From: Frank Mori Hess <fmhess@speakeasy.net>
Date: Wed, 3 Jan 2007 21:14:53 +0000 (+0000)
Subject: Made parse_options() write options to a struct instead of passing
X-Git-Tag: v0_8_0~43
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=fbdf65b4f517ad0b93a15204417147a0a9202ebd;p=comedilib.git

Made parse_options() write options to a struct instead of passing
them through global variables.
---

diff --git a/demo/antialias.c b/demo/antialias.c
index 1f1fb1e..08c6ec4 100644
--- a/demo/antialias.c
+++ b/demo/antialias.c
@@ -47,28 +47,30 @@ int main(int argc, char *argv[])
 {
 	lsampl_t data;
 	int ret;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
+		comedi_perror(options.filename);
 		exit(0);
 	}
 
-	data = value; 
-	if(verbose){
+	data = options.value;
+	if(options.verbose){
 		printf("writing %d to device=%s subdevice=%d channel=%d range=%d analog reference=%d\n",
-			data,filename,subdevice,channel,range,aref);
+			data, options.filename, options.subdevice, options.channel, options.range, options.aref);
 	}
 
-	ret=comedi_data_write(device,subdevice,channel,range,aref,data);
+	ret = comedi_data_write(device, options.subdevice, options.channel, options.range, options.aref, data);
 	if(ret<0){
-		comedi_perror(filename);
+		comedi_perror(options.filename);
 		exit(0);
 	}
 
-	printf("%d\n",data);
+	printf("%d\n", data);
 
 	ao_antialias((1000<<16)+1000);
 
diff --git a/demo/ao_mmap.c b/demo/ao_mmap.c
index 5da1464..50ea279 100644
--- a/demo/ao_mmap.c
+++ b/demo/ao_mmap.c
@@ -56,7 +56,7 @@ static int comedi_internal_trigger(comedi_t *dev, unsigned int subd, unsigned in
 static void write_waveform(sampl_t *buffer, int size, double amplitude, double offset, int maxdata)
 {
 	int i;
-	
+
 	for(i = 0; i < size; ++i)
 	{
 		double temp = (amplitude / 2.) * sin((2. * M_PI * i) / size) + offset;
@@ -82,47 +82,49 @@ int main(int argc, char *argv[])
 	double amplitude;
 	/* offset, in DAC units */
 	double offset;
-	int subdevice;
+	struct parsed_options options;
 
-	
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	options.subdevice = -1;
+	parse_options(&options, argc, argv);
 
 	/* Force n_chan to be 1 */
-	n_chan = 1;
+	options.n_chan = 1;
 
-	dev = comedi_open(filename);
+	dev = comedi_open(options.filename);
 	if(dev == NULL){
-		fprintf(stderr, "error opening %s\n", filename);
+		fprintf(stderr, "error opening %s\n", options.filename);
 		return -1;
 	}
-	subdevice = comedi_find_subdevice_by_type(dev,COMEDI_SUBD_AO,0);
+	if(options.subdevice < 0)
+		options.subdevice = comedi_find_subdevice_by_type(dev,COMEDI_SUBD_AO, 0);
 
-	maxdata = comedi_get_maxdata(dev,subdevice,0);
-	rng = comedi_get_range(dev,subdevice,0,0);
+	maxdata = comedi_get_maxdata(dev, options.subdevice, 0);
+	rng = comedi_get_range(dev, options.subdevice, 0, 0);
 
 	offset = (double)comedi_from_phys(0.0, rng, maxdata);
 	amplitude = (double)comedi_from_phys(1.0, rng, maxdata) - offset;
 
 	memset(&cmd,0,sizeof(cmd));
-	cmd.subdev = subdevice;
+	cmd.subdev = options.subdevice;
 	cmd.flags = 0;
 	cmd.start_src = TRIG_INT;
 	cmd.start_arg = 0;
 	cmd.scan_begin_src = TRIG_TIMER;
-	cmd.scan_begin_arg = 1e9/freq;
+	cmd.scan_begin_arg = 1e9 / options.freq;
 	cmd.convert_src = TRIG_NOW;
 	cmd.convert_arg = 0;
 	cmd.scan_end_src = TRIG_COUNT;
-	cmd.scan_end_arg = n_chan;
+	cmd.scan_end_arg = options.n_chan;
 	cmd.stop_src = TRIG_NONE;
 	cmd.stop_arg = 0;
 
 	cmd.chanlist = chanlist;
-	cmd.chanlist_len = n_chan;
+	cmd.chanlist_len = options.n_chan;
 
-	chanlist[0] = CR_PACK(channel,range,aref);
+	chanlist[0] = CR_PACK(options.channel, options.range, options.aref);
 
-	dump_cmd(stdout,&cmd);
+	dump_cmd(stdout, &cmd);
 
 	err = comedi_command_test(dev, &cmd);
 	if (err < 0) {
@@ -140,8 +142,8 @@ int main(int argc, char *argv[])
 		comedi_perror("comedi_command");
 		exit(1);
 	}
-	
-	size = comedi_get_buffer_size(dev, subdevice);
+
+	size = comedi_get_buffer_size(dev, options.subdevice);
 	fprintf(stderr, "buffer size is %d\n", size);
 	map = mmap(NULL, size, PROT_WRITE, MAP_SHARED, comedi_fileno(dev), 0);
 	if(map == MAP_FAILED)
@@ -157,20 +159,20 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 	printf("marking %i samples as written\n", num_samples);
-	ret = comedi_mark_buffer_written(dev, subdevice, size);
+	ret = comedi_mark_buffer_written(dev, options.subdevice, size);
 	if(ret < 0)
 	{
 		comedi_perror("comedi_mark_buffer_written");
 		exit(1);
 	}
-	ret = comedi_internal_trigger(dev, subdevice, 0);
+	ret = comedi_internal_trigger(dev, options.subdevice, 0);
 	if(ret<0){
 		comedi_perror("comedi_internal_trigger");
 		exit(1);
 	}
 	while(1)
 	{
-		int bytes_marked = comedi_get_buffer_contents(dev,subdevice);
+		int bytes_marked = comedi_get_buffer_contents(dev, options.subdevice);
 		int bytes_unmarked = size - bytes_marked;
 		if(bytes_marked < 0)
 		{
@@ -180,7 +182,7 @@ int main(int argc, char *argv[])
 		if(bytes_unmarked > 0)
 		{
 			// this keeps comedi from reporting a buffer underrun
-			if(comedi_mark_buffer_written(dev, subdevice, bytes_unmarked) < 0)
+			if(comedi_mark_buffer_written(dev, options.subdevice, bytes_unmarked) < 0)
 			{
 				comedi_perror("comedi_mark_buffer_written");
 				exit(1);
diff --git a/demo/ao_waveform.c b/demo/ao_waveform.c
index 0e9f6bc..2c24895 100644
--- a/demo/ao_waveform.c
+++ b/demo/ao_waveform.c
@@ -70,13 +70,12 @@ double offset			= 2048;
    inefficient */
 #define BUF_LEN 0x8000
 
-int subdevice;
 int external_trigger_number = 0;
 
 sampl_t data[BUF_LEN];
 
 void dds_output(sampl_t *buf,int n);
-void dds_init(void);
+void dds_init(double waveform_frequency, double update_frequency);
 
 /* This define determines which waveform to use. */
 #define dds_init_function dds_init_sine
@@ -113,50 +112,54 @@ int main(int argc, char *argv[])
 	unsigned int maxdata;
 	comedi_range *rng;
 	int ret;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	options.subdevice = -1;
+	parse_options(&options, argc, argv);
 
 	/* Force n_chan to be 1 */
-	n_chan = 1;
+	options.n_chan = 1;
 
-	if(value){
-		waveform_frequency = value;
+	if(options.value){
+		waveform_frequency = options.value;
 	}
 
-	dev = comedi_open(filename);
+	dev = comedi_open(options.filename);
 	if(dev == NULL){
-		fprintf(stderr, "error opening %s\n", filename);
+		fprintf(stderr, "error opening %s\n", options.filename);
 		return -1;
 	}
-	subdevice = comedi_find_subdevice_by_type(dev,COMEDI_SUBD_AO,0);
+	if(options.subdevice < 0)
+		options.subdevice = comedi_find_subdevice_by_type(dev, COMEDI_SUBD_AO, 0);
 
