Function:		PowerDown()

Description:	Powers down the audio codec chip.

Notes:			Even if the input/output channels are muted, this
				function powers down the audio codec chip in order
				to conserve battery power.

Returns:		Boolean indicating success
-------------------------------------------------------------------*/
void HardwareContext::PowerDown()
{
    StopOutputDMA();
	AudioMute((DMA_CH_OUT | DMA_CH_MIC), TRUE);
}


//############################################ Helper Functions #############################################

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		TransferOutputBuffer()

Description:	Retrieves the next "mixed" audio buffer of data to
				DMA into the output channel.

Returns:		Number of bytes needing to be transferred.
-------------------------------------------------------------------*/
ULONG HardwareContext::TransferOutputBuffer(ULONG NumBuf)
{
    ULONG BytesTransferred = 0;

    PBYTE pBufferStart = m_Output_pbDMA_PAGES[NumBuf];
    PBYTE pBufferEnd = pBufferStart + AUDIO_DMA_PAGE_SIZE;
    PBYTE pBufferLast;

	__try
	{
		pBufferLast = m_OutputDeviceContext.TransferBuffer(pBufferStart, pBufferEnd,NULL);
		BytesTransferred = m_OutBytes[NumBuf] = pBufferLast-pBufferStart;

		// Enable if you need to clear the rest of the DMA buffer
		StreamContext::ClearBuffer(pBufferLast,pBufferEnd);
		if(NumBuf == OUT_BUFFER_A)			// Output Buffer A
		{
			m_OutputDMAStatus &= ~DMA_DONEA;
			m_OutputDMAStatus |= DMA_STRTA;
		}
		else								// Output Buffer B
		{
			m_OutputDMAStatus &= ~DMA_DONEB;
			m_OutputDMAStatus |= DMA_STRTB;
		}
	}
	__except(EXCEPTION_EXECUTE_HANDLER) 
	{
		DEBUGMSG(ZONE_ERROR, (TEXT("WAVDEV2.DLL:TransferOutputBuffer() - EXCEPTION: %d"), GetExceptionCode()));
	}

    return BytesTransferred;
}


/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		TransferOutputBuffers()

Description:	Determines which output buffer (A or B) needs to 
				be filled with sound data.  The correct buffer is
				then populated with data and ready to DMA to the 
				output channel.

Returns:		Boolean indicating success
-------------------------------------------------------------------*/
ULONG HardwareContext::TransferOutputBuffers(DWORD dwDCSR)
{
    ULONG BytesTransferred = 0;

    ULONG BytesTotal;
    DWORD Bits = dwDCSR & (DMA_DONEA|DMA_DONEB|DMA_BIU);

//	RETAILMSG(1,(TEXT("%x\n"),Bits));
	switch (Bits)
    {
    case 0:
    case DMA_BIU:
        // No done bits set- must not be my interrupt
        return 0;
    case DMA_DONEA|DMA_DONEB|DMA_BIU:
        // Load B, then A
        BytesTransferred = TransferOutputBuffer(OUT_BUFFER_B);
        // fall through
    case DMA_DONEA: // This should never happen!
    case DMA_DONEA|DMA_BIU:
		BytesTransferred += TransferOutputBuffer(OUT_BUFFER_A);		// charlie, A => B
        break;
    case DMA_DONEA|DMA_DONEB:
        // Load A, then B
        BytesTransferred = TransferOutputBuffer(OUT_BUFFER_A);
        // charlie
        BytesTransferred += TransferOutputBuffer(OUT_BUFFER_B);
        break;		// charlie
        // fall through
    case DMA_DONEB|DMA_BIU: // This should never happen!
    case DMA_DONEB:
        // Load B
        BytesTransferred += TransferOutputBuffer(OUT_BUFFER_B);		// charlie, B => A
        break;
    }

    // If it was our interrupt, but we weren't able to transfer any bytes
    // (e.g. no full buffers ready to be emptied)
    // and all the output DMA buffers are now empty, then stop the output DMA
    BytesTotal = m_OutBytes[OUT_BUFFER_A]+m_OutBytes[OUT_BUFFER_B];

	if (BytesTotal==0)
    {
		StopOutputDMA();
    }
    return BytesTransferred;
}


/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		TransferInputBuffer()

Description:	Retrieves the chunk of recorded sound data and inputs
				it into an audio buffer for potential "mixing".

