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Synchronous Data Stream (SDS)

Synchronous Data Stream transfer interfaces for recording real-world data and for replay of captured data in Arm Virtual Hardware (AVH) simulation. Supports development of ML and DSP applications.

The following interfaces are defined:

Synchronous Data Stream using circular buffer

Stream data is written to and read from a circular buffer allocated in RAM. Event callback function which is triggered on data threshold reached can be registered.

The API is defined in sds.h. It features the following functions:

  • sdsOpen: Opens a stream with user provided buffer and specified thresholds for data events. It returns the stream identifier which is used in other functions specifying a stream.
  • sdsClose: Closes the specified stream.
  • sdsRegisterEvents: Registers an event callback function for the specified stream with event mask and user argument.
  • sdsWrite: Writes data to the specified stream and returns the number of bytes written (no overflow). Optional callback with event SDS_EVENT_DATA_HIGH is executed at the end when number of bytes in the stream is above or equal to the configured threshold.
  • sdsRead: Reads data from the specified stream and returns the number of bytes read. Optional callback with event SDS_EVENT_DATA_LOW is executed at the end when number of bytes in the stream is below or equal to the configured threshold.
  • sdsClear: Clears data in specified stream.
  • sdsGetCount: Gets the number of bytes in the stream.

Function calls shall be non-blocking and thread-safe.

The following reference implementation is provided in sds.c. It features:

  • user configurable number of streams (default: 16 streams)

Synchronous Data Stream using Input/Output

Stream data is written to an Output device or read from an Input device. Input/Output device can be a File System, STDIO, Socket, ...

The API is defined in sdsio.h. It features the following functions:

  • sdsioInit: Initializes the Input/Output interface.
  • sdsioUnInit: Un-initializes the Input/Output interface.
  • sdsioOpen: Opens a named I/O stream for read or write operation. It returns the I/O stream identifier which is used in other functions specifying an I/O stream.
  • sdsioClose: Closes the specified I/O stream.
  • sdsioWrite: Writes data to the specified I/O stream and returns the number of bytes written (no overflow).
  • sdsioRead: Reads data from the specified I/O stream and returns the number of bytes read.
  • sdsioEndOfStream: Checks if end of stream has been reached and returns a nonzero value if end of stream.

Function calls are typically blocking and shall be thread-safe.

Synchronous Data Stream Recorder

Stream data is recorded (written to an Output device). Output device can be a File System, STDIO, Socket, ...

The API is defined in sds_rec.h. It features the following functions:

  • sdsRecInit: Initializes the recorder interface and registers an optional event callback function.
  • sdsRecUnInit: Un-initializes the recorder interface.
  • sdsRecOpen: Opens a named recorder stream with user provided buffer and specified threshold to trigger I/O write. It returns the recorder stream identifier which is used in other functions specifying a recorder stream.
  • sdsRecClose: Closes the specified recorder stream.
  • sdsRecWrite: Writes a record with data and timestamp to the specified recorder stream and returns the number of data bytes written (no overflow).

The function sdsRecWrite call shall be non-blocking where other function calls are typically blocking. All function calls except sdsRecInit/UnInit shall be thread-safe.

Optional event callback function is executed with event:

  • SDS_REC_EVENT_IO_ERROR: when an I/O error occurs during writing to the output device.

The following reference implementation is provided in sds_rec.c. It features:

  • user configurable number of streams (default: 8 streams, max: 30)
  • user configurable maximum record size (default: 1024 bytes)
  • uses SDS buffer (non-blocking sdsRecWrite) and SDSIO
  • uses a thread for reading from SDS buffer and writing to blocking SDSIO

Synchronous Data Stream Player

Stream data is played back (read from an Input device). Input device can be a File System, STDIO, Socket, ...

The API is defined in sds_play.h. It features the following functions:

  • sdsPlayInit: Initializes the player interface and registers an optional event callback function.
  • sdsPlayUninit: Un-initializes the player interface.
  • sdsPlayOpen: Opens a named player stream with user provided buffer and specified threshold to trigger I/O read. It returns the player stream identifier which is used in other functions specifying a player stream.
  • sdsPlayClose: Closes the specified player stream.
  • sdsPlayRead: Reads a record with data and timestamp from the specified player stream and returns the number of data bytes read.
  • sdsPlayGetSize: Gets the number of data bytes in the record.
  • sdsPlayEndOfStream: Checks if end of stream has been reached and returns a nonzero value if end of stream.

The function sdsPlayRead call shall be non-blocking where other function calls are typically blocking. All function calls except sdsPlayInit/UnInit shall be thread-safe.

Optional event callback function is executed with event:

  • SDS_PLAY_EVENT_IO_ERROR: when an I/O error occurs during reading from the input device.