SPICE Kernel Pool Required Reading

Index Page SPICE Kernel Pool Required Reading
## Table of Contents
       SPICE Kernel Pool Required Reading
          Abstract
          Managing Kernels
             The Generic Kernel Loader furnsh_c
             Kernel Priority
             Path Symbols
             Keeping Track of Loaded Kernels
             Reloading Kernels
             Load Limits
             Finding Out What's Loaded
             Unloading Kernels
             Loading of Non-native Text and Binary Kernels
          SPICE File Identification Word
          Introduction of Text Kernels and Kernel Pool
          The SPICE Text Kernel File Format
             String Continuation
          Fetching Data from the Kernel Pool
             Informational Functions
             Changing Kernel Pool Contents
             Detecting Changes in the Kernel Pool
          SPICE Subsystems that Rely on SPICE Text Kernels
             PCK-related Functions
             Time Conversion Functions
             Frame Transformation Functions
             Instrument Description Functions
          Summary of Functions
Top # SPICE Kernel Pool Required Reading Last revised on 2009 APR 08 by B. V. Semenov. Top ## Abstract The CSPICE kernel subsystem serves to load and unload SPICE kernel files, retrieve loaded data, and directly insert data into the ``kernel pool''. Top ## Managing Kernels Top ### The Generic Kernel Loader furnsh_c For the SPICE system to use kernel files, the files must be made known to the system and opened at run time. This activity is called ``loading'' kernels. CSPICE provides a simple function interface for this purpose. The principal kernel loading function is called furnsh_c (pronounced ``furnish''). The kernel system also provides a small set of functions that enable an application to find the names and attributes of kernels that have been loaded via furnsh_c. Previous versions of CSPICE loaded kernels using functions specific to each kernel type: SPK, CK, PCK, IK, LSK, EK; the binary kernel systems also supported a kernel unload facility. CSPICE continues to provide the original kernel loaders and unloaders, but you should use furnsh_c to load SPICE kernels. NAIF recommends that when loading multiple kernels, rather than sequential calls to furnsh_c, use a ``metakernel.'' A metakernel is a SPICE text kernel that lists the names of the kernels to load. At run time, the application supplies the name of the metakernel as an input argument to furnsh_c. For example, instead of loading kernels using the code fragment:
       #include "SpiceUsr.h"
            .
            .
            .
       furnsh_c ( "leapseconds.ker"  );
       furnsh_c ( "mgs.tsc"          );
       furnsh_c ( "generic.bsp"      );
       furnsh_c ( "mgs.bc"           );
       furnsh_c ( "earth.bpc"        );
       furnsh_c ( "mgs.bes"          );
one now may write
       #include "SpiceUsr.h"
            .
            .
            .
       furnsh_c ( "kernels.txt" );
where the file kernels.txt is a SPICE text kernel containing the lines
       \begindata

       KERNELS_TO_LOAD = ( 'leapseconds.ker',
                           'mgs.tsc',
                           'generic.bsp',
                           'mgs.bc',
                           'earth.bpc',
                           'mgs.bes'           )

       \begintext
This technique has the advantage of enabling a user to change the set of kernels loaded by the application without modifying source code. It also possible to use furnsh_c to load kernels in the older CSPICE style: the names of kernels to load can be supplied as input arguments to furnsh_c. For example, instead of using the series of loader calls shown earlier, one now may write
       #include "SpiceUsr.h"
            .
            .
            .

       #define NKER  6

       char  * kernels[NKER] = {  "leapseconds.ker",
                                  "mgs.tsc",
                                  "generic.bsp",
                                  "mgs.bc",
                                  "earth.bpc",
                                  "mgs.bes"        };

