160 lines
3.3 KiB
C
160 lines
3.3 KiB
C
/*
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lib/comedi.c
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comedi library routines
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COMEDI - Linux Control and Measurement Device Interface
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Copyright (C) 1997-8 David A. Schleef <ds@stm.lbl.gov>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <stdio.h>
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#include <math.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/ioctl.h>
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#include <errno.h>
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#include <comedi.h>
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#include <string.h>
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#include <libinternal.h>
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/* dt282x timer */
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static int dt282x_timer(double freq,unsigned int *trigvar,double *actual_freq)
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{
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int divider,prescaler;
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double basefreq=4e6;
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divider=floor(4e6/(freq));
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prescaler=0;
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while(divider>255){
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prescaler++;
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divider>>=1;
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basefreq/=2;
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}
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if(prescaler==1){
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prescaler++;
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divider>>=1;
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basefreq/=2;
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}
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if(prescaler>=16)return -1;
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*trigvar=(prescaler<<8)|(255-divider);
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*actual_freq=basefreq/divider;
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return 0;
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}
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/* dt2814 timer */
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static int dt2814_timer(double freq,unsigned int *trigvar,double *actual_freq)
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{
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double f;
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int i;
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f=1e5;
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for(i=0;i<8;i++){
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if(f-freq<freq-f/10){
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*trigvar=i;
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*actual_freq=f;
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return 0;
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}
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f/=10;
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}
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*trigvar=i;
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*actual_freq=f;
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return 0;
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}
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/* atmio/pcimio timer */
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static int atmio_timer(double freq,unsigned int *trigvar,double *actual_freq)
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{
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unsigned int divider;
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divider=floor(20e6/(freq));
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*actual_freq=20e6/divider;
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*trigvar=divider-1;
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return 0;
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}
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/* acl8112 timer */
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static int acl8112_timer(double freq,unsigned int *trigvar,double *actual_freq)
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{
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int divider,prescaler;
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double basefreq=2e6;
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/* XXX my notes say that the prescaler and divider cannot
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be 1. This needs to be checked. --ds */
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/* Force at least one division to get something in CTR2. */
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prescaler=1;
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divider = basefreq/(freq);
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while(divider>32767){
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prescaler*=2;
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divider>>=1;
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}
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*trigvar = (prescaler<<16) | divider;
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*actual_freq=basefreq/(divider*prescaler);
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return 0;
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}
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/* nanosec timer */
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static int nanosec_timer(double freq,unsigned int *trigvar,double *actual_freq)
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{
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*trigvar=(1e9/freq);
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*actual_freq=1e9/(*trigvar);
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return 0;
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}
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typedef int (*timerfunc)(double freq,unsigned int *trigvar,double *actual_freq);
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static timerfunc timer_functions[]={
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NULL,
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dt282x_timer,
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dt2814_timer,
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atmio_timer,
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acl8112_timer,
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nanosec_timer,
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};
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#define N_TIMERTYPES 6
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int comedi_get_timer(comedi_t *it,unsigned int subdev,double freq,
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unsigned int *trigvar,double *actual_freq)
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{
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int timer_type;
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if(!it || !trigvar || !actual_freq)
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return -1;
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timer_type=it->subdevices[subdev].timer_type;
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if(timer_type==0 || timer_type>=N_TIMERTYPES)
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return -1;
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return (timer_functions[timer_type])(freq,trigvar,actual_freq);
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}
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