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Table of contents
Procedure
FURNSH ( Furnish a program with SPICE kernels )
ENTRY FURNSH ( FILE )
Abstract
Load one or more SPICE kernels into a program.
Required_Reading
KERNEL
Keywords
UTILITY
Declarations
CHARACTER*(*) FILE
INTEGER FILSIZ
PARAMETER ( FILSIZ = 255 )
Brief_I/O
VARIABLE I/O DESCRIPTION
-------- --- --------------------------------------------------
FILE I SPICE kernel file (text or binary).
FILSIZ P Maximum file name length.
Detailed_Input
FILE is a SPICE kernel file. The file may be either binary
or text. If the file is a binary SPICE kernel it will
be loaded into the appropriate SPICE subsystem. If
FILE is a SPICE text kernel it will be loaded into the
kernel pool. If FILE is a SPICE meta-kernel containing
initialization instructions (through use of the
correct kernel pool variables), the files specified in
those variables will be loaded into the appropriate
SPICE subsystem.
The SPICE text kernel format supports association of
names and data values using a "keyword = value"
format. The keyword-value pairs thus defined are
called "kernel variables."
While any information can be placed in a text kernel
file, the following string valued kernel variables are
recognized by SPICE as meta-kernel keywords:
KERNELS_TO_LOAD
PATH_SYMBOLS
PATH_VALUES
Each kernel variable is discussed below.
KERNELS_TO_LOAD is a list of SPICE kernels to be
loaded into a program. If file
names do not fit within the kernel
pool 80 character limit, they may be
continued to subsequent array
elements by placing the continuation
character ('+') at the end of an
element and then placing the
remainder of the file name in the
next array element. (See the
examples below for an illustration
of this technique or consult the
routine STPOOL for further details.)
You may use one or more PATH_SYMBOL
assignments (see below) to specify
strings to be substituted for some
part of a file name.
PATH_SYMBOLS is a list of strings (without
embedded blanks) which if
encountered following the '$'
character will be replaced with the
corresponding PATH_VALUES string.
Note that PATH_SYMBOLS are
interpreted only in values
associated with the KERNELS_TO_LOAD
variable. There must be a one-to-one
correspondence between the values
supplied for PATH_SYMBOLS and
PATH_VALUES. For the purpose of
determining this correspondence, any
path value that is continued over
multiple array elements counts as a
single value.
PATH_VALUES is a list of expansions to use when
PATH_SYMBOLS are encountered. If
path values do not fit within the
kernel pool 80 character limit, they
may be continued in the same way as
file names (see the KERNELS_TO_LOAD
description above).
These kernel pool variables persist within the kernel
pool only until all kernels associated with the
variable KERNELS_TO_LOAD have been loaded. Once all
specified kernels have been loaded, the variables
KERNELS_TO_LOAD, PATH_SYMBOLS and PATH_VALUES are
removed from the kernel pool.
Detailed_Output
None. The routine loads various SPICE kernels for use by your
application.
Parameters
FILSIZ is the maximum file name length that can be accommodated
by the kernel pool.
MAXFIL is the number of entries that can be stored in KEEPER's
kernel database. In this version of the toolkit MAXFIL
is set to 5300. Each time a kernel is loaded via
FURNSH, a database entry is created for that kernel.
If a meta-kernel is loaded, a database entry is created
for the meta-kernel itself and for all files referenced
in the meta-kernel's KERNELS_TO_LOAD specification.
Unloading a kernel or meta-kernel deletes database
entries created when the file was loaded.
The parameter MAXFIL is an upper bound on number of
SPICE kernels that can be loaded at any time via the
KEEPER interface, but the number of kernels that can be
loaded may be smaller, since re-loading a loaded kernel
or meta-kernel results in creation of additional
database entries.
Kernels loaded into the KEEPER system are subject to
constraints imposed by lower-level subsystems. The
binary kernel systems (SPK, CK, binary PCK, and EK)
have their own limits on the maximum number of kernels
that may be loaded.