Returns:		Number of bytes needing to be transferred.
-------------------------------------------------------------------*/
ULONG HardwareContext::TransferInputBuffer(ULONG NumBuf)
{
    ULONG BytesTransferred = 0;

    PBYTE pBufferStart = m_Input_pbDMA_PAGES[NumBuf];
    PBYTE pBufferEnd = pBufferStart + AUDIO_DMA_PAGE_SIZE;
    PBYTE pBufferLast;

	__try
	{
		pBufferLast = m_InputDeviceContext.TransferBuffer(pBufferStart, pBufferEnd,NULL);
		BytesTransferred = m_InBytes[NumBuf] = pBufferLast-pBufferStart;

		if(NumBuf == IN_BUFFER_A)			// Input Buffer A
		{
			m_InputDMAStatus &= ~DMA_DONEA;
			m_InputDMAStatus |= DMA_STRTA;
		}
		else								// Input Buffer B
		{
			m_InputDMAStatus &= ~DMA_DONEB;
			m_InputDMAStatus |= DMA_STRTB;
		}

	}
	__except(EXCEPTION_EXECUTE_HANDLER) 
	{
		DEBUGMSG(ZONE_ERROR, (TEXT("WAVDEV2.DLL:TransferInputBuffer() - EXCEPTION: %d"), GetExceptionCode()));
	}

    return BytesTransferred;
}


/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		TransferInputBuffers()

Description:	Determines which input buffer (A or B) needs to 
				be filled with recorded sound data.  The correct 
				buffer is then populated with recorded sound data
				from the input channel.

Returns:		Boolean indicating success
-------------------------------------------------------------------*/
ULONG HardwareContext::TransferInputBuffers(DWORD dwDCSR)
{
    ULONG BytesTransferred=0;
    DWORD Bits = dwDCSR & (DMA_DONEA|DMA_DONEB|DMA_BIU);

    switch (Bits)
    {
    case 0:
    case DMA_BIU:
        // No done bits set- must not be my interrupt
        return 0;
    case DMA_DONEA|DMA_DONEB|DMA_BIU:
        // Load B, then A
        BytesTransferred = TransferInputBuffer(IN_BUFFER_B);
        // fall through
    case DMA_DONEA: // This should never happen!
    case DMA_DONEA|DMA_BIU:
        // Load A
        BytesTransferred += TransferInputBuffer(IN_BUFFER_A);
        break;
    case DMA_DONEA|DMA_DONEB:
        // Load A, then B
        BytesTransferred = TransferInputBuffer(IN_BUFFER_A);
		BytesTransferred += TransferInputBuffer(IN_BUFFER_B);
		break;
        // fall through
    case DMA_DONEB|DMA_BIU: // This should never happen!
    case DMA_DONEB:
        // Load B
        BytesTransferred += TransferInputBuffer(IN_BUFFER_B);
        break;
    }

    // If it was our interrupt, but we weren't able to transfer any bytes
    // (e.g. no empty buffers ready to be filled)
    // Then stop the input DMA
    if (BytesTransferred==0)
    {
        StopInputDMA();
    }
    return BytesTransferred;
}


void HardwareContext::InterruptThread()
{
    ULONG InputTransferred, OutputTransferred;
	BOOL dmaInterruptSource = 0;

    // Fast way to access embedded pointers in wave headers in other processes.
	SetProcPermissions((DWORD)-1);

    while(TRUE)
    {
		WaitForSingleObject(m_hAudioInterrupt, INFINITE);
		dmaInterruptSource = 0;
		//----- 1. Grab the lock -----
		Lock();

		__try
		{

			//----- 3. Determine the interrupt source (input DMA operation or output DMA operation?) -----
			//----- NOTE:	Often, platforms use two separate DMA channels for input/output operations but
			//				have the OAL return SYSINTR_AUDIO as the interrupt source.  If this is the case,
			//				then the interrupt source (input or output DMA channel) must be determined in
			//				this step.

