rtstream.cpp File Reference

#include "rtminiport.h"
#include "rtstream.h"

Include dependency graph for rtstream.cpp:

Go to the source code of this file.

Macros
#define	STR_MODULENAME   "AC97 RT Stream: "

Functions
NTSTATUS	CreateAC97MiniportWaveRTStream (OUT CAC97MiniportWaveRTStream **RTStream)
	STDMETHODIMP_ (NTSTATUS) CAC97MiniportWaveRTStream
_Use_decl_annotations_	STDMETHODIMP_ (VOID) CAC97MiniportWaveRTStream

Macro Definition Documentation

STR_MODULENAME

#define STR_MODULENAME   "AC97 RT Stream: "

Definition at line 11 of file rtstream.cpp.

Function Documentation

CreateAC97MiniportWaveRTStream()

NTSTATUS CreateAC97MiniportWaveRTStream

(

OUT CAC97MiniportWaveRTStream **

RTStream

)

Definition at line 37 of file rtstream.cpp.

{
    PAGED_CODE ();
 
    DOUT (DBG_PRINT, ("[CreateAC97MiniportWaveRTStream]"));
 
    //
    // This is basically like the macro at stdunk with the change that we
    // don't cast to interface unknown but to interface CAC97MiniportWaveRTStream.
    //
    *RTStream = new (NonPagedPool, PoolTag) CAC97MiniportWaveRTStream (NULL);
    if (*RTStream)
    {
        (*RTStream)->AddRef ();
        return STATUS_SUCCESS;
    }
 
    return STATUS_INSUFFICIENT_RESOURCES;
}

STDMETHODIMP_() [1/2]

STDMETHODIMP_

(

NTSTATUS

)

Definition at line 187 of file rtstream.cpp.

{
    PAGED_CODE ();
 
    //
    // Make sure complete samples fit into the buffer.
    //
    if( size <= size % (NumberOfChannels * 2) )
    {
        return STATUS_UNSUCCESSFUL;
    }
    size -= size % (NumberOfChannels * 2);
 
    //
    // Validate that we're going to actually allocate a real amount of memory.
    //
    if (0 == size)
    {
        DOUT (DBG_WARNING, ("Zero byte memory allocation attempted."));
        return STATUS_UNSUCCESSFUL;
    }
 
    //
    // Allocate the buffer.
    // The AC97 has problems playing 6ch data on page breaks (a page is 4096 bytes
    // and doesn't contain complete samples of 6ch 16bit audio data). We therefore
    // allocate contiguous memory that fits complete 6ch 16bit samples, however,
    // contiguous memory is a lot more expensive to get and you might not get it
    // at all. Useing non-contiguous memory (AllocatePagesForMdl) is therefore much
    // better if your HW does support it. It is highly recommended to build future
    // HW so that it can map a variable amount of pages, that it can cycle through
    // the scatter gather list automatically and that it handles that case where
    // samples are "split" between 2 pages.
    //
    PHYSICAL_ADDRESS    low;
    PHYSICAL_ADDRESS    high;
 
    low.QuadPart = 0;
    high.HighPart = 0, high.LowPart = MAXULONG;
    PMDL audioBufferMdl = PortStream->AllocateContiguousPagesForMdl (low, high, size);
 
    //
    // Check if the allocation was successful.
    //
    if (!audioBufferMdl)
    {
        DOUT (DBG_WARNING, ("[AllocateAudioBuffer] Can not allocate RT buffer."));
        return STATUS_UNSUCCESSFUL;
    }
 
    //
    // We got our memory. Program the BDL (scatter gather list) now.
    //
    //
    // Note that when you use AllocatePagesForMdl that you might get less memory
    // back. In this case you need to check the byte count of the Mdl and continue
    // with that size.
    //
 
    //
    // Store the information for portcls so that the buffer can be mapped to
    // the client.
    //
    *userModeBuffer = audioBufferMdl;
    *bufferSize = size;
    *bufferOffset = 0;
    *cacheType = MmCached;
 
    //
    // Program the BDL
    //
    for (UINT loop = 0; loop < MAX_BDL_ENTRIES; loop++)
    {
        BDList[loop].dwPtrToPhyAddress = PortStream->GetPhysicalPageAddress (audioBufferMdl, 0).LowPart;
        BDList[loop].wLength = (WORD)size/2;
        if ((loop == MAX_BDL_ENTRIES / 2) || (loop == MAX_BDL_ENTRIES - 1))
            BDList[loop].wPolicyBits = IOC_ENABLE;
        else
            BDList[loop].wPolicyBits = 0;
    }
 
    return STATUS_SUCCESS;
}

STDMETHODIMP_() [2/2]

_Use_decl_annotations_ STDMETHODIMP_

(

VOID

)

Definition at line 287 of file rtstream.cpp.

{
    PAGED_CODE ();
 
    UNREFERENCED_PARAMETER(Size);
 
    //
    // Just delete the MDL that was allocated with AllocateContiguousPagesForMdl.
    //
    if (NULL != Mdl)
    {
        PortStream->FreePagesFromMdl (Mdl);
    }
}