dafgs_c |
Table of contents
Proceduredafgs_c ( DAF, get summary ) void dafgs_c ( SpiceDouble sum[] ) AbstractReturn (get) the summary for the current array in the current DAF. Required_ReadingDAF KeywordsFILES Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- sum O Summary for current array. Detailed_InputNone. Detailed_Outputsum is the summary for the current array (the array found by the latest call to daffna_c or daffpa_c). Summaries are also called "segment descriptors." ParametersNone. Exceptions1) If this routine is called when no search is in progress in the current DAF, the error SPICE(DAFNOSEARCH) is signaled by a routine in the call tree of this routine. 2) If the DAF for which the "current" array's summary is to be returned has actually been closed, an error is signaled by a routine in the call tree of this routine. 3) If no array is current in the current DAF, the error SPICE(NOCURRENTARRAY) is signaled by a routine in the call tree of this routine. There is no current array when a search is started by dafbfs_c or dafbbs_c, but no calls to daffna_c or daffpa_c have been made yet, or whenever daffna_c or daffpa_c return the value SPICEFALSE in the `found' argument. FilesNone. ParticularsThe DAF search routines are: dafbfs_c Begin forward search. daffna Find next array. dafbbs_c Begin backward search. daffpa_c Find previous array. dafgs_c Get summary. dafgn_c Get name. dafgh_c Get handle. dafcs_c Continue search. The main function of these entry points is to allow the contents of any DAF to be examined on an array-by-array basis. Conceptually, the arrays in a DAF form a doubly linked list, which can be searched in either of two directions: forward or backward. It is possible to search multiple DAFs simultaneously. dafbfs_c (begin forward search) and daffna are used to search the arrays in a DAF in forward order. In applications that search a single DAF at a time, the normal usage is dafbfs_c ( handle ); daffna_c ( &found ); while ( found ) { dafgs_c ( sum ); dafgn_c ( name ); . . daffna_c ( &found ); } dafbbs_c (begin backward search) and daffpa_c are used to search the arrays in a DAF in backward order. In applications that search a single DAF at a time, the normal usage is dafbbs_c ( handle ); daffpa_c ( &found ); while ( found ) { dafgs_c ( sum ); dafgn_c ( name ); . . daffpa_c ( &found ); } In applications that conduct multiple searches simultaneously, the above usage must be modified to specify the handle of the file to operate on, in any case where the file may not be the last one specified by dafbfs_c or dafbbs_c. The routine dafcs_c (DAF, continue search) is used for this purpose. Below, we give an example of an interleaved search of two files specified by the handles handl1 and handl2. The directions of searches in different DAFs are independent; here we conduct a forward search on one file and a backward search on the other. Throughout, we use dafcs to specify which file to operate on, before calling daffna_c, daffpa_c, dafgs_c, or dafgn_c. dafbfs_c ( handl1 ); dafbbs_c ( handl2 ); dafcs_c ( handl1 ); daffna_c ( &found1 ); dafcs_c ( handl2 ); daffpa_c ( &found2 ); while ( found1 || found2 ) { if ( found1 ) { dafcs_c ( handl1 ); dafgs_c ( sum ); dafgn_c ( name ); . . dafcs_c ( handl1 ); daffna_c ( &found1 ); } if ( found2 ) { dafcs_c ( handl2 ); dafgs_c ( sum ); dafgn_c ( name ); . . dafcs_c ( handl2 ); daffpa_c ( &found2 ); } } At any time, the latest array found (whether by daffna_c or daffpa_c) is regarded as the "current" array for the file in which the array was found. The last DAF in which a search was started, executed, or continued by any of dafbfs_c, dafbbs_c, daffna_c, daffpa_c or dafcs_c is regarded as the "current" DAF. The summary and name for the current array in the current DAF can be obtained separately, as shown above, by calls to dafgs_c (get summary) and dafgn_c (get name). The handle of the current DAF can also be obtained by calling dafgh_c (get handle). Once a search has been begun, it may be continued in either direction. That is, daffpa_c may be used to back up during a forward search, and daffna_c may be used to advance during a backward search. ExamplesThe 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) See -Particulars. 