DSStreamCB

Stream context block structure.

Synopsis

typedef struct DSStreamCB {
   Item creatorTask;
   uint32 creatorSignal;
   int32 creatorStatus;
   Item threadItem;
   void* threadStackBlock;
   Item acquirePort;
   long bufDataSize;
   DSDataBufPtr freeBufHead;
   unsigned long streamFlags;
   uint32 clockOffset;
   uint32 lastValidClock;
   uint32 branchDest;
   Item requestPort;
   uint32 requestPortSignal;
   Item acqReplyPort;
   uint32 acqReplyPortSignal;
   MemPoolPtr dataMsgPool;
   Item subsReplyPort;
   uint32 subsReplyPortSignal;
   MemPoolPtr subsMsgPool;
   DSDataBufPtr filledBufHead;
   DSDataBufPtr filledBufTail;
   long totalBufferCount;
   long currentFreeBufferCount;
   DSRequestMsgPtr endOfStreamMsg;
   int32 repliesPending;
   DSRequestMsgPtr requestMsgHead;
   DSRequestMsgPtr requestMsgTail;
   long numSubscribers;
   DSSubscriber subscriber[DS_MAX_SUBSCRIBERS];
} DSStreamCB,  *DSStreamCBPtr

Description

This data structure contains all the contexts necessary to drive a stream, including a description of all subscribers and the information necessary to manage all memory buffers. One of these data structures exists for each open stream.

Fields

creatorTask: Task to signal when initialization complete.

creatorSignal: Signal to send for synchronous completion.

creatorStatus: Result code for creator.

threadItem: Thread Item for the server process.

threadStackBlock: Pointer to thread's stack memory block.

acquirePort: Acquisition module message port.

bufDataSize: Size of data buffers in BYTES.

freeBufHead: Pointer to list of free data buffers.

streamFlags: Stream state flags.

clockOffset: Offset to get relative stream clock.

lastValidClock: Set when stream stopped.

branchDest: Marker to branching to STRM_GO_INPROGRESS true.

requestPort: Work request message port.

requestPortSignal: Signal for request port.

acqReplyPort: Reply port for data acquisition communications.

acqReplyPortSignal: Signal for data acquisition reply port.

dataMsgPool: Pool of data message blocks.

subsReplyPort: Reply port for subscriber communication.

subsReplyPortSignal: Signal for subscriber reply port.

subsMsgPool: Pool of subscriber message blocks.

filledBufHead: Pointer to list of filled data buffers.

filledBufTail: Pointer to end of list of filled data buffers.

repliesPending: Number of replies needed before replying to request.

requestMsgHead: Pointer to first request message in queue.

requestMsgTail: Pointer to last request message in queue.

numSubscribers: Number of subscribers.

Associated Files

DataStream.h