-	maxdata = comedi_get_maxdata(dev,subdevice,0);
-	rng = comedi_get_range(dev,subdevice,0,0);
+	maxdata = comedi_get_maxdata(dev, options.subdevice, 0);
+	rng = comedi_get_range(dev, options.subdevice, 0, 0);
 
-	offset = (double)comedi_from_phys(0.0,rng,maxdata);
-	amplitude = (double)comedi_from_phys(1.0,rng,maxdata) - offset;
+	offset = (double)comedi_from_phys(0.0, rng, maxdata);
+	amplitude = (double)comedi_from_phys(1.0, rng, maxdata) - offset;
 
 	memset(&cmd,0,sizeof(cmd));
-	cmd.subdev = subdevice;
+	cmd.subdev = options.subdevice;
 	cmd.flags = 0;
 	cmd.start_src = TRIG_INT;
 	cmd.start_arg = 0;
 	cmd.scan_begin_src = TRIG_TIMER;
-	cmd.scan_begin_arg = 1e9/freq;
+	cmd.scan_begin_arg = 1e9 / options.freq;
 	cmd.convert_src = TRIG_NOW;
 	cmd.convert_arg = 0;
 	cmd.scan_end_src = TRIG_COUNT;
-	cmd.scan_end_arg = n_chan;
+	cmd.scan_end_arg = options.n_chan;
 	cmd.stop_src = TRIG_NONE;
 	cmd.stop_arg = 0;
 
 	cmd.chanlist = chanlist;
-	cmd.chanlist_len = n_chan;
+	cmd.chanlist_len = options.n_chan;
 
-	chanlist[0] = CR_PACK(channel,range,aref);
-	chanlist[1] = CR_PACK(channel+1,range,aref);
+	chanlist[0] = CR_PACK(options.channel, options.range, options.aref);
+	chanlist[1] = CR_PACK(options.channel + 1, options.range, options.aref);
 
-	dds_init();
+	dds_init(waveform_frequency, options.freq);
 
 	dump_cmd(stdout,&cmd);
 
@@ -191,8 +194,8 @@ int main(int argc, char *argv[])
 	}
 	printf("m=%d\n",m);
 
-	ret = comedi_internal_trigger(dev, subdevice, 0);
-	if(ret<0){
+	ret = comedi_internal_trigger(dev, options.subdevice, 0);
+	if(ret < 0){
 		perror("comedi_internal_trigger\n");
 		exit(1);
 	}
@@ -228,9 +231,9 @@ sampl_t waveform[WAVEFORM_LEN];
 unsigned int acc;
 unsigned int adder;
 
-void dds_init(void)
+void dds_init(double waveform_frequency, double update_frequency)
 {
-	adder=waveform_frequency/freq*(1<<16)*(1<<WAVEFORM_SHIFT);
+	adder = waveform_frequency / update_frequency * (1 << 16) * (1 << WAVEFORM_SHIFT);
 
 	dds_init_function();
 }
diff --git a/demo/apply_cal.c b/demo/apply_cal.c
index 4c105c9..630c3fe 100644
--- a/demo/apply_cal.c
+++ b/demo/apply_cal.c
@@ -1,5 +1,5 @@
 /*
- * demo for changing between different calibrations
+ * demo for changing between different (hardware-based) calibrations
  * Part of Comedilib
  *
  * Copyright (c) 1999,2000 David A. Schleef <ds@schleef.org>
@@ -29,24 +29,26 @@ int main(int argc, char *argv[])
 {
 	lsampl_t data;
 	int ret;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device=comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	data = value; 
-	if(verbose){
+	data = options.value;
+	if(options.verbose){
 		printf("writing %d to device=%s subdevice=%d channel=%d range=%d analog reference=%d\n",
-			data,filename,subdevice,channel,range,aref);
+			data, options.filename, options.subdevice, options.channel, options.range, options.aref);
 	}
 
-	ret=comedi_apply_calibration(device,subdevice,channel,range,aref,NULL);
-	if(ret<0){
-		comedi_perror(filename);
+	ret = comedi_apply_calibration(device, options.subdevice, options.channel, options.range, options.aref, NULL);
+	if(ret < 0){
+		comedi_perror(options.filename);
 		exit(0);
 	}
 
diff --git a/demo/choose_clock.c b/demo/choose_clock.c
index eae42f3..58ed44f 100644
--- a/demo/choose_clock.c
+++ b/demo/choose_clock.c
@@ -34,20 +34,24 @@ int main(int argc, char *argv[])
 {
 	unsigned period_ns;
 	int retval;
+	lsampl_t clock_selection;
+	struct parsed_options options;
 
-	freq = 0.;
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	options.freq = 0.;
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
-	if(freq > 0.)
-		period_ns = 1e9 / freq;
+	if(options.freq > 0.)
+		period_ns = 1e9 / options.freq;
 	else
 		period_ns = 0;
-	printf("Selecting master clock %d on subdevice %d.\n", value, subdevice);
+	clock_selection = options.value;
+	printf("Selecting master clock %d on subdevice %d.\n", clock_selection, options.subdevice);
 	if(period_ns)
 	{
 		printf("Clock period = %d nanoseconds.\n", period_ns);
@@ -59,11 +63,11 @@ int main(int argc, char *argv[])
 	lsampl_t data[3];
 	memset(&insn, 0, sizeof(comedi_insn));
 	insn.insn = INSN_CONFIG;
-	insn.subdev = subdevice;
+	insn.subdev = options.subdevice;
 	insn.data = data;
 	insn.n = sizeof(data) / sizeof(data[0]);
 	data[0] = INSN_CONFIG_SET_CLOCK_SRC;
-	data[1] = value;
+	data[1] = clock_selection;
 	data[2] = period_ns;
 
 	retval = comedi_do_insn(device, &insn);
diff --git a/demo/choose_routing.c b/demo/choose_routing.c
index 4e137b6..1aa6b10 100644
--- a/demo/choose_routing.c
+++ b/demo/choose_routing.c
@@ -34,30 +34,34 @@ int main(int argc, char *argv[])
 {
 	unsigned period_ns;
 	int retval;
+	lsampl_t routing;
+	struct parsed_options options;
 
-	freq = 0.;
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	options.freq = 0.;
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
-	if(freq > 0.)
-		period_ns = 1e9 / freq;
+	if(options.freq > 0.)
+		period_ns = 1e9 / options.freq;
 	else
 		period_ns = 0;
-	printf("Selecting routing %d for channel %d on subdevice %d.\n", value, channel, subdevice);
+	routing = options.value;
+	printf("Selecting routing %d for channel %d on subdevice %d.\n", routing, options.channel, options.subdevice);
 	comedi_insn insn;
 	lsampl_t data[2];
 	memset(&insn, 0, sizeof(comedi_insn));
 	insn.insn = INSN_CONFIG;
-	insn.subdev = subdevice;
-	insn.chanspec = channel;
+	insn.subdev = options.subdevice;
+	insn.chanspec = options.channel;
 	insn.data = data;
 	insn.n = sizeof(data) / sizeof(data[0]);
 	data[0] = INSN_CONFIG_SET_ROUTING;
-	data[1] = value;
+	data[1] = routing;
 
 	retval = comedi_do_insn(device, &insn);
 	if(retval < 0) comedi_perror("comedi_do_insn");
diff --git a/demo/cmd.c b/demo/cmd.c
index ee0ad8c..51b7e3c 100644
--- a/demo/cmd.c
+++ b/demo/cmd.c
@@ -34,12 +34,12 @@ static comedi_range * range_info[N_CHANS];
 static lsampl_t maxdata[N_CHANS];
 
 
-int prepare_cmd_lib(comedi_t *dev,int subdevice,comedi_cmd *cmd);
-int prepare_cmd(comedi_t *dev,int subdevice,comedi_cmd *cmd);
+int prepare_cmd_lib(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd);
+int prepare_cmd_lib(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd);
 
 void do_cmd(comedi_t *dev,comedi_cmd *cmd);
 
-void print_datum(lsampl_t raw, int i);
+void print_datum(lsampl_t raw, int channel_index, short physical);
 
 char *cmdtest_messages[]={
 	"success",
@@ -60,26 +60,28 @@ int main(int argc, char *argv[])
 	struct timeval start,end;
 	int subdev_flags;
 	lsampl_t raw;
-	
-	parse_options(argc,argv);
+	struct parsed_options options;
 
