Acquisition context structure.

typedef struct AcqContext {
 Item creatorTask;
 uint32 creatorSignal;
 int32 creatorStatus;
 char* fileName;
 ItemPoolPtr ioReqItemPoolPtr;
 Item threadItem;
 void* threadStackBlock;
 Item requestPort;
 uint32 requestPortSignal;
 Item ioDoneReplyPort;
 uint32 ioDoneReplyPortSignal;
 DataAcqMsgPtr requestQueue;
 DataAcqMsgPtr abortQueue;
 DataAcqMsgPtr dataQueueHead;
 DataAcqMsgPtr dataQueueTail;
 Boolean fEOFWasSent;
 long offset;
 BlockFile blockFile;
 Item dsReqReplyPort;
 uint32 dsReqReplyPortSignal;
 uint32 subscriberPortSignal;
 Item subscriberPort;
 DSStreamCBPtr streamCBPtr;
 MarkerChunkPtr markerChunk;
} AcqContext, *AcqContextPtr

The context block containing state and environment variables for a data acquisition thread.

• creatorTask Item of the task that created the acquisition thread, usually the task to signal that the acquisition thread has been initialized.

• creatorSignal Signal to send for synchronous completion.

• creatorStatus Initialization status code of acquisition thread, usually returned to the creator task for error checking.

• fileName Pointer to the character string that is the name of the file from which the task acquires data.

• ioReqItemPoolPtr Pointer to the pool of ioReqItem items allocated by the data buffers for the thread. See DSDataBuf{} for more details.

• threadItem Item of the acquisition thread.

• threadStackBlock Pointer to the stack memory block allocated to the acquisition thread.

• requestPort DataStreamer message port through which the thread receives acquisition requests.

• requestPortSignal Signal associated with requestPort.

• ioDoneReplyPort Message port for I/O completion messages.

• ioDoneReplyPortSignal Signal associated with ioDoneReplyPort.

• requestQueue List of outstanding I/O request messages.

• abortQueue List of outstanding I/O request messages that are considered `aborted'.

• dataQueueHead Head of requests waiting for ioreqitems.

• dataQueueTail Tail of requests waiting for ioreqitems.

• fEOFWasSent Indicates whether an end of file character (EOF) has been sent to the acquisition thread: TRUE if one has been sent, FALSE if not.

• offset Location in the block file at which the acquisition thread is currently reading blocks of data. The offset is calculated, in blocks, as an offset from the beginning of the file.

• blockFile Block file from which the acquisition thread acquires blocks of data.

• dsReqReplyPort Reply port for requests to streamer.

• dsReqReplyPortSignal Signal for replies to streamer requests

• subscriberPortSignal Signal for receipt of subscriber messages.

• subscriberPort Message port for our data type.

• streamCBPtr Stream control block of connected stream.

• markerChunk Pointer to copy of most recent translation table.

DataAcq.h

''%%DSDataBuf%%''