			if( s2440INT->INTMSK & (1 << IRQ_DMA1) ){
				dmaInterruptSource |= DMA_CH_MIC;								// Input DMA is supported...
			    //----- 2. Acknowledge the DMA interrupt -----
			    InterruptDone(m_dwSysintrInput);
			}
			
			if( s2440INT->INTMSK & (1 << IRQ_DMA2) ){
				dmaInterruptSource |= DMA_CH_OUT;								// Output DMA is supported...
			    //----- 2. Acknowledge the DMA interrupt -----
			    InterruptDone(m_dwSysintrOutput);
			}
						
           
            //----- 4. Handle any interrupts on the input source -----
			//		   NOTE: The InterruptDone() call below automatically clears the interrupt.
			if ((dmaInterruptSource & DMA_CH_MIC) != 0)
			{
				//----- Determine which buffer just completed the DMA transfer -----
				if(m_InputDMAStatus & DMA_BIU)
				{
					m_InputDMAStatus &= ~DMA_STRTB;							// Buffer B just completed...
					m_InputDMAStatus |= DMA_DONEB;

					m_InputDMAStatus &= ~DMA_BIU;							// Buffer A is in use
					SELECT_AUDIO_DMA_INPUT_BUFFER_B();
					DEBUGMSG(ZONE_FUNCTION,(TEXT("1\n")));
				}else
				{
					m_InputDMAStatus &= ~DMA_STRTA;							// Buffer A just completed...
					m_InputDMAStatus |= DMA_DONEA;

					m_InputDMAStatus |= DMA_BIU;							// Buffer B is in use
					SELECT_AUDIO_DMA_INPUT_BUFFER_A();
					DEBUGMSG(ZONE_FUNCTION,(TEXT("2\n")));
				}
				
				//----- 6. Retrieve the next chunk of recorded data from the non-playing buffer -----
				InputTransferred = TransferInputBuffers(m_InputDMAStatus);			
			}

			//----- 7. Handle any interrupts on the output source -----
			//		   NOTE: The InterruptDone() call below automatically clears the interrupt.
			if ((dmaInterruptSource & DMA_CH_OUT) != 0)
			{	
				//----- Determine which buffer just completed the DMA transfer -----
				if(m_OutputDMAStatus & DMA_BIU)
				{
					m_OutputDMAStatus &= ~DMA_STRTB;						// Buffer A just completed...
					m_OutputDMAStatus |= DMA_DONEB;

					m_OutputDMAStatus &= ~DMA_BIU;							// Buffer B is in use
					
					while((g_pDMAregs->DSTAT2&0xfffff)==0);
					SELECT_AUDIO_DMA_OUTPUT_BUFFER_B();		// charlie. B => A
				}else
				{
					m_OutputDMAStatus &= ~DMA_STRTA;						// Buffer B just completed...
					m_OutputDMAStatus |= DMA_DONEA;

					m_OutputDMAStatus |= DMA_BIU;							// Buffer A is in use
					
					while((g_pDMAregs->DSTAT2&0xfffff)==0);
					SELECT_AUDIO_DMA_OUTPUT_BUFFER_A();		// charlie. B => A
				}
				//----- 9. Fill the non-playing buffer with the next chunk of audio data to play -----
				OutputTransferred = TransferOutputBuffers(m_OutputDMAStatus);			
			}

		}
		__except(EXCEPTION_EXECUTE_HANDLER) 
		{
			DEBUGMSG(ZONE_ERROR, (TEXT("WAVDEV2.DLL:InterruptThread() - EXCEPTION: %d"), GetExceptionCode()));
		}

		//----- 10. Give up the lock ----- 
		Unlock();
	}  
}


/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		AudioMute()

Description:	Mutes/unmutes the specified audio channel.

Notes:			If both audio channels are MUTED, then the chip 
				is powered down to conserve battery life.  
				Alternatively, if either audio channel is unMUTED, 
				the chip is powered up.

Returns:		Boolean indicating success
-------------------------------------------------------------------*/
BOOL HardwareContext::AudioMute(DWORD channel, BOOL bMute)
{
	static DWORD dwActiveChannel = 0;
	return(TRUE);
}


void CallInterruptThread(HardwareContext *pHWContext)
{
    pHWContext->InterruptThread();
}