-	/* The following global variables used in this demo are
-	 * defined in common.c, and can be modified by command line
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
+
+	/* The following variables used in this demo
+	 * can be modified by command line
 	 * options.  When modifying this demo, you may want to
 	 * change them here. */
-	//filename = "/dev/comedi0";
-	//subdevice = 0;
-	//channel = 0;
-	//range = 0;
-	//aref = AREF_GROUND;
-	//n_chan = 4;
-	//n_scan = 1000;
-	//freq = 1000.0;
+	//options.filename = "/dev/comedi0";
+	//options.subdevice = 0;
+	//options.channel = 0;
+	//options.range = 0;
+	//options.aref = AREF_GROUND;
+	//options.n_chan = 4;
+	//options.n_scan = 1000;
+	//options.freq = 1000.0;
 
 	/* open the device */
-	dev = comedi_open(filename);
+	dev = comedi_open(options.filename);
 	if(!dev){
-		comedi_perror(filename);
+		comedi_perror(options.filename);
 		exit(1);
 	}
 
@@ -87,20 +89,20 @@ int main(int argc, char *argv[])
 	comedi_set_global_oor_behavior(COMEDI_OOR_NUMBER);
 
 	/* Set up channel list */
-	for(i=0;i<n_chan;i++){
-		chanlist[i]=CR_PACK(channel+i,range,aref);
-		range_info[i]=comedi_get_range(dev,subdevice,channel,range);
-		maxdata[i]=comedi_get_maxdata(dev,subdevice,channel);
+	for(i = 0; i < options.n_chan; i++){
+		chanlist[i] = CR_PACK(options.channel + i, options.range, options.aref);
+		range_info[i] = comedi_get_range(dev, options.subdevice, options.channel, options.range);
+		maxdata[i] = comedi_get_maxdata(dev, options.subdevice, options.channel);
 	}
 
 	/* prepare_cmd_lib() uses a Comedilib routine to find a
 	 * good command for the device.  prepare_cmd() explicitly
 	 * creates a command, which may not work for your device. */
-	prepare_cmd_lib(dev,subdevice,cmd);
-	//prepare_cmd(dev,subdevice,cmd);
-	
-	fprintf(stderr,"command before testing:\n");
-	dump_cmd(stderr,cmd);
+	prepare_cmd_lib(dev, options.subdevice, options.n_scan, options.n_chan, 1e9 / options.freq, cmd);
+	//prepare_cmd(dev, options.subdevice, options.n_scan, options.n_chan, 1e9 / options.freq, cmd);
+
+	fprintf(stderr, "command before testing:\n");
+	dump_cmd(stderr, cmd);
 
 	/* comedi_command_test() tests a command to see if the
 	 * trigger sources and arguments are valid for the subdevice.
@@ -112,56 +114,56 @@ int main(int argc, char *argv[])
 	 * can test it multiple times until it passes.  Typically,
 	 * if you can't get a valid command in two tests, the original
 	 * command wasn't specified very well. */
-	ret = comedi_command_test(dev,cmd);
-	if(ret<0){
+	ret = comedi_command_test(dev, cmd);
+	if(ret < 0){
 		comedi_perror("comedi_command_test");
-		if(errno==EIO){
+		if(errno == EIO){
 			fprintf(stderr,"Ummm... this subdevice doesn't support commands\n");
 		}
 		exit(1);
 	}
-	fprintf(stderr,"first test returned %d (%s)\n",ret,
+	fprintf(stderr,"first test returned %d (%s)\n", ret,
 			cmdtest_messages[ret]);
-	dump_cmd(stderr,cmd);
+	dump_cmd(stderr, cmd);
 
-	ret = comedi_command_test(dev,cmd);
-	if(ret<0){
+	ret = comedi_command_test(dev, cmd);
+	if(ret < 0){
 		comedi_perror("comedi_command_test");
 		exit(1);
 	}
-	fprintf(stderr,"second test returned %d (%s)\n",ret,
+	fprintf(stderr,"second test returned %d (%s)\n", ret,
 			cmdtest_messages[ret]);
 	if(ret!=0){
-		dump_cmd(stderr,cmd);
-		fprintf(stderr,"Error preparing command\n");
+		dump_cmd(stderr, cmd);
+		fprintf(stderr, "Error preparing command\n");
 		exit(1);
 	}
 
 	/* this is only for informational purposes */
-	gettimeofday(&start,NULL);
-	fprintf(stderr,"start time: %ld.%06ld\n",start.tv_sec,start.tv_usec);
+	gettimeofday(&start, NULL);
+	fprintf(stderr,"start time: %ld.%06ld\n", start.tv_sec, start.tv_usec);
 
 	/* start the command */
-	ret=comedi_command(dev,cmd);
-	if(ret<0){
+	ret = comedi_command(dev, cmd);
+	if(ret < 0){
 		comedi_perror("comedi_command");
 		exit(1);
 	}
-	subdev_flags = comedi_get_subdevice_flags(dev, subdevice);
+	subdev_flags = comedi_get_subdevice_flags(dev, options.subdevice);
 	while(1){
-		ret=read(comedi_fileno(dev),buf,BUFSZ);
-		if(ret<0){
+		ret = read(comedi_fileno(dev),buf,BUFSZ);
+		if(ret < 0){
 			/* some error occurred */
 			perror("read");
 			break;
-		}else if(ret==0){
+		}else if(ret == 0){
 			/* reached stop condition */
 			break;
 		}else{
 			static int col = 0;
 			int bytes_per_sample;
-			total+=ret;
-			if(verbose)fprintf(stderr,"read %d %d\n",ret,total);
+			total += ret;
+			if(options.verbose)fprintf(stderr, "read %d %d\n", ret, total);
 			if(subdev_flags & SDF_LSAMPL)
 				bytes_per_sample = sizeof(lsampl_t);
 			else
@@ -172,9 +174,9 @@ int main(int argc, char *argv[])
 				} else {
 					raw = ((sampl_t *)buf)[i];
 				}
-				print_datum(raw,col);
+				print_datum(raw, col, options.physical);
 				col++;
-				if(col==n_chan){
+				if(col == options.n_chan){
 					printf("\n");
 					col=0;
 				}
@@ -184,15 +186,15 @@ int main(int argc, char *argv[])
 
 	/* this is only for informational purposes */
 	gettimeofday(&end,NULL);
-	fprintf(stderr,"end time: %ld.%06ld\n",end.tv_sec,end.tv_usec);
+	fprintf(stderr,"end time: %ld.%06ld\n", end.tv_sec, end.tv_usec);
 
-	end.tv_sec-=start.tv_sec;
-	if(end.tv_usec<start.tv_usec){
+	end.tv_sec -= start.tv_sec;
+	if(end.tv_usec < start.tv_usec){
 		end.tv_sec--;
-		end.tv_usec+=1000000;
+		end.tv_usec += 1000000;
 	}
-	end.tv_usec-=start.tv_usec;
-	fprintf(stderr,"time: %ld.%06ld\n",end.tv_sec,end.tv_usec);
+	end.tv_usec -= start.tv_usec;
+	fprintf(stderr,"time: %ld.%06ld\n", end.tv_sec, end.tv_usec);
 
 	return 0;
 }
@@ -201,7 +203,7 @@ int main(int argc, char *argv[])
  * This prepares a command in a pretty generic way.  We ask the
  * library to create a stock command that supports periodic
  * sampling of data, then modify the parts we want. */
-int prepare_cmd_lib(comedi_t *dev,int subdevice,comedi_cmd *cmd)
+int prepare_cmd_lib(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd)
 {
 	int ret;
 
@@ -210,18 +212,18 @@ int prepare_cmd_lib(comedi_t *dev,int subdevice,comedi_cmd *cmd)
 	/* This comedilib function will get us a generic timed
 	 * command for a particular board.  If it returns -1,
 	 * that's bad. */
-	ret = comedi_get_cmd_generic_timed(dev,subdevice,cmd,1e9/freq);
+	ret = comedi_get_cmd_generic_timed(dev, subdevice,cmd, period_nanosec);
 	if(ret<0){
 		printf("comedi_get_cmd_generic_timed failed\n");
 		return ret;
 	}
 