2) Create a simple program to output the double precision and integer values stored in an SPK's segments descriptors. This function opens a DAF for read, performs a forwards search for the DAF arrays, prints segments description for each array found, then closes the DAF. Use the SPK kernel below as input DAF file for the program. de421.bsp Example code begins here. /. Program dafgs_ex1 ./ #include <stdio.h> #include "SpiceUsr.h" int main() { /. Local constants ./ /. Define the summary parameters appropriate for an SPK file. ./ #define ND 2 #define NI 6 #define MAXSUM 125 SpiceInt ic [ NI ]; SpiceInt handle; SpiceDouble dc [ ND ]; SpiceDouble sum [ MAXSUM ]; SpiceChar * kernel = "de421.bsp"; SpiceBoolean found; /. Open a DAF for read. Return a handle referring to the file. ./ dafopr_c ( kernel, &handle ); /. Begin a forward search on the file. ./ dafbfs_c ( handle ); /. Search until a DAF array is found. ./ daffna_c ( &found ); /. Loop while the search finds subsequent DAF arrays. ./ while ( found ) { dafgs_c ( sum ); dafus_c ( sum, ND, NI, dc, ic ); printf( " Doubles: %f %f \n", dc[0], dc[1] ); printf( "Integers: %d %d %d %d %d %d\n\n", (int)ic[0], (int)ic[1], (int)ic[2], (int)ic[3], (int)ic[4], (int)ic[5] ); /. Check for another segment. ./ daffna_c ( &found ); } /. Safely close the DAF. ./ dafcls_c ( handle ); return ( 0 ); } When this program was executed on a Mac/Intel/cc/64-bit platform, the output was: Doubles: -3169195200.000000 1696852800.000000 Integers: 1 0 1 2 641 310404 Doubles: -3169195200.000000 1696852800.000000 Integers: 2 0 1 2 310405 423048 Doubles: -3169195200.000000 1696852800.000000 Integers: 3 0 1 2 423049 567372 Doubles: -3169195200.000000 1696852800.000000 Integers: 4 0 1 2 567373 628976 Doubles: -3169195200.000000 1696852800.000000 Integers: 5 0 1 2 628977 674740 Doubles: -3169195200.000000 1696852800.000000 Integers: 6 0 1 2 674741 715224 Doubles: -3169195200.000000 1696852800.000000 Integers: 7 0 1 2 715225 750428 Doubles: -3169195200.000000 1696852800.000000 Integers: 8 0 1 2 750429 785632 Doubles: -3169195200.000000 1696852800.000000 Integers: 9 0 1 2 785633 820836 Doubles: -3169195200.000000 1696852800.000000 Integers: 10 0 1 2 820837 944040 Doubles: -3169195200.000000 1696852800.000000 Integers: 301 3 1 2 944041 1521324 Doubles: -3169195200.000000 1696852800.000000 Integers: 399 3 1 2 1521325 2098608 Doubles: -3169195200.000000 1696852800.000000 Integers: 199 1 1 2 2098609 2098620 Doubles: -3169195200.000000 1696852800.000000 Integers: 299 2 1 2 2098621 2098632 Doubles: -3169195200.000000 1696852800.000000 Integers: 499 4 1 2 2098633 2098644 Note, the final entries in the integer array contains the segment start/end indexes. The output indicates the search proceeded from the start of the file (low value index) towards the end (high value index). RestrictionsNone. Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) W.L. Taber (JPL) I.M. Underwood (JPL) E.D. Wright (JPL) Version-CSPICE Version 1.0.3, 25-AUG-2021 (JDR) Edited the header to comply with NAIF standard. Fixed typo in -Exceptions entry #3: daffpa_c is used to find the previous array, not the non existing API dafbna_c. -CSPICE Version 1.0.2, 28-JUN-2016 (EDW) Edit to Example code, SpiceInts output as ints using explicit casting. -CSPICE Version 1.0.1, 10-OCT-2012 (EDW) Added a functional code example to the -Examples section. Removed the obsolete Reference citation to "NAIF Document 167.0." -CSPICE Version 1.0.0, 31-JUL-1999 (NJB) (WLT) (IMU) Index_Entriesget DAF summary |
Fri Dec 31 18:41:03 2021