QApplication and comedi_parse_calibration_file interaction

[Jan Benda]

Hi,

I am having a weired problem with comedi_parse_calibration_file. In a
simple test program that opens a comedi device, calls
comedi_parse_calibration_file() and then prints out some content of
the returned comedi_calibration_t structure, I get the values that are
stored in the calibration file (that was created by
comedi_soft_calibrate).

However, if I construct an QApplication object BEFORE I call
comedi_parse_calibration_file, the values in the comedi_calibration_t
structure are different and wrong. If QApplication is constructed
AFTER comedi_parse_calibration_file, everything is fine.

I am using comedilib from the git repository from today (but that bug
might exist since at least a year), and Qt Version 4.6.3 . It could be
that with older Qt versions this problem might not have occurred. The
simple call of the QApplication constructor should not interfere with
the following comedi_parse_calibration_file!

Any ideas how this could happen and how to solve this problem? Is this
a comedilib, Qt4, yacc/bison or flex problem?

Jan


Here are the details:

***** ai_calibration.cc *******
#include <cstdlib>
#include <iostream>
#include <comedilib.h>
#include <QApplication>

using namespace std;


int main(int argc, char *argv[])
{
comedi_t *dev;
char *calibpath;
comedi_calibration_t *calibration;

char filename[] = "/dev/comedi0";

dev = comedi_open( filename );
if ( dev == NULL ) {
fprintf(stderr, "error opening %s\n", filename);
return -1;
}


QApplication app( argc, argv );


// get calibration:
calibpath = comedi_get_default_calibration_path( dev );
calibration = comedi_parse_calibration_file( calibpath );



// print out:
cerr << "read calibration from file '" << calibpath << '\n';
cerr << " driver: " << calibration->driver_name << '\n';
cerr << " board: " << calibration->board_name << '\n';
cerr << " num: " << calibration->num_settings << '\n';
cerr << " settings[0].subdevice: " << calibration-
>settings[0].subdevice << '\n';
cerr << " settings[0].num_channels: " << calibration-
>settings[0].num_channels << '\n';
cerr << " settings[0].num_ranges: " << calibration-
>settings[0].num_ranges << '\n';
cerr << " settings[0].softcal[0].origin: " << calibration-
>settings[0].soft_calibration.to_phys[0].expansion_origin << '\n';
cerr << " settings[0].softcal[0].c0: " << calibration-
>settings[0].soft_calibration.to_phys[0].coefficients[0] << '\n';
cerr << " settings[0].softcal[0].c1: " << calibration-
>settings[0].soft_calibration.to_phys[0].coefficients[1] << '\n';


free( calibpath );

// cleanup calibration:
if ( calibration != 0 )
comedi_cleanup_calibration( calibration );
calibration = 0;

comedi_close( dev );

return 0;
}
*********

Compiled with

g++ -o ai_calibration ai_calibration.cc -I/usr/include/qt4 -I/usr/
include/qt4/QtGui -I/usr/include/qt4/QtCore -DQT_SHARED -l QtGui -l
QtCore -lcomedi -lm

on a Mint system (debian based).


Out put of the above program:

driver: ni_pcimio
board: pci-6259
num: 15
settings[0].subdevice: 0
settings[0].num_channels: 0
settings[0].num_ranges: 1
settings[0].softcal[0].origin: 3
settings[0].softcal[0].c0: 1
settings[0].softcal[0].c1: 3


If I construct QApplication after comedi_parse_calibration_file:

******
....
// get calibration:
calibpath = comedi_get_default_calibration_path( dev );
calibration = comedi_parse_calibration_file( calibpath );

QApplication app( argc, argv );

// print out:
...
******

I get the right output:

driver: ni_pcimio
board: pci-6259
num: 15
settings[0].subdevice: 0
settings[0].num_channels: 0
settings[0].num_ranges: 1
settings[0].softcal[0].origin: 32767
settings[0].softcal[0].c0: 0.00197151
settings[0].softcal[0].c1: 0.000322424


This is head -n 25 /usr/var/lib/comedi/calibrations/
ni_pcimio_pci-6259_comedi0:

#calibration file generated by comedi_calibrate
#Mon Jan 30 15:21:41 2012

{
driver_name => "ni_pcimio",
board_name => "pci-6259",
calibrations =>
[
{
subdevice => 0,
channels => [],
ranges => [0,],
arefs => [],
caldacs =>
[
],
softcal_to_phys =>
{
expansion_origin =>
3.27670000000000000000e+04,
coefficients =>
[1.97151128925224759791e-03,3.22423522400599625246e-04,-3.90347284338783529878e-13,-1.93886049898568612182e-17,],
},
},
{
subdevice => 0,
channels => [],