 	/* Modify parts of the command */
-	cmd->chanlist		= chanlist;
-	cmd->chanlist_len	= n_chan;
+	cmd->chanlist = chanlist;
+	cmd->chanlist_len = n_chan;
 
 	cmd->scan_end_arg = n_chan;
-	if(cmd->stop_src==TRIG_COUNT)cmd->stop_arg = n_scan;
+	if(cmd->stop_src == TRIG_COUNT) cmd->stop_arg = n_scan;
 
 	return 0;
 }
@@ -230,7 +232,7 @@ int prepare_cmd_lib(comedi_t *dev,int subdevice,comedi_cmd *cmd)
  * Set up a command by hand.  This will not work on some devices.
  * There is no single command that will work on all devices.
  */
-int prepare_cmd(comedi_t *dev,int subdevice,comedi_cmd *cmd)
+int prepare_cmd(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd)
 {
 	memset(cmd,0,sizeof(*cmd));
 
@@ -242,7 +244,7 @@ int prepare_cmd(comedi_t *dev,int subdevice,comedi_cmd *cmd)
 
 	/* Wake up at the end of every scan */
 	//cmd->flags |= TRIG_WAKE_EOS;
-	
+
 	/* Use a real-time interrupt, if available */
 	//cmd->flags |= TRIG_RT;
 
@@ -283,7 +285,7 @@ int prepare_cmd(comedi_t *dev,int subdevice,comedi_cmd *cmd)
 	 * by the device, but it will be adjusted to the nearest supported
 	 * value by comedi_command_test(). */
 	cmd->scan_begin_src =	TRIG_TIMER;
-	cmd->scan_begin_arg =	1e9/freq;		/* in ns */
+	cmd->scan_begin_arg = period_nanosec;		/* in ns */
 
 	/* The timing between each sample in a scan is controlled by convert.
 	 * TRIG_TIMER:   Conversion events occur periodically.
@@ -325,12 +327,12 @@ int prepare_cmd(comedi_t *dev,int subdevice,comedi_cmd *cmd)
 	return 0;
 }
 
-void print_datum(lsampl_t raw, int i) {
+void print_datum(lsampl_t raw, int channel_index, short physical) {
 	double physical_value;
 	if(!physical) {
 		printf("%d ",raw);
 	} else {
-		physical_value = comedi_to_phys(raw,range_info[i],maxdata[i]);
+		physical_value = comedi_to_phys(raw, range_info[channel_index], maxdata[channel_index]);
 		printf("%#8.6g ",physical_value);
 	}
 }
diff --git a/demo/common.c b/demo/common.c
index c9cef46..c22470b 100644
--- a/demo/common.c
+++ b/demo/common.c
@@ -15,69 +15,67 @@
 #include <stdlib.h>
 #include "examples.h"
 
+static char * const default_filename = "/dev/comedi0";
 
-char *filename="/dev/comedi0";
-int verbose = 0;
-
-int value=0;
-int subdevice=0;
-int channel=0;
-int aref=AREF_GROUND;
-int range=0;
-int n_chan=4;
-int n_scan=1000;
-double freq=1000.0;
-int physical = 0;
-
+void init_parsed_options(struct parsed_options *options)
+{
+	memset(options, 0, sizeof(struct parsed_options));
+	options->filename = default_filename;
+	options->aref = AREF_GROUND;
+	options->n_chan = 4;
+	options->n_scan = 1000;
+	options->freq = 1000.0;
+	options->physical = 0;
+	options->value = 0.;
+}
 
-int parse_options(int argc, char *argv[])
+int parse_options(struct parsed_options *options, int argc, char *argv[])
 {
 	int c;
 
-
 	while (-1 != (c = getopt(argc, argv, "a:c:s:r:f:n:N:F:pvdgom"))) {
 		switch (c) {
 		case 'f':
-			filename = optarg;
+			options->filename = optarg;
 			break;
 		case 's':
-			subdevice = strtoul(optarg,NULL,0);
+			options->subdevice = strtoul(optarg, NULL, 0);
 			break;
 		case 'c':
-			channel = strtoul(optarg,NULL,0);
+			options->channel = strtoul(optarg, NULL, 0);
 			break;
 		case 'a':
-			aref = strtoul(optarg,NULL,0);
+			options->aref = strtoul(optarg, NULL, 0);
 			break;
 		case 'r':
-			range = strtoul(optarg,NULL,0);
+			options->range = strtoul(optarg, NULL, 0);
 			break;
 		case 'n':
-			n_chan = strtoul(optarg,NULL,0);
+			options->n_chan = strtoul(optarg, NULL, 0);
 			break;
 		case 'N':
-			n_scan = strtoul(optarg,NULL,0);
+			options->n_scan = strtoul(optarg, NULL, 0);
 			break;
 		case 'F':
-			freq = strtoul(optarg,NULL,0);
+			options->freq = strtod(optarg, NULL);
 			break;
 		case 'p':
-			physical = 1;
+			options->physical = 1;
 			break;
 		case 'v':
-			verbose = 1;
+			++options->verbose;
 			break;
 		case 'd':
-			aref = AREF_DIFF;
+			options->aref = AREF_DIFF;
 			break;
 		case 'g':
-			aref = AREF_GROUND;
+			options->aref = AREF_GROUND;
 			break;
 		case 'o':
-			aref = AREF_OTHER;
+			options->aref = AREF_OTHER;
 			break;
 		case 'm':
-			aref = AREF_COMMON;
+			options->aref = AREF_COMMON;
 			break;
 		default:
 			printf("bad option\n");
@@ -86,7 +84,7 @@ int parse_options(int argc, char *argv[])
 	}
 	if(optind < argc) {
 		/* data value */
-		sscanf(argv[optind++],"%d",&value);
+		options->value = strtod(argv[optind++], NULL);
 	}
 
 	return argc;
diff --git a/demo/dio.c b/demo/dio.c
index 51425af..5c39117 100644
--- a/demo/dio.c
+++ b/demo/dio.c
@@ -31,30 +31,32 @@ int main(int argc, char *argv[])
 {
 	int ret;
 	int stype;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	stype = comedi_get_subdevice_type(device,subdevice);
-	if(stype!=COMEDI_SUBD_DIO){
-		printf("%d is not a digital I/O subdevice\n",subdevice);
-		exit(0);
+	stype = comedi_get_subdevice_type(device, options.subdevice);
+	if(stype != COMEDI_SUBD_DIO){
+		printf("%d is not a digital I/O subdevice\n", options.subdevice);
+		exit(-1);
 	}
 
-	printf("configuring pin %d or subdevice %d ", channel, subdevice);
-	if(value)
+	printf("configuring pin %d or subdevice %d ", options.channel, options.subdevice);
+	if(options.value)
 	{
 		printf("for output.\n");
-		ret=comedi_dio_config(device,subdevice,channel, COMEDI_OUTPUT);
+		ret = comedi_dio_config(device, options.subdevice, options.channel, COMEDI_OUTPUT);
 	}else
 	{
 		printf("for input.\n");
-		ret=comedi_dio_config(device,subdevice,channel, COMEDI_INPUT);
+		ret = comedi_dio_config(device, options.subdevice, options.channel, COMEDI_INPUT);
 	}
 	return 0;
 }
diff --git a/demo/eeprom_dump.c b/demo/eeprom_dump.c
index 3168666..f104d97 100644
--- a/demo/eeprom_dump.c
+++ b/demo/eeprom_dump.c
@@ -12,7 +12,7 @@
 #include <stdlib.h>
 #include "examples.h"
 
-int read_eeprom(comedi_t *it,unsigned int **eeprom);
+int read_eeprom(comedi_t *it,unsigned int **eeprom, struct parsed_options options);
 void dump_eeprom(unsigned int *eeprom,int len);
 
 comedi_t *device;
@@ -21,16 +21,19 @@ int main(int argc, char *argv[])
 {
 	int len;
 	unsigned int *eeprom;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	options.subdevice = -1;
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	len=read_eeprom(device,&eeprom);
+	len = read_eeprom(device, &eeprom, options);
 	dump_eeprom(eeprom,len);
 
 	return 0;
@@ -39,33 +42,36 @@ int main(int argc, char *argv[])
 
 
 
-int read_eeprom(comedi_t *it,unsigned int **eeprom)
+int read_eeprom(comedi_t *it, unsigned int **eeprom, struct parsed_options options)
 {
-	int subd;
 	int n,i,ret;
 	lsampl_t data;
 	unsigned int *ptr;
 	lsampl_t maxdata;
 