       for ( int i = 0;  i < NKER;  i++ )
          {
          furnsh_c ( kernels[i] );
          }
Top ### Kernel Priority The older CSPICE loaders allow users to prioritize kernel files via load order: kernels loaded later have higher priority than kernels loaded earlier. furnsh_c follows the same convention. When kernels are listed in a metakernel, those appearing later in the list have higher priority. The old prioritization scheme also applies to kernels supplied directly as arguments to furnsh_c. Top ### Path Symbols Inside a metakernel, it is sometimes necessary to qualify file names with their pathnames. To reduce both typing and the need to continue file names over multiple lines, metakernels allow users to define symbols for paths. This is done using the kernel variables
       PATH_VALUES
       PATH_SYMBOLS
To create symbols for path names, one assigns an array of path names to the variable PATH_VALUES. Next, one assigns an array of corresponding symbol names to the variable PATH_SYMBOLS. The nth symbol in the second array represents the nth path name in the first. Finally, one prefixes with path symbols the kernel names specified in the KERNELS_TO_LOAD variable. Each symbol is prefixed with a dollar sign to indicate that it is in fact a symbol. Suppose in our example above that the MGS kernels reside in the path
       /flight_projects/mgs/SPICE_kernels
and the other kernels reside in the path
       /generic/SPICE_kernels
Then we can add paths to our metakernel as follows:
       \begindata

       PATH_VALUES  = ( '/flight_projects/mgs/SPICE_kernels',
                        '/generic/SPICE_kernels'              )

       PATH_SYMBOLS = ( 'MGS',
                        'GEN' )

       KERNELS_TO_LOAD = ( '$GEN/leapseconds.ker',
                           '$MGS/mgs.tsc',
                           '$GEN/generic.bsp',
                           '$MGS/mgs.bc',
                           '$GEN/earth.bpc',
                           '$MGS/mgs.bes'           )

       \begintext
It is not required that paths be abbreviated using path symbols; it's simply a convenience. Note the symbols defined here are not related to the symbols supported by a host shell or any other operating system interface. Top ### Keeping Track of Loaded Kernels furnsh_c maintains a record of the load operations it has performed during a program run. This record is implemented using data structures of fixed size, so there is a limit on the number of the maximum number of loaded kernels furnsh_c can accommodate. When a loaded kernel is loaded via furnsh_c, a new entry is created in the record of loaded kernels, whether or not the kernel is already loaded. All load or unload (see the discussion of unload_c below) operations affect the list of loaded files and therefore affect the results returned by the routines ktotal_c, kdata_c, and kinfo_c, all of which are discussed below under ``Finding Out What's Loaded.'' Top ### Reloading Kernels Reloading an already loaded kernel decreases the available space in furnsh_c's list of loaded files. furnsh_c's treatment of reloaded files is thus slightly different from that performed by the CSPICE low-level kernel loaders, which handle a reload operation by first unloading the kernel in question, then loading it. The recommended method of increasing the priority of a loaded binary kernel, or of a metakernel containing binary kernels, is to unload it using unload_c (see below), then reload it using furnsh_c. This technique helps reduce clutter in furnsh_c's kernel list. Top ### Load Limits furnsh_c can currently keep track of up to 1300 kernels. The list of loaded kernels may contain multiple entries for a given physical file, so the number of maximum number of distinct loaded files may be smaller if some files have been reloaded. Unloading kernels via unload_c frees room in the file list, so there is no limit on the total number of load or unload operations performed in a program run. The DAF/DAS handle manager system imposes its own lower limit on the number of DAF and DAS files that may be loaded simultaneously. This limit is currently set to a total of 1000 DAF and DAS files. Top ### Finding Out What's Loaded CSPICE-based applications may need to determine at run time which files have been loaded. Applications may need to find the DAF or DAS handles of loaded binary kernels so that the kernels may be searched. Some applications may need to unload kernels to make room for others, or change the priority of loaded kernels at run time. CSPICE provides kernel access routines to support these needs. For every loaded kernel, an application can find the name of kernel, the kernel type (text or one of SPK, CK, PCK, or EK), the kernel's DAF or DAS handle if applicable, and the name of the metakernel used to load the kernel, again if applicable. The function ktotal_c returns the count of loaded kernels of a given type. The function kdata_c returns information on the nth kernel of a given type. The two functions are normally used together. Following is an example of how an application could retrieve summary information on the currently loaded SPK files:
          #include <stdio.h>
          #include "SpiceUsr.h"

          #define  FILLEN   128
          #define  TYPLEN   32
          #define  SRCLEN   128

          SpiceInt        which;
          SpiceInt        handle;

          SpiceChar       file  [FILLEN];
          SpiceChar       filtyp[TYPLEN];
          SpiceChar       source[SRCLEN];

