| furnsh_c |
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Table of contents
Procedurefurnsh_c ( Furnish a program with SPICE kernels ) void furnsh_c ( ConstSpiceChar * file ) AbstractLoad one or more SPICE kernels into a program. Required_ReadingNone. KeywordsUTILITY Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- file I Name of SPICE kernel file (text or binary). Detailed_Input
file is the name of 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_c for further
details.)
Alternatively you may use a
PATH_SYMBOL (see below) to
substitute 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 the
KERNELS_TO_LOAD variable. There must
be a one-to-one correspondence
between the values supplied for
PATH_SYMBOLS and PATH_VALUES.
PATH_VALUES is a list of expansions to use when
PATH_SYMBOLS are encountered. See
the -Examples section for an
illustration of use of PATH_SYMBOLS
and PATH_VALUES.
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_OutputNone. 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. FILSIZ is currently set to 255.
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 by a routine in the call tree
of this routine.
5) If a meta-text kernel is supplied to furnsh_c that contains
instructions specifying that another meta-text kernel be
loaded, the error SPICE(RECURSIVELOADING) is signaled by a
routine in the call tree of this routine.
6) If the input file name has non-blank length exceeding FILSIZ
characters, the error SPICE(FILENAMETOOLONG) is signaled by a
routine in the call tree of this routine.
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 by a
routine in the call tree of this routine.
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 by a routine in the
call tree of this routine.
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 by a routine in the
call tree of this routine.
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.
11) If the `file' input string pointer is null, the error
SPICE(NULLPOINTER) is signaled.
12) If the `file' input string has zero length, the error
SPICE(EMPTYSTRING) is signaled.
FilesThe 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. In this version of the toolkit the maximum number of kernels that can loaded together is limited to 5300. Each time a kernel is loaded via furnsh_c, an internal kernel 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 value above is an upper bound on number of SPICE kernels that can be loaded at any time via the furnsh_c 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 via furnsh_c are subject to constraints imposed by lower-level subsystems. The binary kernel systems (SPK, CK, binary PCK, EK, and DSK) 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_c or lower-level loaders such as spklef_c or dafopr_c. File access performance normally will degrade slightly as the number of loaded kernels increases. ParticularsThis 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. Text kernels input to this routine need not have native line terminators for the platform. Lower level CSPICE routines can read and process non-native text files. This functionality does not exist in the Fortran SPICELIB. Only text kernel readers include the non-native read capability, (ldpool_c and furnsh_c), the generic text file line reader, rdtext_c requires native text files. Please refer to kernel.req for additional information. Kernel pool variable names are restricted to a length of 32 characters or less. 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.
furnsh_c ( "naif0007.tls" );
furnsh_c ( "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_c near the
beginning of your application program to load the meta-kernel
automatically at program start up.
furnsh_c ( "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_c.
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
./
#include <stdio.h>
#include "SpiceUsr.h"
int main( )
{
/.
Local variables.
./
SpiceInt count;
/.
Load several kernel files.
./
furnsh_c ( "furnsh_ex5.tm" );
furnsh_c ( "RSSD0002.TF" );
furnsh_c ( "earth_latest_high_prec.bpc" );
/.
Count the number of loaded kernel files.
./
ktotal_c ( "ALL", &count );
printf( "The total number of kernels after final furnsh_c: %1d\n",
count );
/.
Clear the KEEPER system, retrieve the number of loaded
after the clear.
./
kclear_c ();
ktotal_c ( "ALL", &count );
printf( "The total number of kernels after kclear_c : %1d\n",
count );
return ( 0 );
}
When this program was executed on a Mac/Intel/cc/64-bit
platform, the output was:
The total number of kernels after final furnsh_c: 6
The total number of kernels after kclear_c : 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_c 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_c 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_c 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_ReferencesNone. Author_and_InstitutionC.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
-CSPICE Version 1.3.5, 29-DEC-2021 (JDR)
Edited the header to comply with NAIF standard. Added extra
examples, including a complete code example.
Added entries #5 to #9 to -Exceptions section, and extended
entry #10.
Added FILSIZ description to -Parameters section.
Added a restriction about specifying kernels using relative
paths to the -Restrictions section.
-CSPICE Version 1.3.4, 01-FEB-2017 (BVS)
Updated discussion in the -Files section to mention the maximum
number of kernels that can be loaded together.
-CSPICE Version 1.3.3, 01-JUL-2014 (NJB)
Updated discussion of partially completed kernel loading.
-CSPICE Version 1.3.2, 10-FEB-2010 (EDW)
Corrected header section order. Added mention of the
restriction on kernel pool variable names to 32 characters
or less.
-CSPICE Version 1.0.4, 17-OCT-2005 (EDW)
Added text to -Particulars section informing of the
non-native kernel text file reading capability.
-CSPICE Version 1.0.3, 29-JUL-2003 (NJB) (CHA)
Numerous updates to improve clarity. Some corrections
were made.
-CSPICE Version 1.0.2, 03-JUL-2002 (NJB)
Documentation fix: corrected second code example. The example
previously used the kernel variable PATH_NAMES; that name has been
replaced with the correct name PATH_VALUES.
-CSPICE Version 1.0.1, 13-APR-2000 (NJB)
Replaced single quotes with double quotes in a code example.
-CSPICE Version 1.0.0, 01-SEP-1999 (NJB) (WLT)
Index_EntriesLoad SPICE data from a list of items |
Fri Dec 31 18:41:07 2021