comedilib/lib/sv.c

/*
    lib/sv.c
    functions for slowly varying inputs

    COMEDILIB - Linux Control and Measurement Device Interface Library
    Copyright (C) 1997-2001 David A. Schleef <ds@schleef.org>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation, version 2.1
    of the License.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
    USA.
*/

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <string.h>

#include "libinternal.h"



int sv_measure_l(comedi_sv_t *it,double *data);
int sv_measure_s(comedi_sv_t *it,double *data);

EXPORT_ALIAS_DEFAULT(_comedi_sv_init,comedi_sv_init,0.7.18);
int _comedi_sv_init(comedi_sv_t *it,comedi_t *dev,unsigned int subd,unsigned int chan)
{
	if(!valid_chan(dev,subd,chan))return -1;
	if(!it)return -1;

	memset(it,0,sizeof(*it));

	it->dev=dev;
	it->subdevice=subd;
	it->chan=chan;
	it->n=100;

	return comedi_sv_update(it);
}

EXPORT_ALIAS_DEFAULT(_comedi_sv_update,comedi_sv_update,0.7.18);
int _comedi_sv_update(comedi_sv_t *it)
{
	if(!it)return -1;
	if(!valid_chan(it->dev,it->subdevice,it->chan))return -1;

	it->maxdata=comedi_get_maxdata(it->dev,it->subdevice,it->chan);

	/* check current range policy */
	/* check n */

	return 0;
}

EXPORT_ALIAS_DEFAULT(_comedi_sv_measure,comedi_sv_measure,0.7.18);
int _comedi_sv_measure(comedi_sv_t *it,double *data)
{
	if(it->dev->subdevices[it->subdevice].subd_flags & SDF_LSAMPL){
		return sv_measure_l(it,data);
	}else{
		return sv_measure_s(it,data);
	}
}

int sv_measure_l(comedi_sv_t *it,double *data)
{
	comedi_trig t;
	int ret=0;
	lsampl_t *val;
	unsigned int chan;
	comedi_range *rng;
	double sum;
	int i;
	int n;

	val=malloc(sizeof(*val)*it->n);

	chan=CR_PACK(it->chan,it->range,it->aref);
	
	t.subdev=it->subdevice;
	t.mode=0;
	t.flags=TRIG_DITHER;
	t.n_chan=1;
	t.chanlist=&chan;
	t.trigsrc=0;
	t.trigvar=0;
	t.trigvar1=0;

	rng=comedi_get_range(it->dev,it->subdevice,it->chan,it->range);

	for(n=0;n<it->n;){
		t.data=(void *)(val+n);
		t.n=it->n-n;
		i = comedi_ioctl(it->dev->fd, COMEDI_TRIG, (unsigned long)&t);
		if(i<=0){
			ret=i;
			goto out;
		}
		n+=i;
	}

	sum=0;
	for(i=0;i<it->n;i++){
		sum+=comedi_to_phys(val[i],rng,it->maxdata);
	}
	*data=sum/it->n;

out:
	free(val);

	return ret;
}

/* yes, these functions are _almost_ exactly the same... */

int sv_measure_s(comedi_sv_t *it,double *data)
{
	comedi_trig t;
	int ret=0;
	sampl_t *val;
	unsigned int chan;
	comedi_range *rng;
	double sum;
	int i;
	int n;

	val=malloc(sizeof(*val)*it->n);

	chan=CR_PACK(it->chan,it->range,it->aref);
	
	t.subdev=it->subdevice;
	t.mode=0;
	t.flags=TRIG_DITHER;
	t.n_chan=1;
	t.chanlist=&chan;
	t.data=val;
	t.n=it->n;
	t.trigsrc=0;
	t.trigvar=0;
	t.trigvar1=0;

	rng=comedi_get_range(it->dev,it->subdevice,it->chan,it->range);

	for(n=0;n<it->n;){
		t.data=val+n;
		t.n=it->n-n;
		i = comedi_ioctl(it->dev->fd, COMEDI_TRIG, (unsigned long)&t);
		if(i<=0){
			ret=i;
			goto out;
		}
		n+=i;
	}

	sum=0;
	for(i=0;i<it->n;i++){
		sum+=comedi_to_phys(val[i],rng,it->maxdata);
	}
	*data=sum/it->n;

out:
	free(val);

	return ret;
}