          SpiceBoolean    found;
               .
               .
               .

          ktotal_c ( "spk", &count );

          if ( count == 0 )
             {
             printf ( "No SPK files loaded at this time.\n" );
             }
          else
             {
             printf ( "The loaded SPK files are: \n\n" );
             }

          for ( which = 0;  which < count;  which++ )
             {
             kdata_c ( which,  "spk",    FILLEN,   TYPLEN, SRCLEN,
                       file,   filtyp,  &source, &handle,  &found );
             printf ( "%s\n",  file   );
             }
Above, the input argument "spk" is a kernel type specifier. The allowed set of values is
       SPK  --- All SPK files are counted in the total.
       CK   --- All CK files are counted in the total.
       PCK  --- All binary PCK files are counted in the
                total.
       EK   --- All EK files are counted in the total.
       TEXT --- All text kernels that are not meta-text
                kernels are included in the total.
       META --- All meta-text kernels are counted in the
                total.
       ALL  --- Every type of kernel is counted in the
                total.
In this example, `filtyp' is a string indicating the type of kernel. `handle' is the file handle if the file is a binary SPICE kernel. `source' is the name of the metakernel used to load the file, if applicable. `found' indicates whether a file having the specified type and index was found. CSPICE also contains the function kinfo_c which returns summary information about a file whose name is already known. kinfo_c is called as follows:
          kinfo_c ( file,   TYPLEN, SRCLEN,
                    filtyp, source, &handle, &found );
Top ### Unloading Kernels CSPICE-based applications may need to remove loaded kernels. Possible reasons for this are: `--` To make room to load other kernels. `--` To change the priority of loaded kernel data. `--` To change the set of kernel data visible to CSPICE. The function unload_c acts as an inverse to furnsh_c: passing a kernel to unload_c undoes the effect of the last load operation performed on that kernel via furnsh_c. For binary kernels that have been loaded just once, the meaning of this is simple: the kernel is closed, and CSPICE data structures referring to the file's contents are adjusted to reflect the absence of the file. Text kernels and metakernels may be unloaded as well. Unloading a metakernel involves unloading the files referenced by the metakernel. Text kernels are unloaded by clearing the kernel pool and then reloading the other text kernels not designated for removal. Note that unloading text kernels has the side effect of wiping out kernel variables that have been set via the kernel pool's function write access interface. It is important to consider whether this side effect is acceptable when writing code that may unload text kernels or metakernels. unload_c is called as follows:
          unload_c ( kernel );
Top ### Loading of Non-native Text and Binary Kernels The various platforms supported by CSPICE use different end-of-line (EOL) indicators in text files:
       Environment                  Native End-Of-Line
                                    Indicator
       ___________                  _____________________

