| dafec_c |
|
Table of contents
Procedure
dafec_c ( DAF extract comments )
void dafec_c ( SpiceInt handle,
SpiceInt bufsiz,
SpiceInt buffln,
SpiceInt * n,
void * buffer,
SpiceBoolean * done )
AbstractExtract comments from the comment area of a binary DAF. Required_ReadingDAF KeywordsFILES UTILITY Brief_I/O
VARIABLE I/O DESCRIPTION
-------- --- --------------------------------------------------
handle I Handle of binary DAF opened with read access.
bufsiz I Maximum size, in lines, of buffer.
buffln I Length of strings in output buffer.
n O Number of extracted comment lines.
buffer O Buffer where extracted comment lines are placed.
done O Indicates whether all comments have been extracted.
Detailed_Input
handle is the file handle of a binary DAF which has been opened with
read access.
bufsiz is the maximum number of comments that may be placed into
buffer. This would typically be the declared array size for
the Fortran character string array passed into this
routine.
buffln is the allowed length of each string element of the output
buffer. This length must large enough to hold the longest
output string plus the null terminator. The SPICE system
imposes no limit on the length of comment lines, so `buffln'
normally should be set to a "generous" value that is unlikely
to be exceeded.
Detailed_Output
n is the number of comment lines extracted from the comment area
of the binary DAF associated with `handle'. `n' will be
less than or equal to `bufsiz' on output.
buffer is an array containing comment lines read from the DAF
associated with `handle'. `buffer' should be declared
SpiceChar buffer[bufsiz][buffln];
On output, the first `n' strings of `buffer' will contain
comment text, with one comment line per string.
done is a logical flag indicating whether or not all of the
comment lines from the comment area of the DAF have
been read. This variable has the value SPICETRUE after the
last comment line has been read. It will have the value
SPICEFALSE otherwise.
If there are no comments in the comment area, this
variable will have the value SPICETRUE.
ParametersNone. Exceptions
1) If the size of the output line buffer is is not positive, the
error SPICE(INVALIDARGUMENT) is signaled by a routine in the
call tree of this routine.
2) If a comment line in a DAF is longer than the length of a
character string array element of `buffer', the error
SPICE(COMMENTTOOLONG) is signaled by a routine in the call
tree of this routine.
3) If the end of the comments cannot be found, i.e., the end of
comments marker is missing on the last comment record, the
error SPICE(BADCOMMENTAREA) is signaled by a routine in the
call tree of this routine.
4) If the number of comment characters scanned exceeds the number
of comment characters computed, the error
SPICE(BADCOMMENTAREA) is signaled by a routine in the call
tree of this routine.
5) If the binary DAF attached to `handle' is not open for reading,
an error is signaled by a routine in the call tree of this
routine.
6) If the `buffer' output string pointer is null, the error
SPICE(NULLPOINTER) is signaled.
7) If the `buffer' output string has length less than two
characters, the error SPICE(STRINGTOOSHORT) is signaled, since
the output string is too short to contain one character of
output data plus a null terminator.
FilesSee argument `handle' in -Detailed_Input. ParticularsA binary DAF contains an area which is reserved for storing annotations or descriptive textual information describing the data contained in a file. This area is referred to as the ``comment area'' of the file. The comment area of a DAF is a line oriented medium for storing textual information. The comment area preserves any leading or embedded white space in the line(s) of text which are stored, so that the appearance of the of information will be unchanged when it is retrieved (extracted) at some other time. Trailing blanks, however, are NOT preserved, due to the way that character strings are represented in standard Fortran 77. This routine will read the comments from the comment area of a binary DAF, placing them into a line buffer. If the line buffer is not large enough to hold the entire comment area, the portion read will be returned to the caller, and the DONE flag will be set to SPICEFALSE. This allows the comment area to be read in ``chunks,'' a buffer at a time. After all of the comment lines have been read, the `done' flag will be set to SPICETRUE. This routine can be used to ``simultaneously'' extract comments from the comment areas of multiple binary DAFs. See Example 2 in the -Examples section. Examples
The numerical results shown for this example 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) The following example will extract the entire comment area of a
binary DAF, displaying the comments on the terminal screen.
Example code begins here.
/.
