Conference vmszoo::rms_openvms

  Well, the file itself is not a monster.  In fact, in terms of real-world
  files, it is trivial in size.  The problem is simply that it describes
  itself as stream with no delimiters.

  Since you know that it really contains fixed 80-byte records
  (which divides evenly into the total # bytes), you can just
  reset the file attributes on OpenVMS to match the reality of its 
  contents as follows:

  $ SET FILE/ATTR=(RFM=fix,MRS=80,LRL=80) filespec
  
<< Also, it exceeds the physical limits which are specified for COBOL 
<< programs by quite a lot.
  
  I sure hope you mean the record size here and not the file size.
   
  -- Elinor

Re .1

>  I sure hope you mean the record size here and not the file size.
   
    The record size.

   As an alternative to processing a disk file...

   If you know there's nothing in this file but data, and you know that
   each record occupies 80 bytes, then set your PGFLQUOTA and your local
   VIRTUALPAGECNT (assuming this is not V7.0 or later on OpenVMS Alpha),
   sys$crmpsc-map this file as the backing storage file for a private
   section, use the memory management to page-fault the file data into
   memory, and then access the contents of the section directly.  (Using
   this technique, you will see reasonable performance levels, too. :-)

   (And as mentioned, 28 megabytes isn't particularly large by local
   standards -- one of the local files used quite regularly here in
   OpenVMS is well over 1,100,000 blocks; over 550 megabytes.  One
   of the folks tells me that a major file at the CSC is presently
   over 9,600,000 blocks; almost 5 gigabytes.  And files that must
   span multiple disk volumes are definitely around, via volume sets
   or via striping...)

   The attached program uses sys$create and "CIF" -- it will create the
   backing file if not found -- and you may want to use sys$open without
   this option.  And as the attached program is an example, and it maps
   the file into memory twice as a demonstration -- and you likely won't
   want to do this...

	--

#include <descrip.h>
#include <lib$routines.h>
#include <psldef.h>
#include <rms.h>
#include <secdef.h>
#include <ssdef.h>
#include <starlet.h>
#include <stdio.h>
#include <string.h>
#include <stsdef.h>
#include <unixlib.h>

#define MAXACCLEN 16

struct ItemList3
    {
    short int ItemLength;
    short int ItemCode;
    void *ItemBuffer;
    void *ItemRetLen;
    };
struct RmsFileContext
    {
    struct FAB fab;
    struct NAM nam;
    char rss[NAM$C_MAXRSS];
    short max_rec_siz;
    char *data_buffer;
    };
#define P0SPACE ((void*)0x0200)
#define BOGUSMAX 10

RmsFileOpen( struct FAB *fab, char *FileName, char *DefFileName )
    {
    int RetStat;

    *fab = cc$rms_fab;

    fab->fab$l_alq = 10;
    fab->fab$b_fac = 0;
    fab->fab$l_fop = FAB$M_UFO | FAB$M_CIF;
    fab->fab$b_shr = FAB$M_UPI | FAB$M_SHRPUT | FAB$M_SHRGET | FAB$M_SHRUPD;

    fab->fab$l_fna = FileName;
    fab->fab$b_fns = strlen( FileName );
    fab->fab$l_dna = DefFileName;
    fab->fab$b_dns = strlen( DefFileName );

    /*
    // Attempt to open the file...
    */
    RetStat = sys$create( fab, 0, 0 );
    if ( !$VMS_STATUS_SUCCESS( RetStat ) )
	return RetStat;

    return RetStat;
    }

main()
    {
    int RetStat;
    struct ItemList3 ItmLst[10];
    $DESCRIPTOR( SecDsc, "FACNAM_GLOBAL_SECTION_NAME" );
    int i;
    void *InAdr1[2] = {P0SPACE,P0SPACE};
    void *RetAdr1[2] = {NULL,NULL};
    void *InAdr2[2] = {P0SPACE,P0SPACE};
    void *RetAdr2[2] = {NULL,NULL};
    struct FAB Fab1, Fab2;
    struct insec
	{
	int Bogus[BOGUSMAX];
	} *Sec1, *Sec2;

    /*
    //	Create and open, and map the global section...
    */
    RetStat = RmsFileOpen( &Fab1, "BOGUS", "SYS$SCRATCH:.TMP" );
    if (!$VMS_STATUS_SUCCESS( RetStat ))
	lib$signal( RetStat );
    RetStat = sys$crmpsc( InAdr1, RetAdr1, PSL$C_USER, 
	SEC$M_EXPREG | SEC$M_WRT | SEC$M_DZRO | SEC$M_GBL,
	&SecDsc,
	0, 0, Fab1.fab$l_stv, 1, 0, 0, 0 );
    if (!$VMS_STATUS_SUCCESS( RetStat ))
	lib$signal( RetStat );

    /*
    //	Create and open, and map the global section again...
    */
    RetStat = RmsFileOpen( &Fab2, "BOGUS", "SYS$SCRATCH:.TMP" );
    if (!$VMS_STATUS_SUCCESS( RetStat ))
	lib$signal( RetStat );
    RetStat = sys$crmpsc( InAdr2, RetAdr2, PSL$C_USER, 
	SEC$M_EXPREG | SEC$M_WRT | SEC$M_GBL,
	&SecDsc,
	0, 0, Fab2.fab$l_stv, 1, 0, 0, 0 );
    if (!$VMS_STATUS_SUCCESS( RetStat ))
	lib$signal( RetStat );

    /*
    //	Write the information to one "window"...
    //	... read the data back from the other.
    */
    Sec1 = RetAdr1[0];
    Sec2 = RetAdr2[0];
    for ( i = 0; i < BOGUSMAX; i++)
	Sec1->Bogus[i] = i;
    for ( i = 0; i < BOGUSMAX; i++)
	printf( "Bogus[%d] = %d\n", i, Sec2->Bogus[i] );

    return SS$_NORMAL;
    }