Procedure

     DASRWR ( DAS, read/write records )

     SUBROUTINE DASRWR ( HANDLE,
    .                    RECNO,
    .                    RECC,
    .                    RECD,
    .                    RECI,
    .                    FIRST,
    .                    LAST,
    .                    DATAD,
    .                    DATAI,
    .                    DATAC   )

Abstract

     Read and write DAS physical records.

Required_Reading

     DAS

Keywords

     ASSIGNMENT
     DAS
     FILES

Declarations

     IMPLICIT NONE

     INTEGER               NWD
     PARAMETER           ( NWD    =  128 )

     INTEGER               NWI
     PARAMETER           ( NWI    =  256 )

     INTEGER               NWC
     PARAMETER           ( NWC    = 1024 )

     INTEGER               HANDLE
     INTEGER               RECNO
     CHARACTER*(*)         RECC
     DOUBLE PRECISION      RECD    ( NWD )
     INTEGER               RECI    ( NWI )
     INTEGER               FIRST
     INTEGER               LAST
     DOUBLE PRECISION      DATAD   ( * )
     INTEGER               DATAI   ( * )
     CHARACTER*(*)         DATAC

     INTEGER               BUFSZD
     PARAMETER           ( BUFSZD = 10 )

     INTEGER               BUFSZI
     PARAMETER           ( BUFSZI = 10 )

     INTEGER               BUFSZC
     PARAMETER           ( BUFSZC = 10 )

Brief_I/O

     VARIABLE  I/O  ENTRY POINTS
     --------  ---  --------------------------------------------------
     HANDLE     I   RRD, RRI, RRC, WRD, WRI, WRC, URD, URI, URC
     RECNO      I   RRD, RRI, RRC, WRD, WRI, WRC, URD, URI, URC
     RECC       I   WRC
     RECD       I   WRD
     RECI       I   WRI
     FIRST      I   RRD, RRI, RRC, URD, URI, URC
     LAST       I   RRD, RRI, RRC, URD, URI, URC
     DATAD      O   RRD, URD
     DATAI      O   RRI, URI
     DATAC      O   RRC, URC
     NWD        P   RRD, WRD, URD
     NWI        P   RRI, WRI, URI
     NWC        P   RRC, WRC, URC
     BUFSZD     P   RRD, WRD, URD
     BUFSZI     P   RRI, WRI, URI
     BUFSZC     P   RRC, WRC, URC

Detailed_Input

     See the entry points for a discussion of their inputs.

Detailed_Output

     See the entry points for a discussion of their outputs.

Parameters

     NWD      is the number of DPs in a single DAS record
              containing DPs.

     NWI      is the number of integers in a single DAS record
              containing integers.

     NWC      is the number of characters in a single DAS record
              containing characters.

     BUFSZD,
     BUFSZI,
     BUFSZC   are, respectively, the number of records in the
              data buffers for double precision, integer, and
              character records.

Exceptions

     1)  If this routine is called directly, the error
         SPICE(BOGUSENTRY) is signaled.

     2)  See the entry points for discussions of their exceptions.

Files

     See the description of the argument HANDLE in the headers of
     the entry points for a description of files accessed by this
     set of routines.

Particulars

     This suite of routines provides buffered read and write access to
     DAS files. The purpose of this feature is to increase the
     performance of application programs that access DAS files: in
     particular, repeated reads from or writes to a given record
     should be relatively fast, because the contents of the most
     recently accessed records are buffered in memory. Thus DASRWR
     and its entry points act as a miniature virtual memory system for
     DAS files.

     These routines are intended primarily for use by other SPICELIB
     routines; users' application programs will not normally need to
     call these routines. Writing to a DAS file with these routines
     demands a particularly circumspect approach: it's quite easy to
     end up with something other than a DAS file if one misuses the
     routines.

     The entry points of DASRWR support writing, reading, and updating
     the records in a DAS file. The distinction between writing and
     updating is that any record may be written (as long as the record
     belongs to a file open for writing), but only existing records
     may be updated.  `Writing' a record sets the values of all of
     the elements of the record, while a subrange of the elements of an
     existing record may be `updated'.

     For each of these three operations, there are three DAS routines,
     one for each supported data type. The names of the routines are

        -- For writing:     DASWRC,  DASWRD,  DASWRI
        -- For updating:    DASURC,  DASURD,  DASURI
        -- For reading:     DASRRC,  DASRRD,  DASRRI

     Users should note that, unlike in the case of SPICELIB's DAF
     routines, the DAS routines buffer data that is written as well
     as data that is read. Consequently a DAS file does not
     necessarily yet contain, at any moment, all of the data that
     has been written to it by the DASWRx or DASURx routines. The
     written data that is buffered is written out when the need
     to buffer additional data requires it, and also when the user
     commands the closure of a file that has been written. So, at
     the time a DAS file is closed, the contents of the physical file
     do reflect what has been `written' to the file by the DASWRx and
     DASURx entry points.

     At any time, an application program can force the DAS system to
     write to a DAS file any buffered records maintained for that
     file. The entry point DASWBR (DAS, write buffered records)
     provides this capability.

     DASRWR contains three record buffers: one of character type,
     one of double precision type, and one of integer type. Each
     buffer has enough room for an integer number of records. The
     sizes of the buffers are parameterized and can be increased if
     necessary. When contemplating the revision of the buffer
     sizes selected by NAIF, SPICELIB users should take note of the
     following points:

        -- Changing values of parameters in NAIF subroutines may cause
           a maintenance burden for the users of the modified NAIF
           code, since any changes made to a SPICELIB routine will have
           to be made to any new version of that routine released by
           NAIF in a later version of SPICELIB.

        -- The effect of buffer size on the speed with which an
           application executes is highly dependent on the specific
           application. In some cases, increasing the buffer sizes
           may slow the application down.

Examples

     See the entry points for examples specific to those routines.

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)
     K.R. Gehringer     (JPL)
     B.V. Semenov       (JPL)
     W.L. Taber         (JPL)

Version

    SPICELIB Version 2.1.0, 07-OCT-2021 (NJB) (JDR)

        Added initializers for record buffers.

        Edited the headers of DASRWR and all its entry points to comply
        with NAIF standard.

        Cleaned up the $Revisions history.

    SPICELIB Version 2.0.0, 05-FEB-2015 (NJB)

        Upgraded to support handle manager integration and
        reading of non-native files.

    SPICELIB Version 1.1.1, 10-FEB-2014 (BVS)

        Added description of NWD, NWI, and NWC to the $Parameters
        and $Brief_I/O sections of the header.

    SPICELIB Version 1.1.0, 17-NOV-1995 (NJB)

        Made modifications to the DASRRx routines to enhance
        efficiency. Removed references to the function RETURN.

        Removed weird spaces from ENTRY statements.

    SPICELIB Version 1.0.1, 28-OCT-1993 (KRG)

        Removed references to specific DAS file open routines in the
        $Detailed_Input section of the header for each entry point.
        This was done in order to minimize documentation changes if the
        DAS open routines ever change.

    SPICELIB Version 1.0.0, 30-JUN-1992 (NJB) (WLT)