-	subd=comedi_find_subdevice_by_type(it,COMEDI_SUBD_MEMORY,0);
-	if(subd<0){
-		fprintf(stderr,"No memory subdevice\n");
-		return 0;
+	if(options.subdevice < 0)
+	{
+		options.subdevice = comedi_find_subdevice_by_type(it, COMEDI_SUBD_MEMORY, 0);
+		if(options.subdevice < 0){
+			fprintf(stderr,"No memory subdevice\n");
+			return 0;
+		}
 	}
 
-	n=comedi_get_n_channels(it,subd);
-	maxdata=comedi_get_maxdata(it,subd,0);
+	n = comedi_get_n_channels(it, options.subdevice);
+	maxdata = comedi_get_maxdata(it, options.subdevice, 0);
 
-	if(maxdata!=0xff){
-		fprintf(stderr,"Memory subdevice has strange maxdata, aborting\n");
+	if(maxdata != 0xff){
+		fprintf(stderr,"Demo only supports 8-bit memory subdevice has strange maxdata, aborting\n");
+		exit(-1);
 	}
 
-	ptr=malloc(sizeof(unsigned int)*n);
+	ptr = malloc(sizeof(unsigned int) * n);
 
-	for(i=0;i<n;i++){
-		ret=comedi_data_read(it,subd,i,0,0,&data);
-		ptr[i]=data;
-		if(ret<0){
+	for(i = 0; i < n; i++){
+		ret = comedi_data_read(it, options.subdevice, i, 0, 0, &data);
+		ptr[i] = data;
+		if(ret < 0){
 			comedi_perror("comedi_data_read");
 			return 0;
 		}
diff --git a/demo/examples.h b/demo/examples.h
index 5e9e527..37bd87e 100644
--- a/demo/examples.h
+++ b/demo/examples.h
@@ -8,24 +8,27 @@
  * Definitions of some of the common code.
  */
 
-extern char *filename;
-extern int verbose_flag;
 extern comedi_t *device;
 
-extern int value;
-extern int subdevice;
-extern int channel;
-extern int aref;
-extern int range;
-extern int physical;
-extern int verbose;
-extern int n_chan;
-extern int n_scan;
-extern double freq;
-
-int parse_options(int argc, char *argv[]);
-char *cmd_src(int src,char *buf);
-void dump_cmd(FILE *file,comedi_cmd *cmd);
+struct parsed_options
+{
+	char *filename;
+	double value;
+	int subdevice;
+	int channel;
+	int aref;
+	int range;
+	int physical;
+	int verbose;
+	int n_chan;
+	int n_scan;
+	double freq;
+};
+
+extern void init_parsed_options(struct parsed_options *options);
+extern int parse_options(struct parsed_options *options, int argc, char *argv[]);
+extern char *cmd_src(int src,char *buf);
+extern void dump_cmd(FILE *file,comedi_cmd *cmd);
 
 
 #define sec_to_nsec(x) ((x)*1000000000)
diff --git a/demo/info.c b/demo/info.c
index 5964dcc..dd717fe 100644
--- a/demo/info.c
+++ b/demo/info.c
@@ -49,24 +49,26 @@ int main(int argc,char *argv[])
 	int n_ranges;
 	int subdev_flags;
 	comedi_range *rng;
-	
-	parse_options(argc,argv);
+	struct parsed_options options;
 
-	it=comedi_open(filename);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
+
+	it = comedi_open(options.filename);
 	if(!it){
-		comedi_perror(filename);
+		comedi_perror(options.filename);
 		exit(1);
 	}
 
 	printf("overall info:\n");
-	printf("  version code: 0x%06x\n",comedi_get_version_code(it));
-	printf("  driver name: %s\n",comedi_get_driver_name(it));
-	printf("  board name: %s\n",comedi_get_board_name(it));
-	printf("  number of subdevices: %d\n",n_subdevices=comedi_get_n_subdevices(it));
-	
-	for(i=0;i<n_subdevices;i++){
+	printf("  version code: 0x%06x\n", comedi_get_version_code(it));
+	printf("  driver name: %s\n", comedi_get_driver_name(it));
+	printf("  board name: %s\n", comedi_get_board_name(it));
+	printf("  number of subdevices: %d\n", n_subdevices = comedi_get_n_subdevices(it));
+
+	for(i = 0; i < n_subdevices; i++){
 		printf("subdevice %d:\n",i);
-		type=comedi_get_subdevice_type(it,i);
+		type = comedi_get_subdevice_type(it, i);
 		printf("  type: %d (%s)\n",type,subdevice_types[type]);
 		if(type==COMEDI_SUBD_UNUSED)
 			continue;
@@ -106,7 +108,7 @@ int main(int argc,char *argv[])
 		printf("  command:\n");
 		get_command_stuff(it,i);
 	}
-	
+
 	return 0;
 }
 
@@ -114,11 +116,11 @@ char *tobinary(char *s,int bits,int n)
 {
 	int bit=1<<n;
 	char *t=s;
-	
+
 	for(;bit;bit>>=1)
 		*t++=(bits&bit)?'1':'0';
 	*t=0;
-	
+
 	return s;
 }
 
@@ -137,7 +139,7 @@ void get_command_stuff(comedi_t *it,int s)
 		printf("    convert: %s\n",cmd_src(cmd.convert_src,buf));
 		printf("    scan_end: %s\n",cmd_src(cmd.scan_end_src,buf));
 		printf("    stop: %s\n",cmd_src(cmd.stop_src,buf));
-	
+
 		probe_max_1chan(it,s);
 	}
 }
diff --git a/demo/inp.c b/demo/inp.c
index bd8baea..1719ed3 100644
--- a/demo/inp.c
+++ b/demo/inp.c
@@ -33,40 +33,42 @@ int main(int argc, char *argv[])
 	comedi_range * range_info;
 	lsampl_t maxdata;
 	double physical_value;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	if(verbose){
+	if(options.verbose){
 		printf("measuring device=%s subdevice=%d channel=%d range=%d analog reference=%d\n",
-			filename,subdevice,channel,range,aref);
+			options.filename, options.subdevice, options.channel, options.range, options.aref);
 	}
 
-	ret=comedi_data_read(device,subdevice,channel,range,aref,&data);
-	if(ret<0){
-		comedi_perror(filename);
-		exit(0);
+	ret = comedi_data_read(device, options.subdevice, options.channel, options.range, options.aref, &data);
+	if(ret < 0){
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	if(physical) {
+	if(options.physical) {
 		comedi_set_global_oor_behavior(COMEDI_OOR_NAN);
-		range_info = comedi_get_range(device,subdevice,channel,range);
-		maxdata = comedi_get_maxdata(device,subdevice,channel);
-		if(verbose) {
+		range_info = comedi_get_range(device, options.subdevice, options.channel, options.range);
+		maxdata = comedi_get_maxdata(device, options.subdevice, options.channel);
+		if(options.verbose) {
 			printf("[0,%d] -> [%g,%g]\n", maxdata,
 				range_info->min, range_info->max);
 		}
-		physical_value = comedi_to_phys(data,range_info,maxdata);
+		physical_value = comedi_to_phys(data, range_info, maxdata);
 		if(isnan(physical_value)) {
 			printf("Out of range [%g,%g]",
 				range_info->min, range_info->max);
 		} else {
-			printf("%g",physical_value);
+			printf("%g", physical_value);
 			switch(range_info->unit) {
 				case UNIT_volt: printf(" V"); break;
 				case UNIT_mA: printf(" mA"); break;
@@ -74,7 +76,7 @@ int main(int argc, char *argv[])
 				default: printf(" (unknown unit %d)",
 					range_info->unit);
 			}
-			if(verbose) {
+			if(options.verbose) {
 				printf(" (%d raw units)", data);
 			}
 		}
diff --git a/demo/inpn.c b/demo/inpn.c
index 2676810..82e6e2f 100644
--- a/demo/inpn.c
+++ b/demo/inpn.c
@@ -36,36 +36,40 @@ int main(int argc, char *argv[])
 	int maxdata;
 	lsampl_t data;
 	double voltage;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	options.subdevice = -1;
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	subdevice=comedi_find_subdevice_by_type(device,COMEDI_SUBD_AI,0);
-	if(subdevice<0){
-		printf("no analog input subdevice found\n");
-		exit(0);
+	if(options.subdevice < 0)
+	{
+		options.subdevice = comedi_find_subdevice_by_type(device, COMEDI_SUBD_AI, 0);
+		if(options.subdevice<0){
+			printf("no analog input subdevice found\n");
+			exit(-1);
+		}
 	}
+	n_chans = comedi_get_n_channels(device, options.subdevice);
+	for(chan = 0; chan < n_chans; ++chan){
+		printf("%d: ", chan);
 
