Getting values from the Noticeboard

Values can be accessed either by copying to and from the user's buffer or else directly to and from the noticeboard. Both methods are illustrated here.

      INTEGER   ACTBYTES                ! Actual number of bytes stored
      INTEGER   POINTER                 ! Pointer to MATRIX data
      CHARACTER*20  CONF                ! Configuration to be read

Get current value of MATRIX. We expect the actual number of bytes to be at least 16.

      NBS_GET_VALUE (MATID,0,16,MATRIX,ACTBYTES,STATUS)
      IF (ACTBYTES .LT. 16) THEN
         panic
      ENDIF

Again, reading character strings is slightly different,

      NBS_GET_CVALUE (MATID,0,CONF,     ! Use the portable routine
                     ACTBYTES,STATUS)
      NBS_GET_VALUE (MATID,0,LEN(CONF), ! or the VMS specific call
 %REF(CONFIG),ACTBYTES,STATUS) ! using %REF

Alternatively get a pointer to the actual data in the noticeboard.

      NBS_GET_POINTER (MATID,POINTER,STATUS)
      MATRIX_OP(%VAL(POINTER),STATUS)

• The second parameter to NBS_GET_VALUE and NBS_GET_CVALUE is a byte offset. You can use non-zero offsets to get a slice of the data associated with an item.
• The length of the string passed into NBS_GET_CVALUE serves the same purpose as the third argument to NBS_GET_VALUE -- ie. it limits the amount of data that can be read.
• It is not an NBS error if an item contains fewer bytes than are being asked for.
• When accessing data directly via pointer, no checks are possible and the modified count is not (and could not be) accessed.