       PC DOS/Windows                <CR><LF>
       Unix                          <LF>
       Linux                         <LF>
       Alpha  Digital Unix           <LF>
       Mac OS X                      <LF>
       Macintosh Classic (OS9)       <CR>
As of CSPICE N0059, the CSPICE text kernel loaders, furnsh_c and ldpool_c, can read and parse non-native text files. The FORTRAN SPICELIB does not include this capability. Please be aware the CSPICE text file reader, rdtext_c, does not possess the capability to read non-native text files. Starting with the N0052 release of the SPICE Toolkit (January, 2002) certain supported platforms are able to read DAF-based binary files (SPK, CK and binary PCK) that were written using a different, or non-native, binary representation. This access is read-only; any operations requiring writing to the file (adding information to the comment area, or appending additional ephemeris data, for example) require prior conversion of the file to the native binary file format. See the Convert User's Guide, convert.ug, for details. Top ## SPICE File Identification Word The first few bytes of a SPICE kernel are used for the SPICE file identification word. In binary and text kernels this word consists of two string IDs separated by the ``/'' character. The first ID, identifying the file architecture of the SPICE kernel file (``DAF'', ``DAS'', ``KPL'', etc), is always three characters long. The second ID identifying the file type of the SPICE kernel file (``SPK'', ``PCK'', ``IK'', ``SCLK'', etc), is two to four characters long. In transfer format files (see convert.ug for details) this word consists of a single string ID. In binary kernels the SPICE file identification word always occupies the first eight bytes. If the combined length of the file architecture ID, ``/'', and the file type ID is less than 8 characters, the word is padded on the right to eight characters using blanks (e.g. ``DAF/SPK '', ``DAS/EK '', etc). The correct file identification word is written to a binary file automatically when the file is created by calling the kernel type specific ``open new file'' routine -- spkopn_c for SPK files, ckopn_c for CK files, etc. If a binary file is created by calling the architecture specific ``open new file'' routine -- dafonw_c for DAF files, dasonw_c for DAS files, etc, -- it is the caller's responsibility to specify the correct kernel type in the corresponding input argument of these routines to make sure the correct SPICE file identification word is written to the file. In text kernels the SPICE file identification word occupies the first six to eight characters and is immediately followed by the end-of-line terminator character(s), resulting in the identification word appearing on a line by itself. If the combined length of the file architecture ID, ``/'', and the file type ID is less than 8 characters, the word can but does not have to be padded on the right to eight characters using blanks (e.g. ``KPL/SCLK'', ``KPL/IK'', etc). Since most text kernels are created manually using a text editor, it is the responsibility of the person who makes the file to put the correct SPICE file identification word by itself on the first line of the file. In transfer format files the SPICE file identification word occupies the first six characters of the file and is followed by the expanded name of the format (e.g. ``DAFETF NAIF DAF ENCODED TRANSFER FILE''). The correct file identification word is written to a transfer format file automatically when the file is created by the SPICE utility programs TOXFR or SPACIT (see toxfr.ug and spacit.ug for details). This table lists the SPICE file identification words used in modern SPICE kernel types:
       Binary Kernels:

          SPK           DAF/SPK
          CK            DAF/CK
          PCK           DAF/PCK
          EK            DAS/EK

       Text Kernels:

          FK            KPL/FK
          IK            KPL/IK
          LSK           KPL/LSK
          MK            KPL/MK
          PCK           KPL/PCK
          SCLK          KPL/SCLK

       Transfer format files:

          DAF           DAFETF
          DAS           DASETF
The Toolkit includes the getfat_c routine that can be used to retrieve the kernel file architecture and type encapsulated in the SPICE file identification word. Top ## Introduction of Text Kernels and Kernel Pool A variety of SPICE text kernels that are read into and accessed through the kernel pool. These include: `--` Text PCK kernels `--` Leapseconds kernels `--` SCLK kernels `--` I kernels `--` Frame kernels Do not confuse SPICE text kernels with text ``transfer'' versions of SPK, CK, PCK or DAF files produced by the utilities SPACIT or TOXFR. The text transfer files are not intended to be used with the kernel pool and do not conform to the SPICE text kernel format. The kernel pool system interface is composed of two parts: a text file format and kernel pool access software. The software includes functions that read files conforming to the format, routines that allow direct insertion of data into the pool via function calls, functions that fetch data from the kernel pool, functions that return information about the current state of the pool, and utilities that manipulate various aspects of the pool. The SPICE text kernel format has a ``name = value'' structure similar to the format used to assign values to variables in languages such as C and FORTRAN. Details of the format are described below. The kernel pool may be viewed abstractly as a repository of associative arrays which map names to lists of numeric or string values. The kernel pool allows CSPICE-based programs to read data from SPICE text kernel files while maintaining the ``name = value'' associations established in the files. Alternatively, associative arrays may be inserted into the kernel pool via the pool's programming interface. Once name-value associations have been stored in the kernel pool, you may access the stored data through kernel pool look-up functions. These look-up functions use the names as keys to find the associated values. The look-up and other access functions are described in detail below. Top ## The SPICE Text Kernel File Format As the name implies, SPICE text kernel files contain only ASCII text. An additional restriction on the contents of SPICE text kernel files is that they contain no non-printing characters, such as tabs or formfeeds. We illustrate this format by way of example using an excerpt from a SPICE text planetary constants kernel (PCK) file. The format description given below applies to all SPICE text kernels; the specific data names shown below apply only to text PCK files.
       Planets first. Each has quadratic expressions for the direction
       (RA, Dec) of the north pole and the rotation of the prime meridian.
       Planets with satellites (except Pluto) also have linear expressions
       for the auxiliary (phase) angles used in the nutation and libration
       expressions of their satellites.