The total number of DAF-based files (this set includes
SPKs, CKs, and binary PCKs) and DAS-based files (this
set includes EKs and DSKs) that may be loaded at any
time may not exceed 5000. This limit applies whether
the files are loaded via FURNSH or lower-level loaders
such as SPKLEF or DAFOPR. File access performance
normally will degrade as the number of loaded kernels
increases.
Exceptions
1) If a problem is encountered while trying to load FILE, an
error is signaled by a routine in the call tree of this
routine.
2) If the input FILE is a meta-kernel and some file in the
KERNELS_TO_LOAD assignment cannot be found, or if an error
occurs while trying to load a file specified by this
assignment, the error is signaled by a routine in the call
tree of this routine, and this routine will return. Any files
loaded prior to encountering the failure, including those
referenced by the KERNELS_TO_LOAD assignment, will remain
loaded.
3) If an attempt to load a text kernel fails while the kernel is
being parsed, any kernel variable assignments made before
the failure occurred will be retained in the kernel pool.
4) If a PATH_SYMBOLS assignment is specified without a
corresponding PATH_VALUES assignment, the error
SPICE(NOPATHVALUE) is signaled.
5) If a meta-text kernel is supplied to FURNSH that contains
instructions specifying that another meta-text kernel be
loaded, the error SPICE(RECURSIVELOADING) is signaled.
6) If the input file name has non-blank length exceeding FILSIZ
characters, the error SPICE(FILENAMETOOLONG) is signaled.
7) If the input file is a meta-kernel and some file in the
KERNELS_TO_LOAD assignment has name length exceeding FILSIZ
characters, the error SPICE(FILENAMETOOLONG) is signaled.
8) If the input file is a meta-kernel and some value in the
PATH_VALUES assignment has length exceeding FILSIZ
characters, the error SPICE(PATHTOOLONG) is signaled.
9) If the input file is a meta-kernel and some file in the
KERNELS_TO_LOAD assignment has, after symbol substitution,
combined name and path length exceeding FILSIZ characters,
the error SPICE(FILENAMETOOLONG) is signaled.
10) If a kernel pool variable name length exceeds its maximum
allowed length (see Kernel Required Reading, kernel.req), an
error is signaled by a routine in the call tree of this
routine.
Files
The input FILE is examined and loaded into the appropriate SPICE
subsystem. If the file is a meta-kernel, any kernels specified
by the KERNELS_TO_LOAD keyword (and if present, the PATH_SYMBOLS
and PATH_VALUES keywords) are loaded as well.
Particulars
This routine provides a uniform interface to the SPICE kernel
loading systems. It allows you to easily assemble a list of
SPICE kernels required by your application and to modify that set
without modifying the source code of programs that make use of
these kernels.
Examples
The numerical results shown for these examples 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) Load the leapseconds kernel naif0007.tls and the planetary
ephemeris SPK file de405s.bsp.
CALL FURNSH ( 'naif0007.tls' )
CALL FURNSH ( 'de405s.bsp' )
2) This example illustrates how you could create a meta-kernel
file for a program that requires several text and binary
kernels.
First create a list of the kernels you need in a text file as
shown below.
KPL/MK
File name: furnsh_ex2.tm
Here are the SPICE kernels required for my application
program.
Note that kernels are loaded in the order listed. Thus
we need to list the highest priority kernel last.
\begindata
KERNELS_TO_LOAD = (
'/home/mydir/kernels/spk/lowest_priority.bsp',
'/home/mydir/kernels/spk/next_priority.bsp',
'/home/mydir/kernels/spk/highest_priority.bsp',
'/home/mydir/kernels/text/leapsecond.ker',
'/home/mydir/kernels+',
'/custom+',
'/kernel_data/constants.ker',
'/home/mydir/kernels/text/sclk.tsc',
'/home/mydir/kernels/ck/c-kernel.bc' )
\begintext
End of meta-kernel
Note that the file name
/home/mydir/kernels/custom/kernel_data/constants.ker
is continued across several lines in the right hand side of
the assignment of the kernel variable KERNELS_TO_LOAD.
Once you've created your list of kernels, call FURNSH near the
beginning of your application program to load the meta-kernel
automatically at program start up.
CALL FURNSH ( 'furnsh_ex2.tm' )
This will cause each of the kernels listed in your meta-kernel
to be loaded.
