Table of contents
CSPICE_DASOPS opens a scratch DAS file for writing.
The call:
[handle] = cspice_dasops
returns:
handle the file handle associated with the scratch file opened by
this routine.
[1,1] = size(handle); int32 = class(handle)
This handle is used to identify the file in subsequent
calls to other DAS routines.
SPICE_DAS_FTSIZE
is the maximum number of DAS files that a user can have open
simultaneously. This includes any files used by the DAS system
when closing files opened with write access. Currently,
cspice_dascls (via the SPICELIB routine DASSDR) opens a
scratch DAS file using cspice_dasops to segregate (sort by
data type) the records in the DAS file being closed.
Segregating the data by type improves the speed of access to
the data.
In order to avoid the possibility of overflowing the DAS file
table we recommend, when at least one DAS file is open with
write access, that users of this software limit themselves to
at most SPICE_DAS_FTSIZE - 2 other open DAS files. If no files
are to be open with write access, then users may open
SPICE_DAS_FTSIZE files with no possibility of overflowing the
DAS file table.
Any numerical results shown for this example may differ between
platforms as the results depend on the SPICE kernels used as input
and the machine specific arithmetic implementation.
1) Create a DAS scratch file containing 10 integers, 5 double
precision numbers, and 4 characters, then print the logical
address ranges in use.
Example code begins here.
function dasops_ex1()
%
% Use a scratch file, since there's no reason to keep
% the file.
%
[handle] = cspice_dasops;
for i=1:10
cspice_dasadi( handle, i );
end
for i=1:5
cspice_dasadd( handle, double(i) );
end
%
% Add character data to the file. DAS character data are
% treated as a character array, not as a string. The
% following call adds only the first 4 characters to the
% DAS file.
%
cspice_dasadc( handle, 4, 1, 4, uint8('SPUDWXY') );
%
% Now check the logical address ranges.
%
[lastc, lastd, lasti] = cspice_daslla( handle );
fprintf( 'Last character address in use: %d\n', lastc )
fprintf( 'Last d.p. address in use : %d\n', lastd )
fprintf( 'Last integer address in use : %d\n', lasti )
%
% Scratch files are automatically deleted when they are
% closed.
%
cspice_dascls( handle );
When this program was executed on a Mac/Intel/Octave6.x/64-bit
platform, the output was:
Last character address in use: 4
Last d.p. address in use : 5
Last integer address in use : 10
This routine is a utility used by the DAS system to provide
work space needed when creating new DAS files.
The DAS files created by this routine have initialized file
records. The file type for a DAS scratch file is 'SCR ', so the
file type 'SCR ' is not available for general use. As with new
permanent files, these files are opened for write access. DAS
files opened by cspice_dasops are automatically deleted when they are
closed.
1) If the specified file cannot be opened without exceeding the
maximum allowed number of open DAS files, the error
SPICE(DASFTFULL) is signaled by a routine in the call tree of
this routine. No file will be created.
2) If file cannot be opened properly, an error is signaled by a
routine in the call tree of this routine. No file will be
created.
3) If the initial records in the file cannot be written, the
error SPICE(DASWRITEFAIL) is signaled by a routine in the call
tree of this routine. No file will be created.
4) If no logical units are available, an error is signaled by a
routine in the call tree of this routine. No file will be
created.
See output argument `handle'.
See SPICE_DAS_FTSIZE in the -Parameters section for a description of a
potential problem with overflowing the DAS file table when at
least one DAS file is opened with write access.
None.
DAS.REQ
MICE.REQ
None.
J. Diaz del Rio (ODC Space)
-Mice Version 1.0.0, 30-JUN-2021 (JDR)
open a scratch DAS file
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