       \begindata

       BODY399_POLE_RA        = (    0.      -0.64061614  -0.00008386  )
       BODY399_POLE_DEC       = (  +90.      -0.55675303  +0.00011851  )
       BODY399_PM             = (   10.21  +360.98562970  +0.          )
       BODY399_LONG_AXIS      = (    0.                                )

       BODY3_NUT_PREC_ANGLES  = (  125.045    -1935.53
                                   249.390    -3871.06
                                   196.694  -475263.
                                   176.630  +487269.65
                                   358.219   -36000.    )

       \begintext

       Each satellite has similar quadratic expressions for the pole and
       prime meridian. In addition, some satellites have nonzero nutation
       and libration amplitudes. (The number of amplitudes matches the
       number of auxiliary phase angles of the primary.)

       \begindata

       BODY301_POLE_RA      = (  270.000   -0.64061614  -0.00008386   )
       BODY301_POLE_DEC     = (  +66.534   -0.55675303  +0.00011851   )
       BODY301_PM           = (   38.314  +13.1763581    0.           )
       BODY301_LONG_AXIS    = (    0.                                 )

       BODY301_NUT_PREC_RA  = (  -3.878  -0.120  +0.070  -0.017   0.     )
       BODY301_NUT_PREC_DEC = (  +1.543  +0.024  -0.028  +0.007   0.     )
       BODY301_NUT_PREC_PM  = (  +3.558  +0.121  -0.064  +0.016  +0.025  )

       \begintext

       Finally, we include the radii of the satellites and planets.

       \begindata

       BODY399_RADII    = (     6378.140    6378.140     6356.755  )
       BODY301_RADII    = (     1738.       1738.        1738.     )