3) This example illustrates how you can simplify the previous
kernel list by using PATH_SYMBOLS.
KPL/MK
File name: furnsh_ex3.tm
Here are the SPICE kernels required for my application
program.
We are going to let A substitute for the directory that
contains SPK files; B substitute for the directory that
contains C-kernels; and C substitute for the directory that
contains text kernels. And we'll let D substitute for
a "custom" directory that contains a special planetary
constants kernel made just for our mission.
Note that our PATH_VALUES and the corresponding
PATH_SYMBOLS must be listed in the same order.
\begindata
PATH_VALUES = ( '/home/mydir/kernels/spk',
'/home/mydir/kernels/ck',
'/home/mydir/kernels/text',
'/home/mydir/kernels/custom/kernel_data' )
PATH_SYMBOLS = ( 'A',
'B',
'C',
'D' )
KERNELS_TO_LOAD = ( '$A/lowest_priority.bsp',
'$A/next_priority.bsp',
'$A/highest_priority.bsp',
'$C/leapsecond.ker',
'$D/constants.ker',
'$C/sclk.tsc',
'$B/c-kernel.bc' )
\begintext
End of meta-kernel
4) This example illustrates continuation of path values. The
meta-kernel shown here is a modified version of that from
example 3.
KPL/MK
File name: furnsh_ex4.tm
Here are the SPICE kernels required for my application
program.
We are going to let A substitute for the directory that
contains SPK files; B substitute for the directory that
contains C-kernels; and C substitute for the directory that
contains text kernels. And we'll let D substitute for
a "custom" directory that contains a special planetary
constants kernel made just for our mission.
Note that our PATH_VALUES and the corresponding
PATH_SYMBOLS must be listed in the same order.
The values for path symbols A and D are continued over
multiple lines.
\begindata
PATH_VALUES = ( '/very_long_top_level_path_name/mydir/+',
'kernels/spk',
'/home/mydir/kernels/ck',
'/home/mydir/kernels/text',
'/very_long_top_level_path_name+',
'/mydir/kernels/custom+',
'/kernel_data' )
PATH_SYMBOLS = ( 'A',
'B',
'C',
'D' )
KERNELS_TO_LOAD = ( '$A/lowest_priority.bsp',
'$A/next_priority.bsp',
'$A/highest_priority.bsp',
'$C/leapsecond.ker',
'$D/constants.ker',
'$C/sclk.tsc',
'$B/c-kernel.bc' )
\begintext
End of meta-kernel
5) Load a meta-kernel containing three kernels, and separately,
a text kernel and a binary PCK. Count the number of loaded
files before and after calling KCLEAR.
Use the meta-kernel shown below to load the required SPICE
kernels.
KPL/MK
File name: furnsh_ex5.tm
This meta-kernel is intended to support operation of SPICE
example programs. The kernels shown here should not be
assumed to contain adequate or correct versions of data
required by SPICE-based user applications.
In order for an application to use this meta-kernel, the
kernels referenced here must be present in the user's
current working directory.
The names and contents of the kernels referenced
by this meta-kernel are as follows:
File name Contents
--------- --------
de421.bsp Planetary ephemeris
pck00009.tpc Planet orientation and
radii
naif0012.tls Leapseconds
\begindata
KERNELS_TO_LOAD = ( 'de421.bsp',
'naif0012.tls',
'pck00009.tpc' )
\begintext
End of meta-kernel
Use the PCK kernel below as the binary PCK required for the
example.
earth_latest_high_prec.bpc
Use the FK kernel below as the text kernel required for the
example.
RSSD0002.TF
Example code begins here.
PROGRAM FURNSH_EX5
IMPLICIT NONE
C
C Local variables.
C
INTEGER COUNT
C
C Load several kernel files.
C
CALL FURNSH ( 'furnsh_ex5.tm' )
CALL FURNSH ( 'RSSD0002.TF' )
CALL FURNSH ( 'earth_latest_high_prec.bpc' )
C
C Count the number of loaded kernel files.
