| ekopw_c |
|
Table of contents
Procedure
ekopw_c ( EK, open file for writing )
void ekopw_c ( ConstSpiceChar * fname,
SpiceInt * handle )
AbstractOpen an existing E-kernel file for writing. Required_ReadingEK KeywordsEK FILES UTILITY Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- fname I Name of EK file. handle O Handle attached to EK file. Detailed_Input
fname is the name of an existing E-kernel file to be
opened for write access.
Detailed_Output
handle is the DAS file handle of the EK designate by
`fname'. This handle is used to identify the file
to other EK routines.
Parameters
SPICE_DAS_FTSIZE
is the maximum number of DAS files that a user can
have open simultaneously. This includes any files used
by the DAS system.
See the header file SpiceDAS.h for the actual value of
this parameter.
Exceptions
1) If the indicated file cannot be opened, an error is signaled
by a routine in the call tree of this routine.
2) If the indicated file has the wrong architecture version, an
error is signaled by a routine in the call tree of this
routine.
3) If an I/O error occurs while reading or writing the indicated
file, the error is signaled by a routine in the call tree of
this routine.
4) If the `fname' input string pointer is null, the error
SPICE(NULLPOINTER) is signaled.
5) If the `fname' input string has zero length, the error
SPICE(EMPTYSTRING) is signaled.
FilesSee the EK Required Reading for a discussion of the EK file format. Particulars
This routine should be used to open an EK existing file for write
access.
Opening an EK file with this routine makes the EK accessible to
the following CSPICE EK access routines, all of which modify
the target EK file:
Begin segment:
ekbseg_c
Append, insert, delete records:
ekappr_c
ekinsr_c
ekdelr_c
Add column entries:
ekacec_c
ekaced_c
ekacei_c
Update existing column entries:
ekucec_c
ekuced_c
ekucei_c
Execute fast write:
ekifld_c
ekffld_c
ekaclc_c
ekacld_c
ekacli_c
An EK opened for write access is also accessible for reading.
The file may be accessed by the CSPICE EK readers
ekrcec_c
ekrced_c
ekrcei_c
and summary routines:
eknseg_c
ekssum_c
An EK opened for write access cannot be queried. To make an EK
available to the EK query system, the file must be loaded via
furnsh_c or eklef_c, rather than by this routine. See the EK Required
Reading for further information.
Examples
The numerical results shown for this example may differ across
platforms. The results depend on the SPICE kernels used as
input, the compiler and supporting libraries, and the machine
specific arithmetic implementation.
1) The following program demonstrates how to create a new EK and
add data to a character column in a given record within the
file, how to re-open the file for write access and update the
data, and how to read the data from it.
Example code begins here.
/.
Program ekopw_ex1
./
#include <stdio.h>
#include <string.h>
#include "SpiceUsr.h"
int main( )
{
/.
Local parameters.
./
#define EKNAME "ekopw_ex1.bdb"
#define IFNAME "Test EK"
#define TABLE "CHR_DATA"
#define CVLEN 10
#define DECLEN 201
#define MAXVAL 4
#define NCOLS 2
#define NROWS 6
#define NRESVC 0
/.
Local variables.
./
SpiceChar cdecls [NCOLS] [DECLEN];
SpiceChar cnames [NCOLS] [SPICE_EK_CSTRLN];
SpiceChar cvals [MAXVAL][CVLEN];
SpiceInt handle;
SpiceInt i;
SpiceInt nvals;
SpiceInt recno;
SpiceInt segno;
SpiceBoolean isnull;
/.
Open a new EK file. For simplicity, we won't
reserve space for the comment area, so the
number of reserved comment characters is zero.
The constant IFNAME is the internal file name.
./
ekopn_c ( EKNAME, IFNAME, NRESVC, &handle );
/.
Set up the table and column names and declarations
for the CHR_DATA segment. We'll index all of
the columns.
./
strcpy( cnames[0], "CHR_COL_1" );
strcpy( cdecls[0], "DATATYPE = CHARACTER*(*), "
"INDEXED = TRUE, NULLS_OK = TRUE" );
strcpy( cnames[1], "CHR_COL_2" );
strcpy( cdecls[1], "DATATYPE = CHARACTER*(9), "
"SIZE = VARIABLE, NULLS_OK = TRUE" );
/.
Start the segment.