       \begintext
In this example are several comment blocks. All are introduce by the control word:
       \begintext
A comment block may contain any number of comment lines. Once a comment block has begun, no special characters are required to introduce subsequent lines of comments within that block. A comment block is terminated by the control word
       \begindata
This control word also serves to introduce a block of data that will be stored in the kernel pool. Each of these control words must appear on a line by itself. Each variable definition consists of three components: `1.` A variable name. `2.` An assignment directive. This must be ``='' (direct assignment) or ``+='' (incremental assignment). `3.` A scalar or vector value. A variable name can include any printable the character except: `1.` `` '' (space) `2.` ``.'' (period) `3.` ``('' (open parentheses) `4.` ``)'' (close parentheses) `5.` ``=" (equal sign) `6.` TAB character NAIF recommends you do not use a variable name with ``+' as the last character. Direct assignments supersede previous assignments, whereas incremental assignments are added to previous assignments. For example, the series of assignments
       BODY301_NUT_PREC_RA  = -3.878
       BODY301_NUT_PREC_RA += -0.120
       BODY301_NUT_PREC_RA += +0.070
       BODY301_NUT_PREC_RA += -0.017
       BODY301_NUT_PREC_RA += 0.
has the same effect as the single assignment
       BODY301_NUT_PREC_RA = (  -3.878  -0.120  +0.070  -0.017   0 )
Dates, e.g.,
       FOOBAR_CALIBRATION_DATES = ( @31-JAN-1987,
                                    @2/4/87,
                                    @March-7-1987-3:10:39.221 )
may be entered in a wide variety of formats. There are two restrictions regarding the format of dates. They may not contain embedded blanks, and they must begin with the character
       @
Internally, dates are converted to TDB seconds past J2000 as they are read. As a result, dates, are treated as numeric data in the pool. Strings may be supplied by quoting the string value.
       MISSION_UNITS = ( 'KILOMETERS',
                         'SECONDS',
                         'KILOMETERS/SECOND' )
If you need to include a quote in the string value, use the FORTRAN convention of "doubling" the quote.
       MESSAGE = ( 'You can''t always get what you want.' )
The maximum length of as string that can be assigned as the value of a scalar kernel variable, or as an element of an array-valued kernel variable, is 80 characters. The types of values assigned to a kernel pool variable must all be the same. If you attempt to make an assignment such as the one shown here:
       ERROR_EXAMPLE = ( 1, 2, 'THREE', 4, 'FIVE' )
The kernel pool reader will regard the assignment as erroneous and reject it and any subsequent kernel pool assignments that appear in the text kernel. Top ### String Continuation It is possible to treat specified, consecutive components of a string array as a single ``continued'' string. String continuation is indicated by placing a user-specified sequence of non-blank characters at the end (excluding trailing blanks) of each string value that is to be concatenated to its successor. For example, if the character sequence
       //
is used as a continuation mark, the assignment
       CONTINUED_STRINGS = ( 'This //  ',
                             'is //  ',
                             'just //',
                             'one long //',
                             'string.',
                             'Here''s a second //',
                             'continued //'
                             'string.'              )
allows the string array elements on the right hand side of the assignment to be treated as the two strings
       This is just one long string.
       Here's a second continued string.
The CSPICE function stpool_c provides the capability of retrieving continued strings from the kernel pool. See the discussion below under ``Fetching Data from the Kernel Pool'' or the header of stpool_c for further information. Top ## Fetching Data from the Kernel Pool The values of variables stored in the kernel pool may be retrieved using the functions: gcpool_c Used to fetch character data from the kernel pool. gdpool_c Used to fetch double precision data from the kernel pool. gipool_c Used to fetch integer data from the kernel pool. Note that internally, all numeric data are stored as double precision values. This interface is provided as a convenience so that users may retrieve integer data directly from the kernel pool without having worry about converting from double precision values to integers. stpool_c Used to fetch continued strings from the kernel pool. The calling sequences are shown below.
       \literal
       gcpool_c( name, first, room,   lenout,  nvalues, values, found );
       gdpool_c( name, first, room,   nvalues, values,  found );
       gipool_c( name, first, room,   nvalues, values,  found );
       stpool_c( name, nth,   contin, lenout,  string,  size,   found );
The meanings of the arguments are as follows: `name' is the name of the item to retrieve. `first' is the index of the first item to retrieve from the array of values associated with `name'. `room' is the number of values that may be stored in the output array `values'. `lenout' is the maximum allowed length of the output string, including the terminating null character. `nvalues' is the number of items stored in `values' `values' is the output array of values associated with `name'. The data type of `values' depends upon the routine: for gcpool_c, `values' is an array of strings; for gdpool_c, `values' is an array of double precision numbers, for gipool_c, `values' is an array of integers. `found' indicates whether or not the requested data are is available in the kernel pool. For the function stpool_c `nth' is the index of the continued string to fetch. `contin' is the continuation marker. This is a sequence of characters used to indicate that the next string array element is to be concatenated to the marked element. `string' is the string value whose index is given by `nth'. `size' is the number of characters in the returned string, excluding the terminating null character. See the headers of these functions for a more extensive discussion of their arguments and use. Top ### Informational Functions Four routines are provided for retrieving general information about the contents of the kernel pool. dtpool_c Returns information about the existence, dimension and type of kernel pool variables. expool_c Returns information on the existence of a kernel pool variable. gnpool_c Allows retrieval of names of kernel pool variables that match a string pattern. szpool_c Returns information about the size of various structures used in the implementation of the kernel pool. These routines are discussed at length in their respective headers. Top ### Changing Kernel Pool Contents The main way in which you change the contents of the kernel pool is by ``loading'' a SPICE text kernel with the function furnsh_c. However, the kernel pool also provides a several other routines that allow you to change the contents of the pool. clpool_c clears (initializes) the kernel pool, deleting all the variables in the pool. lmpool_c Similar in effect to loading a text kernel via furnsh_c, but the text kernel is stored in an array of strings instead of an external file. pcpool_c Allows the insertion of a character variable directly into the kernel pool without supplying a text kernel. pdpool_c Allows the insertion of a double precision variable directly into the kernel pool without supplying a text kernel. pipool_c Allows the insertion of an integer variable directly into the kernel pool without supplying a text kernel. dvpool_c allows deletion of a specific variable from the kernel pool. (clpool_c deletes all variables from the kernel pool.) The following code fragment shows how the data normally provided in a leapseconds kernel could be loaded via lmpool_c. See the headers of the other functions for specific details regarding their use.
       #include "SpiceUsr.h"
              .
              .
              .
       #define  LNSIZE      81
       #define  BUFSIZE     28

