fr.cnes.sirius.patrius.bodies.bsp.spice

Class SpkFile

java.lang.Object

fr.cnes.sirius.patrius.bodies.bsp.spice.SpkFile

public final class SpkFile
extends Object

Load and unload files for use by the readers. Buffer segments for readers.

Before a file can be read by the S/P-kernel readers, it must be loaded by loadSpkFile, which among other things, loads the file into the DAF system.

Up to MAX_FILES files may be loaded for use simultaneously, and a file only has to be loaded once to become a potential search target for any number of subsequent reads.

Once an SPK file has been loaded, it is assigned a file handle, which is used to keep track of the file internally, and which is used by the calling program to refer to the file in all subsequent calls to SPK routines.

A file may be removed from the list of files for potential searching by unloading it via a call to unloadSpkFile.

SPKSFS performs the search for segments within a file for the S/P-kernel readers. It searches through last-loaded files first. Within a single file, it searches through last-inserted segments first, thus assuming that "newest data is best".

Information on loaded files is used by SPKSFS to manage a buffer of saved segment descriptors and identifiers to speed up access time without having to necessarily perform file reads.

This class is based on the SPKBSR.for file of the SPICE library.

Since:

4.11

Author:

T0281925

Field Summary

Fields

Modifier and Type	Field and Description
static int	ND Number of double precision components in a summary.
static int	NI Number of integer components in a summary.

Method Summary

Modifier and Type	Method and Description
static int	loadSpkFile(String file) Load an ephemeris file for use by the readers.
static boolean	searchSegment(int body, double et, int[] handle, double[] descr, String[] ident) Search through loaded SPK files to find the highest-priority segment applicable to the body and time specified and buffer searched segments in the process, to attempt to avoid re-reading files.
static void	unloadSpkFile(int handle) Unload an ephemeris file so that it will no longer be searched by the readers.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ND

public static final int ND

Number of double precision components in a summary.

See Also:

Constant Field Values

NI

public static final int NI

Number of integer components in a summary.

See Also:

Constant Field Values

Method Detail

loadSpkFile

public static int loadSpkFile(String file)
                       throws IOException,
                              PatriusException

Load an ephemeris file for use by the readers. Return that file's handle, to be used by other SPK routines to refer to the file.

This method is based on the SPKLEF routine of the SPICE library.

Parameters:

file - Name of the file to be loaded

Returns:

the loaded file's handle

Throws:

IOException - if there is problem opening the file

PatriusException - if there is a problem opening or closing the file

unloadSpkFile

public static void unloadSpkFile(int handle)
                          throws PatriusException

Unload an ephemeris file so that it will no longer be searched by the readers.

Based on the SPKUEF routine of the SPICE library

Parameters:

handle - Handle of file to be unloaded

Throws:

PatriusException - if there is problem closing the file

searchSegment

public static boolean searchSegment(int body,
                                    double et,
                                    int[] handle,
                                    double[] descr,
                                    String[] ident)
                             throws PatriusException

Search through loaded SPK files to find the highest-priority segment applicable to the body and time specified and buffer searched segments in the process, to attempt to avoid re-reading files.

Based on the SPKSFS routine from the SPICE library

Parameters:

body - Body ID

et - Ephemeris time

handle - Handle of file containing the applicable segment

descr - Descriptor of the applicable segment

ident - Identifier of the applicable segment

Returns:

a boolean indicating whether or not a segment was found

Throws:

PatriusException - if there is a problem while searching in the file

IOException - if there is a problem while beginning a segment search