-	n_chans=comedi_get_n_channels(device,subdevice);
-	for(chan=0;chan<n_chans;chan++){
-		printf("%d: ",chan);
-
-		n_ranges=comedi_get_n_ranges(device,subdevice,chan);
+		n_ranges = comedi_get_n_ranges(device, options.subdevice, chan);
 
-		maxdata=comedi_get_maxdata(device,subdevice,chan);
-		for(range=0;range<n_ranges;range++){
-			comedi_data_read(device,subdevice,chan,range,aref,&data);
-			voltage=comedi_to_phys(data,comedi_get_range(device,subdevice,chan,range),maxdata);
-			printf("%g ",voltage);
+		maxdata = comedi_get_maxdata(device, options.subdevice, chan);
+		for(range = 0; range < n_ranges; range++){
+			comedi_data_read(device, options.subdevice, chan, options.range, options.aref, &data);
+			voltage = comedi_to_phys(data, comedi_get_range(device, options.subdevice, chan, options.range), maxdata);
+			printf("%g ", voltage);
 		}
 		printf("\n");
 	}
-	
-	exit(0);
+	return 0;
 }
 
diff --git a/demo/insn.c b/demo/insn.c
index 33978bc..b842d04 100644
--- a/demo/insn.c
+++ b/demo/insn.c
@@ -9,7 +9,7 @@
  * source code.
  */
 /*
-   This example shows how to use instructions, i.e., comedi_insns.  
+   This example shows how to use instructions, i.e., comedi_insns.
 
    Using instructions directly, as in this example, is not recommended
    for the beginner.  Use the higher-level functions such as
@@ -47,23 +47,25 @@ int main(int argc, char *argv[])
 	comedi_insnlist il;
 	struct timeval t1,t2;
 	lsampl_t data[MAX_SAMPLES];
+	struct parsed_options options;
 
-	n_scan = 10;	/* override default n_scan value to something more suitable */
-	parse_options(argc,argv);
-	if( n_scan > MAX_SAMPLES ){
+	init_parsed_options(&options);
+	options.n_scan = 10;	/* override default n_scan value to something more suitable */
+	parse_options(&options, argc, argv);
+	if(options.n_scan > MAX_SAMPLES ){
 		fprintf( stderr, "Requested too many samples, reducing to %i\n", MAX_SAMPLES );
-		n_scan = MAX_SAMPLES;
+		options.n_scan = MAX_SAMPLES;
 	}
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	if(verbose){
+	if(options.verbose){
 		printf("measuring device=%s subdevice=%d channel=%d range=%d analog reference=%d\n",
-			filename,subdevice,channel,range,aref);
+			options.filename, options.subdevice, options.channel, options.range, options.aref);
 	}
 
 	/* Set up a the "instruction list", which is just a pointer
@@ -79,10 +81,10 @@ int main(int argc, char *argv[])
 
 	/* Instruction 1: do 10 analog input reads */
 	insn[1].insn=INSN_READ;
-	insn[1].n=n_scan;
+	insn[1].n = options.n_scan;
 	insn[1].data=data;
-	insn[1].subdev=subdevice;
-	insn[1].chanspec=CR_PACK(channel,range,aref);
+	insn[1].subdev = options.subdevice;
+	insn[1].chanspec=CR_PACK(options.channel, options.range, options.aref);
 
 	/* Instruction 2: perform a gettimeofday() */
 	insn[2].insn=INSN_GTOD;
@@ -91,18 +93,18 @@ int main(int argc, char *argv[])
 
 	ret=comedi_do_insnlist(device,&il);
 	if(ret<0){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	printf("initial time: %ld.%06ld\n",t1.tv_sec,t1.tv_usec);
-	for(i=0;i<n_scan;i++){
-		printf("%d\n",data[i]);
+	printf("initial time: %ld.%06ld\n", t1.tv_sec, t1.tv_usec);
+	for(i = 0; i < options.n_scan; i++){
+		printf("%d\n", data[i]);
 	}
-	printf("final time: %ld.%06ld\n",t2.tv_sec,t2.tv_usec);
+	printf("final time: %ld.%06ld\n", t2.tv_sec, t2.tv_usec);
 
-	printf("difference (us): %ld\n",(t2.tv_sec-t1.tv_sec)*1000000+
-			(t2.tv_usec-t1.tv_usec));
+	printf("difference (us): %ld\n",(t2.tv_sec-t1.tv_sec) * 1000000 +
+			(t2.tv_usec - t1.tv_usec));
 
 	return 0;
 }
diff --git a/demo/ledclock.c b/demo/ledclock.c
index 53f262a..477fcf1 100644
--- a/demo/ledclock.c
+++ b/demo/ledclock.c
@@ -10,7 +10,7 @@
  */
 
 /*
- * Requirements:  
+ * Requirements:
  *    - A board with a digital output subdevice and a subdevice that
  *      can trigger on an external digital line.  A parallel port
  *      satisfies these requirements.
@@ -58,7 +58,7 @@ sampl_t buf[BUFSZ];
 unsigned int chanlist[16];
 
 
-void prepare_cmd(comedi_t *dev,comedi_cmd *cmd);
+void prepare_cmd(comedi_t *dev,comedi_cmd *cmd, int subdevice);
 void do_cmd(comedi_t *dev,comedi_cmd *cmd);
 void do_toggle(void);
 
@@ -125,19 +125,19 @@ void do_toggle(void)
 
 int main(int argc, char *argv[])
 {
-	char *fn = NULL;
 	int ret;
 	comedi_cmd cmd;
+	struct parsed_options options;
 
-	fn = "/dev/comedi1";
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device = comedi_open(fn);
+	device = comedi_open(options.filename);
 	if(!device){
-		perror(fn);
+		perror(options.filename);
 		exit(1);
 	}
 
-	subdevice = 3;
 	out_subd = 0;
 
 	config_output();
@@ -156,7 +156,7 @@ int main(int argc, char *argv[])
 	}
 #endif
 
-	prepare_cmd(device,&cmd);
+	prepare_cmd(device, &cmd, options.subdevice);
 
 	do_cmd(device,&cmd);
 
@@ -224,7 +224,7 @@ void do_cmd(comedi_t *dev,comedi_cmd *cmd)
 				go = 0;
 			}else{
 				//int i;
-	
+
 				total+=ret;
 				//printf("read %d %d\n",ret,total);
 				//printf("count = %d\n",count);
@@ -245,12 +245,12 @@ void do_cmd(comedi_t *dev,comedi_cmd *cmd)
  * of scans measured is 10.  This is analogous to the old mode2
  * acquisition.
  */
-void prepare_cmd(comedi_t *dev,comedi_cmd *cmd)
+void prepare_cmd(comedi_t *dev, comedi_cmd *cmd, int subdevice)
 {
 	memset(cmd,0,sizeof(*cmd));
 
 	/* the subdevice that the command is sent to */
-	cmd->subdev =		subdevice;
+	cmd->subdev = subdevice;
 
 	/* flags */
 	cmd->flags =		TRIG_WAKE_EOS;
diff --git a/demo/mmap.c b/demo/mmap.c
index 526aa3a..ca3534f 100644
--- a/demo/mmap.c
+++ b/demo/mmap.c
@@ -30,8 +30,8 @@ unsigned int chanlist[256];
 
 void *map;
 
-int prepare_cmd_lib(comedi_t *dev,int subdevice,comedi_cmd *cmd);
-int prepare_cmd(comedi_t *dev,int subdevice,comedi_cmd *cmd);
+int prepare_cmd_lib(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd);
+int prepare_cmd(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd);
 
 
 int main(int argc, char *argv[])
@@ -42,45 +42,47 @@ int main(int argc, char *argv[])
 	int front, back;
 	int ret;
 	int i;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	dev = comedi_open(filename);
+	dev = comedi_open(options.filename);
 	if(!dev){
-		comedi_perror(filename);
+		comedi_perror(options.filename);
 		exit(1);
 	}
 
-	size = comedi_get_buffer_size(dev,subdevice);
-	fprintf(stderr,"buffer size is %d\n",size);
+	size = comedi_get_buffer_size(dev, options.subdevice);
+	fprintf(stderr,"buffer size is %d\n", size);
 
