
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void CSampleClock::SampleToRefTime(LONGLONG llSampleTime,REFERENCE_TIME *prfTime)
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{
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llSampleTime -= m_dwStart;
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llSampleTime *= MILS_TO_REF;
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llSampleTime /= m_dwSampleRate;
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llSampleTime *= 1000;
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m_PLClock.GetSlaveTime(llSampleTime, prfTime);
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}
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LONGLONG CSampleClock::RefTimeToSample(REFERENCE_TIME rfTime)
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{
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m_PLClock.SetSlaveTime(rfTime, &rfTime);
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rfTime /= 1000;
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rfTime *= m_dwSampleRate;
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rfTime /= MILS_TO_REF;
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return rfTime + m_dwStart;
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}
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void CSampleClock::SyncToMaster(LONGLONG llSampleTime, IReferenceClock *pIClock)
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{
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llSampleTime -= m_dwStart;
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llSampleTime *= MILS_TO_REF;
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llSampleTime /= m_dwSampleRate;
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llSampleTime *= 1000;
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if (pIClock)
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{
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REFERENCE_TIME rfMasterTime;
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pIClock->GetTime(&rfMasterTime);
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m_PLClock.SyncToMaster(llSampleTime, rfMasterTime);
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}
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}
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