C
CALL KTOTAL ( 'ALL', COUNT )
WRITE(*,'(A,I2)') 'The total number of kernels after '
. // 'final FURNSH: ', COUNT
C
C Clear the KEEPER system, retrieve the number of loaded
C after the clear.
C
CALL KCLEAR()
CALL KTOTAL ( 'ALL', COUNT )
WRITE(*,'(A,I2)') 'The total number of kernels after '
. // 'KCLEAR : ', COUNT
END
When this program was executed on a Mac/Intel/gfortran/64-bit
platform, the output was:
The total number of kernels after final FURNSH: 6
The total number of kernels after KCLEAR : 0
Restrictions
1) A meta-kernel cannot reference another meta-kernel.
2) Failure during an attempt to load a text kernel or a
meta-kernel can result in a subset of the intended kernel
variables being set or a subset of the intended files
being loaded. FURNSH does not "clean up" so as to undo the
effects of a failed load operation.
3) When a kernel is specified with a relative path, this path
should be valid at the time when FURNSH is called and stay
valid for the rest of the application run. This is required
because SPICE stores kernel names as provided by the caller
and uses them to open and close binary kernels as needed
by the DAF/DAS handle manager subsystem (behind the scenes,
to allow reading many more binary kernels than available
logical units), and to automatically reload into the POOL
the rest of text kernels that should stay loaded when a
particular text kernel is unloaded.
Changing the working directory from within an application
during an application run after calling FURNSH to load
kernels specified using relative paths is likely to
invalidate stored paths and prevent open/close and unload
operations mentioned above. A simple workaround when this
is needed is to specify kernels using absolute paths.
Literature_References
None.
Author_and_Institution
C.H. Acton (JPL)
N.J. Bachman (JPL)
J. Diaz del Rio (ODC Space)
B.V. Semenov (JPL)
W.L. Taber (JPL)
E.D. Wright (JPL)
Version
SPICELIB Version 5.0.1, 08-AUG-2021 (JDR)
Edited the header to comply with NAIF standard.
Created complete code example from existing code fragments.
Added KERNEL to $Required_Reading section.
Added FILSIZ to the $Declarations section.
Added a restriction about specifying kernels using relative
paths to the $Restrictions section.
SPICELIB Version 5.0.0, 01-FEB-2017 (NJB) (BVS)
Updated to support use of DSKs.
Updated description of MAXFIL in the header.
Updated the $Author_and_Institution section.
SPICELIB Version 4.1.0, 01-JUL-2014 (NJB) (BVS)
Updated discussion of partially completed kernel loading.
Last update was 12-APR-2012 (BVS)
Changed to use SEPOOL instead of STPOOL to reduce loading time
for large meta-kernels due to n^2 delay in STPOOL.
SPICELIB Version 4.0.1, 10-FEB-2010 (EDW)
Added mention of the restriction on kernel pool variable
names to MAXLEN (defined in pool.f) characters or less.
SPICELIB Version 4.0.0, 02-APR-2009 (NJB)
Continued path values are now supported. FURNSH now rejects
file names longer than FILSIZ characters.
SPICELIB Version 2.0.3, 27-APR-2007 (NJB)
Fixed header typo: added quotes to literal string
input arguments in example FURNSH calls.
SPICELIB Version 2.0.2, 15-NOV-2006 (NJB)
Added description of parameter MAXFIL to header.
SPICELIB Version 2.0.1, 29-JUL-2003 (NJB) (CHA)
Numerous updates to improve clarity. Some corrections were
made.
SPICELIB Version 2.0.0, 23-AUG-2001 (WLT)
Added a call to CVPOOL in FURNSH so that watches that are
triggered are triggered by loading Meta-kernels and not by
some external interaction with the kernel pool.
SPICELIB Version 1.1.0, 19-SEP-2000 (WLT)
Corrected the error message template used
by ZZLDKER
SPICELIB Version 1.0.1, 16-DEC-1999 (NJB)
Documentation fix: corrected second code example in the
header of this entry point. The example previously used the
kernel variable PATH_NAMES; that name has been replaced with
the correct name PATH_VALUES.
SPICELIB Version 1.0.0, 01-JUL-1999 (WLT)
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Fri Dec 31 18:36:23 2021