       static SpiceChar     text [BUFSIZE][LNSIZE] =
          {
          "DELTET/DELTA_T_A =   32.184",
          "DELTET/K         =    1.657D-3",
          "DELTET/EB        =    1.671D-2",
          "DELTET/M         = (  6.239996D0",
          "                      1.99096871D-7 )",
          "DELTET/DELTA_AT  = ( 10, @1972-JAN-1",
          "                     11, @1972-JUL-1",
          "                     12, @1973-JAN-1",
          "                     13, @1974-JAN-1",
          "                     14, @1975-JAN-1",
          "                     15, @1976-JAN-1",
          "                     16, @1977-JAN-1",
          "                     17, @1978-JAN-1",
          "                     18, @1979-JAN-1",
          "                     19, @1980-JAN-1",
          "                     20, @1981-JUL-1",
          "                     21, @1982-JUL-1",
          "                     22, @1983-JUL-1",
          "                     23, @1985-JUL-1",
          "                     24, @1988-JAN-1",
          "                     25, @1990-JAN-1",
          "                     26, @1991-JAN-1",
          "                     27, @1992-JUL-1",
          "                     28, @1993-JUL-1",
          "                     29, @1994-JUL-1",
          "                     30, @1996-JAN-1",
          "                     31, @1997-JUL-1",
          "                     32, @1999-JAN-1)"
          };

          /*
          Add the contents of the buffer to the kernel pool:
          */
          lmpool_c ( text, BUFSIZE );
Top ### Detecting Changes in the Kernel Pool Since loading SPICE text kernels tends to happen only at program initialization, a function that relies on data in the kernel pool may run more efficiently if it can store a local copy of the values needed and update these only when a change occurs in the kernel pool. Two functions are available that allow a quick test to see whether kernel pool variables have been updated. swpool_c Sets up a "watcher" on a variable so that various "agents" can be notified when a variable has been updated. cvpool_c Indicates whether or not an agent's variable has been updated since the last time an agent checked with the pool. See the headers of these functions for details and examples of their use. Top ## SPICE Subsystems that Rely on SPICE Text Kernels Top ### PCK-related Functions The PCK kernel is CSPICE's source of the planetary constants needed to define the size, shape, and orientation of planets and satellites. The PCK text file format and functions which access PCK data are described in the PCK Required Reading, pck.req. Top ### Time Conversion Functions Routines that retrieve leapseconds or SCLK data directly from the kernel pool are documented in the time.req and sclk.req Required reading files, respectively. Top ### Frame Transformation Functions See the FRAMES Required Reading, frames.req, for a discussion of frame definition kernels. Top ### Instrument Description Functions Instrument kernels specify an instrument's field-of-view, size, shape, and orientation. Internal instrument timing parameters and other data relating to SPICE computations might also be placed in an I-kernel. Once an I-kernel containing the required keywords defining the instrument's FOV is loaded, the getfov_c routine can used to retrieve the FOV parameters. Top ## Summary of Functions Each kernel pool function name consists of a mnemonic which translates into a short description of the function's purpose.
       clpool_c ( Clear the pool of kernel variables )
       cvpool_c ( Check variable in the pool for update )
       dtpool_c ( Data for a kernel pool variable )
       dvpool_c ( Delete a variable from the kernel pool )
       expool_c ( Confirm the existence of a pool kernel variable )
       furnsh_c ( Furnish a program with SPICE kernels )
       gcpool_c ( Get character data from the kernel pool )
       gdpool_c ( Get d.p. values from the kernel pool )
       getfov_c ( Get instrument FOV configuration )
       gipool_c ( Get integers from the kernel pool )
       gnpool_c ( Get names of kernel pool variables )
       kdata_c  ( Kernel Data )
       kinfo_c  ( Kernel Information )
       ktotal_c ( Kernel Totals )
       ldpool_c ( Load variables from a kernel file into the pool )
       lmpool_c ( Load variables from memory into the pool )
       pcpool_c ( Put character strings into the kernel pool )
       pdpool_c ( Put d.p.'s into the kernel pool )
       pipool_c ( Put integers into the kernel pool )
       stpool_c ( String from pool )
       swpool_c ( Set watch on a pool variable )
       szpool_c ( Get size limitations of the kernel pool)
       unload_c ( Unload a kernel )