EVT_SERCX2_SYSTEM_DMA_TRANSMIT_INITIALIZE_TRANSACTION callback function (sercx.h)

Article
02/22/2024

The EvtSerCx2SystemDmaTransmitInitializeTransaction event callback function is called by version 2 of the serial framework extension (SerCx2) to prepare the serial controller driver to perform a system-DMA-transmit transaction.

Syntax

EVT_SERCX2_SYSTEM_DMA_TRANSMIT_INITIALIZE_TRANSACTION EvtSercx2SystemDmaTransmitInitializeTransaction;

void EvtSercx2SystemDmaTransmitInitializeTransaction(
  [in] SERCX2SYSTEMDMATRANSMIT SystemDmaTransmit,
  [in] ULONG Length
)
{...}

Parameters

[in] SystemDmaTransmit

A SERCX2SYSTEMDMATRANSMIT handle to a system-DMA-transmit object. The serial controller driver previously called the SerCx2SystemDmaTransmitCreate method to create this object.

[in] Length

The number of bytes to be transferred in the system-DMA-transmit transaction.

Return value

None

Remarks

Your serial controller driver can, as an option, implement this function. If implemented, the driver registers the function in the SerCx2SystemDmaTransmitCreate call that creates the system-DMA-transmit object.

Your driver should implement an EvtSerCx2SystemDmaTransmitInitializeTransaction function if it needs to initialize the serial controller and associated hardware in preparation for a new system-DMA-transmit transaction. SerCx2 calls this function, if it is implemented, before a system-DMA-transmit transaction starts. In response to this call, the serial controller driver must call the SerCx2SystemDmaTransmitInitializeTransactionComplete method to notify SerCx2 after the initialization is finished.

For more information, see SerCx2 System-DMA-Transmit Transactions.

Examples

To define an EvtSerCx2SystemDmaTransmitInitializeTransaction callback function, you must first provide a function declaration that identifies the type of callback function you're defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it's a requirement for writing drivers for the Windows operating system.

For example, to define an EvtSerCx2SystemDmaTransmitInitializeTransaction callback function that is named MySystemDmaTransmitInitializeTransaction, use the EVT_SERCX2_SYSTEM_DMA_TRANSMIT_INITIALIZE_TRANSACTION function type, as shown in this code example:

EVT_SERCX2_SYSTEM_DMA_TRANSMIT_INITIALIZE_TRANSACTION  MySystemDmaTransmitInitializeTransaction;

Then, implement your callback function as follows:

_Use_decl_annotations_
VOID
  MySystemDmaTransmitInitializeTransaction(
    SERCX2SYSTEMDMATRANSMIT  SystemDmaTransmit,
    ULONG Length
    )
  {...}

The EVT_SERCX2_SYSTEM_DMA_TRANSMIT_INITIALIZE_TRANSACTION function type is defined in the Sercx.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the Use_decl_annotations annotation to your function definition. The Use_decl_annotations annotation ensures that the annotations that are applied to the EVT_SERCX2_SYSTEM_DMA_TRANSMIT_INITIALIZE_TRANSACTION function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for KMDF Drivers. For more information about Use_decl_annotations, see Annotating Function Behavior.

Requirements

Requirement	Value
Minimum supported client	Available starting with Windows 8.1.
Target Platform	Desktop
Header	sercx.h
IRQL	Called at IRQL <= DISPATCH_LEVEL.