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* Force Feedback: Constant Force Stress Test
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* Copyright (C) 2001 Oliver Hamann
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#include <linux/input.h>
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#include <sys/ioctl.h>
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/* Helper for testing large bit masks */
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#define TEST_BIT(bit,bits) (((bits[bit>>5]>>(bit&0x1f))&1)!=0)
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/* Default values for the options */
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#define DEFAULT_DEVICE_NAME "/dev/input/event0"
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#define DEFAULT_UPDATE_RATE 25.0
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#define DEFAULT_MOTION_FREQUENCY 0.1
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#define DEFAULT_MOTION_AMPLITUDE 1.0
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#define DEFAULT_SPRING_STRENGTH 1.0
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const char * device_name = DEFAULT_DEVICE_NAME;
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double update_rate = DEFAULT_UPDATE_RATE;
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double motion_frequency = DEFAULT_MOTION_FREQUENCY;
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double motion_amplitude = DEFAULT_MOTION_AMPLITUDE;
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double spring_strength = DEFAULT_SPRING_STRENGTH;
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int stop_and_play = 0; /* Stop-upload-play effects instead of updating */
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/* Global variables about the initialized device */
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int axis_code, axis_min, axis_max;
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struct ff_effect effect;
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/* Parse command line arguments */
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void parse_args(int argc, char * argv[])
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if (argc<2) goto l_help;
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for (i=1; i<argc; i++) {
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if (!strcmp(argv[i],"-d") && i<argc-1) device_name =argv[++i];
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else if (!strcmp(argv[i],"-u") && i<argc-1) update_rate =atof(argv[++i]);
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else if (!strcmp(argv[i],"-f") && i<argc-1) motion_frequency=atof(argv[++i]);
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else if (!strcmp(argv[i],"-a") && i<argc-1) motion_amplitude=atof(argv[++i]);
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else if (!strcmp(argv[i],"-s") && i<argc-1) spring_strength =atof(argv[++i]);
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else if (!strcmp(argv[i],"-o")) ;
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printf("-------- ffcfstress - Force Feedback: Constant Force Stress Test --------\n");
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printf("Description:\n");
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printf(" This program is for stress testing constant non-enveloped forces on\n");
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printf(" a force feedback device via the event interface. It simulates a\n");
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printf(" moving spring force by a frequently updated constant force effect.\n");
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printf(" BE CAREFUL IN USAGE, YOUR DEVICE MAY GET DAMAGED BY THE STRESS TEST!\n");
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printf(" %s <option> [<option>...]\n",argv[0]);
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printf(" -d <string> device name (default: %s)\n",DEFAULT_DEVICE_NAME);
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printf(" -u <double> update rate in Hz (default: %.2f)\n",DEFAULT_UPDATE_RATE);
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printf(" -f <double> spring center motion frequency in Hz (default: %.2f)\n",DEFAULT_MOTION_FREQUENCY);
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printf(" -a <double> spring center motion amplitude 0.0..1.0 (default: %.2f)\n",DEFAULT_MOTION_AMPLITUDE);
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printf(" -s <double> spring strength factor (default: %.2f)\n",DEFAULT_SPRING_STRENGTH);
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printf(" -o dummy option (useful because at least one option is needed)\n");
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/* Initialize device, create constant force effect */
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unsigned long key_bits[32],abs_bits[32],ff_bits[32];
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struct input_event event;
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/* Open event device with write permission */
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device_handle = open(device_name,O_RDWR|O_NONBLOCK);
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if (device_handle<0) {
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fprintf(stderr,"ERROR: can not open %s (%s) [%s:%d]\n",
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device_name,strerror(errno),__FILE__,__LINE__);
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/* Which buttons has the device? */
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memset(key_bits,0,32*sizeof(unsigned long));
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if (ioctl(device_handle,EVIOCGBIT(EV_KEY,32*sizeof(unsigned long)),key_bits)<0) {
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fprintf(stderr,"ERROR: can not get key bits (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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/* Which axes has the device? */
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memset(abs_bits,0,32*sizeof(unsigned long));
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if (ioctl(device_handle,EVIOCGBIT(EV_ABS,32*sizeof(unsigned long)),abs_bits)<0) {
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fprintf(stderr,"ERROR: can not get abs bits (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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/* Now get some information about force feedback */
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memset(ff_bits,0,32*sizeof(unsigned long));
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if (ioctl(device_handle,EVIOCGBIT(EV_FF ,32*sizeof(unsigned long)),ff_bits)<0) {
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fprintf(stderr,"ERROR: can not get ff bits (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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/* Which axis is the x-axis? */
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if (TEST_BIT(ABS_X ,abs_bits)) axis_code=ABS_X;
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else if (TEST_BIT(ABS_RX ,abs_bits)) axis_code=ABS_RX;
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else if (TEST_BIT(ABS_WHEEL,abs_bits)) axis_code=ABS_WHEEL;
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fprintf(stderr,"ERROR: no suitable x-axis found [%s:%d]\n",
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/* get axis value range */
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if (ioctl(device_handle,EVIOCGABS(axis_code),valbuf)<0) {
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fprintf(stderr,"ERROR: can not get axis value range (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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if (axis_min>=axis_max) {
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fprintf(stderr,"ERROR: bad axis value range (%d,%d) [%s:%d]\n",
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axis_min,axis_max,__FILE__,__LINE__);
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/* force feedback supported? */
