EVT_SERCX2_SYSTEM_DMA_TRANSMIT_CANCEL_DRAIN_FIFO callback function (sercx.h)
The EvtSerCx2SystemDmaTransmitCancelDrainFifo event callback function is called by version 2 of the serial framework extension (SerCx2) to cancel a previous request to drain the transmit FIFO in the serial controller hardware.
Syntax
EVT_SERCX2_SYSTEM_DMA_TRANSMIT_CANCEL_DRAIN_FIFO EvtSercx2SystemDmaTransmitCancelDrainFifo;
BOOLEAN EvtSercx2SystemDmaTransmitCancelDrainFifo(
[in] SERCX2SYSTEMDMATRANSMIT SystemDmaTransmit
)
{...}
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.
Return value
The EvtSerCx2SystemDmaTransmitCancelDrainFifo function returns TRUE if it successfully cancels the pending drain request, and the serial controller driver can guarantee that it will not call the SerCx2SystemDmaTransmitDrainFifoComplete method to notify SerCx2 that the FIFO is drained. Otherwise, this function returns FALSE to indicate that the driver has already called or is about to call SerCx2SystemDmaTransmitDrainFifoComplete.
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 EvtSerCx2SystemDmaTransmitCancelDrainFifo function if the serial controller has a hardware FIFO (or similar buffering mechanism) to hold transmit data. If your driver implements this function, it must also implement the EvtSerCx2SystemDmaTransmitDrainFifo and EvtSerCx2SystemDmaTransmitPurgeFifo event callback functions.
After SerCx2 calls the EvtSerCx2SystemDmaTransmitDrainFifo event callback function to request that the serial controller driver drain the transmit FIFO, SerCx2 might call the EvtSerCx2SystemDmaTransmitCancelDrainFifo function to cancel the pending drain request before the FIFO finishes draining. For example, SerCx2 might call the EvtSerCx2SystemDmaTransmitCancelDrainFifo function if the client cancels the pending write (IRP_MJ_WRITE) request, or if the write request times out.
For more information, see SerCx2 System-DMA-Transmit Transactions.
Examples
To define an EvtSerCx2SystemDmaTransmitCancelDrainFifo 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 EvtSerCx2SystemDmaTransmitCancelDrainFifo callback function that is named MySystemDmaTransmitCancelDrainFifo, use the EVT_SERCX2_SYSTEM_DMA_TRANSMIT_CANCEL_DRAIN_FIFO function type, as shown in this code example:
EVT_SERCX2_SYSTEM_DMA_TRANSMIT_CANCEL_DRAIN_FIFO MySystemDmaTransmitCancelDrainFifo;
Then, implement your callback function as follows:
_Use_decl_annotations_
BOOLEAN
MySystemDmaTransmitCancelDrainFifo(
SERCX2SYSTEMDMATRANSMIT SystemDmaTransmit
)
{...}
The EVT_SERCX2_SYSTEM_DMA_TRANSMIT_CANCEL_DRAIN_FIFO 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_CANCEL_DRAIN_FIFO 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. |
See also
EvtSerCx2SystemDmaTransmitDrainFifo