-	map=mmap(NULL,size,PROT_READ,MAP_SHARED,comedi_fileno(dev),0);
-	fprintf(stderr,"map=%p\n",map);
+	map = mmap(NULL,size,PROT_READ,MAP_SHARED, comedi_fileno(dev), 0);
+	fprintf(stderr, "map=%p\n", map);
 	if( map == MAP_FAILED ){
 		perror( "mmap" );
 		exit(1);
 	}
 
-	for(i=0;i<n_chan;i++){
-		chanlist[i]=CR_PACK(channel+i,range,aref);
+	for(i = 0; i < options.n_chan; i++){
+		chanlist[i] = CR_PACK(options.channel + i, options.range, options.aref);
 	}
 
-	//prepare_cmd_lib(dev,subdevice,cmd);
-	prepare_cmd(dev,subdevice,cmd);
-	
-	ret = comedi_command_test(dev,cmd);
+	//prepare_cmd_lib(dev, options.subdevice, options.n_scan, options.n_chan, 1e9 / options.freq, cmd);
+	prepare_cmd(dev, options.subdevice, options.n_scan, options.n_chan, 1e9 / options.freq, cmd);
 
-	ret = comedi_command_test(dev,cmd);
+	ret = comedi_command_test(dev, cmd);
 
-	if(ret!=0){
+	ret = comedi_command_test(dev, cmd);
+
+	if(ret != 0){
 		fprintf(stderr,"command_test failed\n");
 		exit(1);
 	}
 
-	dump_cmd(stderr,cmd);
+	dump_cmd(stderr, cmd);
 
-	ret = comedi_command(dev,cmd);
-	if(ret<0){
+	ret = comedi_command(dev, cmd);
+	if(ret < 0){
 		comedi_perror("comedi_command");
 		exit(1);
 	}
@@ -88,27 +90,27 @@ int main(int argc, char *argv[])
 	front = 0;
 	back = 0;
 	while(1){
-		front += comedi_get_buffer_contents(dev,subdevice);
-		if(verbose)fprintf(stderr,"front = %d, back = %d\n",front,back);
-		if(front<back)break;
-		if(front==back){
-			//comedi_poll(dev,subdevice);
+		front += comedi_get_buffer_contents(dev, options.subdevice);
+		if(options.verbose) fprintf(stderr, "front = %d, back = %d\n", front, back);
+		if(front < back) break;
+		if(front == back){
+			//comedi_poll(dev, options.subdevice);
 			usleep(10000);
 			continue;
 		}
 
-		for(i=back;i<front;i+=sizeof(sampl_t)){
+		for(i = back; i < front; i += sizeof(sampl_t)){
 			static int col = 0;
-			printf("%d ",*(sampl_t *)(map+(i%size)));
+			printf("%d ",*(sampl_t *)(map + (i % size)));
 			col++;
-			if(col==n_chan){
+			if(col == options.n_chan){
 				printf("\n");
-				col=0;
+				col = 0;
 			}
 		}
 
-		ret = comedi_mark_buffer_read(dev,subdevice,front-back);
-		if(ret<0){
+		ret = comedi_mark_buffer_read(dev, options.subdevice, front - back);
+		if(ret < 0){
 			comedi_perror("comedi_mark_buffer_read");
 			break;
 		}
@@ -118,11 +120,11 @@ int main(int argc, char *argv[])
 	return 0;
 }
 
-int prepare_cmd_lib(comedi_t *dev,int subdevice,comedi_cmd *cmd)
+int prepare_cmd_lib(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd)
 {
 	int ret;
 
-	ret = comedi_get_cmd_generic_timed(dev,subdevice,cmd,1e9/freq);
+	ret = comedi_get_cmd_generic_timed(dev, subdevice, cmd, period_nanosec);
 	if(ret<0){
 		comedi_perror("comedi_get_cmd_generic_timed\n");
 		return ret;
@@ -132,12 +134,12 @@ int prepare_cmd_lib(comedi_t *dev,int subdevice,comedi_cmd *cmd)
 	cmd->chanlist_len = n_chan;
 	cmd->scan_end_arg = n_chan;
 
-	if(cmd->stop_src==TRIG_COUNT)cmd->stop_arg = n_scan;
+	if(cmd->stop_src == TRIG_COUNT) cmd->stop_arg = n_scan;
 
 	return 0;
 }
 
-int prepare_cmd(comedi_t *dev,int subdevice,comedi_cmd *cmd)
+int prepare_cmd(comedi_t *dev, int subdevice, int n_scan, int n_chan, unsigned period_nanosec, comedi_cmd *cmd)
 {
 	memset(cmd,0,sizeof(*cmd));
 
@@ -149,7 +151,7 @@ int prepare_cmd(comedi_t *dev,int subdevice,comedi_cmd *cmd)
 	cmd->start_arg = 0;
 
 	cmd->scan_begin_src = TRIG_TIMER;
-	cmd->scan_begin_arg = 1e9/freq;
+	cmd->scan_begin_arg = period_nanosec;
 
 	cmd->convert_src = TRIG_TIMER;
 	cmd->convert_arg = 1;
diff --git a/demo/outp.c b/demo/outp.c
index b123eee..e0b3dfd 100644
--- a/demo/outp.c
+++ b/demo/outp.c
@@ -29,28 +29,30 @@ int main(int argc, char *argv[])
 {
 	lsampl_t data;
 	int ret;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	data = value; 
-	if(verbose){
+	data = options.value;
+	if(options.verbose){
 		printf("writing %d to device=%s subdevice=%d channel=%d range=%d analog reference=%d\n",
-			data,filename,subdevice,channel,range,aref);
+			data, options.filename, options.subdevice, options.channel, options.range, options.aref);
 	}
 
-	ret=comedi_data_write(device,subdevice,channel,range,aref,data);
-	if(ret<0){
-		comedi_perror(filename);
-		exit(0);
+	ret = comedi_data_write(device, options.subdevice, options.channel, options.range, options.aref, data);
+	if(ret < 0){
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	printf("%d\n",data);
+	printf("%d\n", data);
 
 	return 0;
 }
diff --git a/demo/poll.c b/demo/poll.c
index 78c2bd3..d678b19 100644
--- a/demo/poll.c
+++ b/demo/poll.c
@@ -33,45 +33,40 @@
 #define BUFSZ 1000
 sampl_t buf[BUFSZ];
 
-int n_chans = 1;
-int n_scans = 10;
+const int n_chans = 1;
+const int n_scans = 10;
 
 unsigned int chanlist[4];
 
 comedi_t *device;
 
-void prepare_cmd(comedi_t *dev,comedi_cmd *cmd);
+void prepare_cmd(comedi_t *dev, comedi_cmd *cmd, int subdevice);
 void do_cmd(comedi_t *dev,comedi_cmd *cmd);
 
-#define sec_to_nsec(x) ((x)*1000000000)
-#define sec_to_usec(x) ((x)*1000000)
-#define sec_to_msec(x) ((x)*1000)
-#define msec_to_nsec(x) ((x)*1000000)
-#define msec_to_usec(x) ((x)*1000)
-#define usec_to_nsec(x) ((x)*1000)
-
 int main(int argc, char *argv[])
 {
 	comedi_cmd cmd;
 	int i;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device = comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		perror(filename);
+		perror(options.filename);
 		exit(1);
 	}
 
-	fcntl(comedi_fileno(device),F_SETFL,O_NONBLOCK);
+	fcntl(comedi_fileno(device), F_SETFL, O_NONBLOCK);
 
-	for(i=0;i<n_chans;i++){
-		chanlist[i]=CR_PACK(channel+i,range,aref);
+	for(i = 0; i < n_chans; i++){
+		chanlist[i] = CR_PACK(options.channel + i, options.range, options.aref);
 	}
 
-	prepare_cmd(device,&cmd);
+	prepare_cmd(device, &cmd, options.subdevice);
 
-	do_cmd(device,&cmd);
+	do_cmd(device, &cmd);
 
 	return 0;
 }
@@ -163,7 +158,7 @@ void do_cmd(comedi_t *dev,comedi_cmd *cmd)
  * of scans measured is 10.  This is analogous to the old mode2
  * acquisition.
  */
-void prepare_cmd(comedi_t *dev,comedi_cmd *cmd)
+void prepare_cmd(comedi_t *dev, comedi_cmd *cmd, int subdevice)
 {
 	memset(cmd,0,sizeof(*cmd));
 