./
ekbseg_c ( handle, TABLE, NCOLS, SPICE_EK_CSTRLN,
cnames, DECLEN, cdecls, &segno );
for ( i = 0; i < NROWS; i++ )
{
ekappr_c ( handle, segno, &recno );
isnull = ( i == 1 );
sprintf ( cvals[0], "%d", (int)i );
ekacec_c ( handle, segno, recno, cnames[0],
1, CVLEN, cvals, isnull );
/.
Array-valued columns follow.
./
sprintf ( cvals[0], "%d", (int)(10*i) );
sprintf ( cvals[1], "%d", (int)(10*i + 1) );
sprintf ( cvals[2], "%d", (int)(10*i + 2) );
sprintf ( cvals[3], "%d", (int)(10*i + 3) );
ekacec_c ( handle, segno, recno, cnames[1],
4, CVLEN, cvals, isnull );
}
/.
End the file.
./
ekcls_c ( handle );
/.
Open the EK for write access.
./
ekopw_c ( EKNAME, &handle );
/.
Negate the values in the odd-numbered records
using the update routines.
./
for ( i = 1; i < NROWS; i = i+2 )
{
recno = i;
isnull = ( i == 1 );
sprintf ( cvals[0], "%d", (int)(-i) );
ekucec_c ( handle, segno, recno, cnames[0],
1, CVLEN, cvals, isnull );
/.
Array-valued columns follow.
./
sprintf ( cvals[0], "%d", (int)(-10*i) );
sprintf ( cvals[1], "%d", (int)(-(10*i + 1)) );
sprintf ( cvals[2], "%d", (int)(-(10*i + 2)) );
sprintf ( cvals[3], "%d", (int)(-(10*i + 3)) );
ekucec_c ( handle, segno, recno, cnames[1],
4, CVLEN, cvals, isnull );
}
/.
Close the file.
./
ekcls_c ( handle );
/.
Open the created file. Show the values added.
./
ekopr_c ( EKNAME, &handle );
for ( i = 0; i < NROWS; i++ )
{
ekrcec_c ( handle, segno, i, cnames[0],
CVLEN, &nvals, cvals, &isnull );
if ( ! isnull )
{
printf( "Data from column: %s\n", cnames[0] );
printf( " record number: %d\n", (int)i );
printf( " values : %s\n", cvals[0] );
printf( " \n" );
}
else
{
printf( "Record %d flag is NULL.\n", (int)i );
printf( " \n" );
}
/.
Array-valued columns follow.
./
ekrcec_c ( handle, segno, i, cnames[1],
CVLEN, &nvals, cvals, &isnull );
if ( ! isnull )
{
printf( "Data from column: %s\n", cnames[1] );
printf( " record number: %d\n", (int)i );
printf( " values : %s %s %s %s\n",
cvals[0], cvals[1], cvals[2], cvals[3] );
printf( " \n" );
}
}
/.
Close the file.
./
ekcls_c ( handle );
return ( 0 );
}
When this program was executed on a Mac/Intel/cc/64-bit
platform, the output was:
Data from column: CHR_COL_1
record number: 0
values : 0
Data from column: CHR_COL_2
record number: 0
values : 0 1 2 3
Record 1 flag is NULL.
Data from column: CHR_COL_1
record number: 2
values : 2
Data from column: CHR_COL_2
record number: 2
values : 20 21 22 23
Data from column: CHR_COL_1
record number: 3
values : -3
Data from column: CHR_COL_2
record number: 3
values : -30 -31 -32 -33
Data from column: CHR_COL_1
record number: 4
values : 4
Data from column: CHR_COL_2
record number: 4
values : 40 41 42 43
Data from column: CHR_COL_1
record number: 5
values : -5
Data from column: CHR_COL_2
record number: 5
values : -50 -51 -52 -53
Note that the second record does not appear due to setting the
`isnull' flag to SPICETRUE for that record. The odd value record
numbers have negative values as a result of the update calls.
After run completion, a new EK exists in the output directory.
Restrictions
1) No more than SPICE_DAS_FTSIZE DAS files may be opened simultaneously.
See the header file SpiceDAS.h for the value of SPICE_DAS_FTSIZE.
Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) Version
-CSPICE Version 1.0.2, 02-AUG-2021 (JDR)
Edited the header to comply with NAIF standard. Added complete
code example.
Added SPICE_DAS_FTSIZE parameter description. Updated index entry.
-CSPICE Version 1.0.1, 09-JAN-2002 (NJB)
Documentation change: instances of the phrase "fast load"
were replaced with "fast write."
-CSPICE Version 1.0.0, 25-MAY-1999 (NJB)
Index_Entriesopen existing EK for writing |
Fri Dec 31 18:41:06 2021