Program dafec_ex1
./
#include <stdio.h>
#include "SpiceUsr.h"
int main()
{
#define FILSIZ 256
#define LINLEN 1001
#define BUFFSZ 25
SpiceBoolean done = SPICEFALSE;
SpiceChar daf [FILSIZ];
SpiceChar buffer [BUFFSZ][LINLEN];
SpiceInt handle;
SpiceInt i;
SpiceInt n;
prompt_c ( "Enter name of DAF > ", FILSIZ, daf );
dafopr_c ( daf, &handle );
while ( !done )
{
dafec_c ( handle, BUFFSZ, LINLEN, &n, buffer, &done );
for ( i = 0; i < n; i++ )
{
printf ( "%s\n", buffer[i] );
}
}
return ( 0 );
}
When this program was executed on a Mac/Intel/cc/64-bit
platform, using the SPK file named earthstns_itrf93_201023.bsp as
input DAF file, the output was:
Enter name of DAF > earthstns_itrf93_201023.bsp
SPK for DSN Station Locations
=====================================================================
Original file name: earthstns_itrf93_201023.bsp
Creation date: 2020 October 28 12:30
Created by: Nat Bachman (NAIF/JPL)
Introduction
=====================================================================
This file provides geocentric states---locations and velocities---f***
set of DSN stations cited in the list below under "Position Data." ***
position vectors point from the earth's barycenter to the stations.***
velocities are estimates of the derivatives with respect to time of***
vectors; in this file, velocities are constant. Station velocities ***
magnitudes on the order of a few cm/year.
The states in this file are given relative to the terrestrial refer***
frame ITRF93.
This SPK file has a companion file
earthstns_fx_201023.bsp
which differs from this one only in that it uses the reference
frame alias 'EARTH_FIXED'. See the comment area of that file
and the Frames Required Reading for details.
Revision description
--------------------
This kernel contains data from a single, current source: [1].
This kernel supersedes the kernels
earthstns_itrf93_050714.bsp
dss_53_prelim_itrf93_201018.bsp (data in this kernel are identical)
dss_56_prelim_itrf93_201018.bsp (data in this kernel are improved)
dss_35_36_prelim_itrf93_140620.bsp (data in this kernel are impr***
The set of stations covered by this file has changed from that of t***
earthstns_itrf93_050714.bsp
as follows:
Deleted stations (not present in current file):
PARKES
DSS-12
DSS-16
DSS-17
DSS-23
DSS-27
DSS-28
DSS-33
DSS-42
DSS-46
DSS-49 (alternate name for PARKES)
DSS-61
DSS-64 (alternate name for DSS-65)
DSS-66
Other deleted data:
Position data for the old location of DSS-65 prior to 2005 Ju***
TDB are no longer included. This file extrapolates current data
backward in time for the entire time period covered by this f***
The superseded file
earthstns_itrf93_050714.bsp
should be used to obtain the old location of DSS-65 for dates***
to 2005 July 3 TDB.
Added stations:
DSS-35
DSS-36
DSS-56
Name transfers---name now refers to a new station:
DSS-53
Planned updates
---------------
Updates will be be made to keep this file in sync with updates to the
source document [1].
Values for DSS-53 are expected to be updated. Values for DSS-23 wil***
added. There is no schedule for these changes at this time.
[...]
Warning: incomplete output. Only 100 out of 532 lines have been
provided. 12 lines extended past the right margin of the header
and have been truncated. These lines are marked by "***" at the
end of each line.
Restrictions
1) The comment area may consist only of printing ASCII
characters, decimal values 32 - 126.
2) There is NO maximum length imposed on the significant portion
of a text line that may be placed into the comment area of a
DAF. The maximum length of a line stored in the comment area
should be kept reasonable, so that they may be easily
extracted. A good value for this would be 1000 characters, as
this can easily accommodate ``screen width'' lines as well as
long lines which may contain some other form of information.
3) This routine is only used to read records on environments
whose characters are a single byte in size. Updates
to this routine and routines in its call tree may be
required to properly handle other cases.
4) This routine is intended to be used on DAF files whose comment
area does not change while this routine is called to extract
comments, between the start and end of the extraction process.
If the comment area does change (gets updated, reduced,
extended, or deleted) between calls to this routine on the
same DAF file, the routine's outputs are undefined and
subsequent calls to it are likely to trigger an exception.
Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) K.R. Gehringer (JPL) Version
-CSPICE Version 1.1.0, 25-NOV-2021 (JDR)
Changed the input argument name "lenout" to "buffln" for
consistency with other routines.
Edited the header to comply with NAIF standard.
Added example's solution and modified input kernel.
-CSPICE Version 1.0.0, 16-NOV-2006 (NJB) (KRG)
Index_Entriesextract comments from a DAF |
Fri Dec 31 18:41:03 2021