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if (!TEST_BIT(FF_CONSTANT,ff_bits)) {
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fprintf(stderr,"ERROR: device (or driver) has no force feedback support [%s:%d]\n",
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/* Switch off auto centering */
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memset(&event,0,sizeof(event));
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event.code=FF_AUTOCENTER;
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if (write(device_handle,&event,sizeof(event))!=sizeof(event)) {
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fprintf(stderr,"ERROR: failed to disable auto centering (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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/* Initialize constant force effect */
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memset(&effect,0,sizeof(effect));
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effect.type=FF_CONSTANT;
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effect.trigger.button=0;
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effect.trigger.interval=0;
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effect.replay.length=0xffff;
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effect.replay.delay=0;
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effect.u.constant.level=0;
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effect.direction=0xC000;
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effect.u.constant.envelope.attack_length=0;
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effect.u.constant.envelope.attack_level=0;
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effect.u.constant.envelope.fade_length=0;
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effect.u.constant.envelope.fade_level=0;
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if (ioctl(device_handle,EVIOCSFF,&effect)==-1) {
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fprintf(stderr,"ERROR: uploading effect failed (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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memset(&event,0,sizeof(event));
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event.code=effect.id;
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if (write(device_handle,&event,sizeof(event))!=sizeof(event)) {
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fprintf(stderr,"ERROR: starting effect failed (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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/* update the device: set force and query joystick position */
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void update_device(double force, double * position)
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struct input_event event;
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if (stop_and_play && effect.id!=-1) {
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if (ioctl(device_handle,EVIOCRMFF,effect.id)==-1) {
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fprintf(stderr,"ERROR: removing effect failed (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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if (force>1.0) force=1.0;
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if (force<-1.0) force=1.0;
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effect.u.constant.level=(short)(force*32767.0); /* only to be safe */
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effect.direction=0xC000;
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effect.u.constant.envelope.attack_level=(short)(force*32767.0); /* this one counts! */
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effect.u.constant.envelope.fade_level=(short)(force*32767.0); /* only to be safe */
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if (ioctl(device_handle,EVIOCSFF,&effect)==-1) {
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perror("upload effect");
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/* We do not exit here. Indeed, too frequent updates may be
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* refused, but that is not a fatal error */
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if (stop_and_play && effect.id!=-1) {
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memset(&event,0,sizeof(event));
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event.code=effect.id;
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if (write(device_handle,&event,sizeof(event))!=sizeof(event)) {
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fprintf(stderr,"ERROR: re-starting effect failed (%s) [%s:%d]\n",
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strerror(errno),__FILE__,__LINE__);
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while (read(device_handle,&event,sizeof(event))==sizeof(event)) {
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if (event.type==EV_ABS && event.code==axis_code) {
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*position=((double)(((short)event.value)-axis_min))*2.0/(axis_max-axis_min)-1.0;
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if (*position>1.0) *position=1.0;
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else if (*position<-1.0) *position=-1.0;
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/* little helper to print a graph bar from a value */
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void fprint_bar(FILE * file, double value, int radius)
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for (i=0; i<radius*2+1; i++) {
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if (i==radius) c='|';
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else if ((i<radius && value*radius<i-radius+0.25) ||
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(i>radius && value*radius>i-radius-0.25)) c='*';
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else if ((i<radius && value*radius<i-radius+0.75) ||
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(i>radius && value*radius>i-radius-0.75)) c='+';
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else if (i==0) c='<';
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else if (i==radius*2) c='>';
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/* main: perform the spring simulation */
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int main(int argc, char * argv[])
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double time,position,center,force;
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/* Parse command line arguments */
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parse_args(argc,argv);
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/* Initialize device, create constant force effect */
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printf("\n position center force\n");
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for (position=0, time=0;; time+=1.0/update_rate) {
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/* Spring center oscillates */
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center = sin( time * 2 * M_PI * motion_frequency ) * motion_amplitude;
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/* Calculate spring force */
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force = ( center - position ) * spring_strength;
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if (force > 1.0) force = 1.0;
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if (force < -1.0) force = -1.0;
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/* Print graph bars */
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fprint_bar(stdout,position,12);
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fprint_bar(stdout,center,12);
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fprint_bar(stdout,force,12);
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/* Set force and ask for joystick position */
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update_device(force,&position);
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usleep((unsigned long)(1000000.0/update_rate));
added
removed
.pc/ioctl-error-handling.patch/utils/ffcfstress.c