@@ -179,7 +174,7 @@ void prepare_cmd(comedi_t *dev,comedi_cmd *cmd)
 	   src=TRIG_EXT and arg=3. */
 
 	/* In this case, we specify using TRIG_NOW to start
-	 * acquisition immediately when the command is issued.  
+	 * acquisition immediately when the command is issued.
 	 * The argument of TRIG_NOW is "number of nsec after
 	 * NOW", but no driver supports it yet.  Also, no driver
 	 * currently supports using a start_src other than
diff --git a/demo/receiver.c b/demo/receiver.c
index be71a86..7c5417a 100644
--- a/demo/receiver.c
+++ b/demo/receiver.c
@@ -37,36 +37,33 @@ comedi_t *device;
 #define BUFSZ 1024
 sampl_t buf[BUFSZ];
 
-void prepare_cmd(comedi_t *dev,comedi_cmd *cmd);
+void prepare_cmd(comedi_t *dev, comedi_cmd *cmd, int subdevice);
 void do_cmd(comedi_t *dev,comedi_cmd *cmd);
 
 int main(int argc, char *argv[])
 {
-	char *fn = NULL;
 	comedi_t *dev;
 	comedi_cmd cmd;
 	int ret;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	options.channel = -1;
+	parse_options(&options, argc, argv);
 
-	//fn = "/dev/comedi1";
-	fn = "/dev/comedi0";
-
-	dev = comedi_open(fn);
+	dev = comedi_open(options.filename);
 	if(!dev){
-		perror(fn);
+		perror(options.filename);
 		exit(1);
 	}
 	device = dev;
 
-	subdevice = 0;
-
-	if(channel)pin_data=channel;
+	if(options.channel >= 0) pin_data = options.channel;
 
 	ret = fcntl(comedi_fileno(dev),F_SETFL,O_NONBLOCK);
 	if(ret<0)perror("fcntl");
 
-	prepare_cmd(dev,&cmd);
+	prepare_cmd(dev, &cmd, options.subdevice);
 
 	do_cmd(dev,&cmd);
 
@@ -152,7 +149,7 @@ void do_cmd(comedi_t *dev,comedi_cmd *cmd)
 				go = 0;
 			}else{
 				int i;
-	
+
 				total+=ret;
 				for(i=0;i<ret/sizeof(sampl_t);i++){
 					fprintf(stderr,"%d",buf[i]>0xa000);
@@ -198,7 +195,7 @@ unsigned int chanlist[16];
  * of scans measured is 10.  This is analogous to the old mode2
  * acquisition.
  */
-void prepare_cmd(comedi_t *dev,comedi_cmd *cmd)
+void prepare_cmd(comedi_t *dev,comedi_cmd *cmd, int subdevice)
 {
 	memset(cmd,0,sizeof(comedi_cmd));
 
diff --git a/demo/select.c b/demo/select.c
index b1bfdcc..739b65b 100644
--- a/demo/select.c
+++ b/demo/select.c
@@ -33,45 +33,40 @@
 #define BUFSZ 1000
 sampl_t buf[BUFSZ];
 
-int n_chans = 1;
-int n_scans = 10;
+const int n_chans = 1;
+const int n_scans = 10;
 
 unsigned int chanlist[4];
 
 comedi_t *device;
 
-void prepare_cmd(comedi_t *dev,comedi_cmd *cmd);
+void prepare_cmd(comedi_t *dev,comedi_cmd *cmd, int subdevice);
 void do_cmd(comedi_t *dev,comedi_cmd *cmd);
 
-#define sec_to_nsec(x) ((x)*1000000000)
-#define sec_to_usec(x) ((x)*1000000)
-#define sec_to_msec(x) ((x)*1000)
-#define msec_to_nsec(x) ((x)*1000000)
-#define msec_to_usec(x) ((x)*1000)
-#define usec_to_nsec(x) ((x)*1000)
-
 int main(int argc, char *argv[])
 {
 	comedi_cmd cmd;
 	int i;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device = comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		perror(filename);
+		perror(options.filename);
 		exit(1);
 	}
 
-	fcntl(comedi_fileno(device),F_SETFL,O_NONBLOCK);
+	fcntl(comedi_fileno(device), F_SETFL, O_NONBLOCK);
 
-	for(i=0;i<n_chans;i++){
-		chanlist[i]=CR_PACK(channel+i,range,aref);
+	for(i = 0; i < n_chans; i++){
+		chanlist[i] = CR_PACK(options.channel + i, options.range, options.aref);
 	}
 
-	prepare_cmd(device,&cmd);
+	prepare_cmd(device, &cmd, options.subdevice);
 
-	do_cmd(device,&cmd);
+	do_cmd(device, &cmd);
 
 	return 0;
 }
@@ -161,7 +156,7 @@ void do_cmd(comedi_t *dev,comedi_cmd *cmd)
  * of scans measured is 10.  This is analogous to the old mode2
  * acquisition.
  */
-void prepare_cmd(comedi_t *dev,comedi_cmd *cmd)
+void prepare_cmd(comedi_t *dev, comedi_cmd *cmd, int subdevice)
 {
 	memset(cmd,0,sizeof(*cmd));
 
@@ -178,7 +173,7 @@ void prepare_cmd(comedi_t *dev,comedi_cmd *cmd)
 	   src=TRIG_EXT and arg=3. */
 
 	/* In this case, we specify using TRIG_NOW to start
-	 * acquisition immediately when the command is issued.  
+	 * acquisition immediately when the command is issued.
 	 * The argument of TRIG_NOW is "number of nsec after
 	 * NOW", but no driver supports it yet.  Also, no driver
 	 * currently supports using a start_src other than
diff --git a/demo/sender.c b/demo/sender.c
index 5207026..2c885ad 100644
--- a/demo/sender.c
+++ b/demo/sender.c
@@ -32,7 +32,7 @@ int wait2 = usec_to_nsec(0);
 
 comedi_t *device;
 
-void write_bits(int bits);
+void write_bits(int subdevice, int bits);
 
 
 int main(int argc, char *argv[])
@@ -40,31 +40,39 @@ int main(int argc, char *argv[])
 	int ret;
 	int stype;
 	int i;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	options.subdevice = -1;
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
+	}
+	if(options.subdevice < 0)
+	{
+		options.subdevice = comedi_find_subdevice_by_type(device, COMEDI_SUBD_DIO, 0);
+		if(options.subdevice < 0){
+			fprintf(stderr,"No dio subdevice found.\n");
+			exit(-1);
+		}
+	}
+	stype = comedi_get_subdevice_type(device, options.subdevice);
+	if(stype != COMEDI_SUBD_DIO){
+		printf("%d is not a digital I/O subdevice\n", options.subdevice);
+		exit(-1);
 	}
 
-	subdevice = 2;
+	printf("configuring pin %d for output...\n", chan_dat);
+	ret = comedi_dio_config(device, options.subdevice, chan_dat, COMEDI_OUTPUT);
 
-	stype = comedi_get_subdevice_type(device,subdevice);
-	if(stype!=COMEDI_SUBD_DIO){
-		printf("%d is not a digital I/O subdevice\n",subdevice);
-		exit(0);
-	}
+	printf("configuring pin %d for output...\n", chan_clk);
+	ret = comedi_dio_config(device, options.subdevice, chan_clk, COMEDI_OUTPUT);
 
-	printf("configuring pin %d for output...\n",chan_dat);
-	ret=comedi_dio_config(device,subdevice,chan_dat,COMEDI_OUTPUT);
-	
-	printf("configuring pin %d for output...\n",chan_clk);
-	ret=comedi_dio_config(device,subdevice,chan_clk,COMEDI_OUTPUT);
-	
-	for(i=0;i<0x100;i++){
-		write_bits(i);
+	for(i = 0; i < 0x100; i++){
+		write_bits(options.subdevice, i);
 	}
 	//write_bits(0xa5);
 
@@ -72,7 +80,7 @@ int main(int argc, char *argv[])
 }
 
 
-void write_bits(int bits)
+void write_bits(int subdevice, int bits)
 {
 	comedi_insnlist il;
 	comedi_insn insn[5];
diff --git a/demo/sigio.c b/demo/sigio.c
index f721d5b..d8e87f4 100644
--- a/demo/sigio.c
+++ b/demo/sigio.c
@@ -69,38 +69,35 @@ int count;
 #define BUFSZ 1024
 sampl_t buf[BUFSZ];
 
-void do_cmd_1(comedi_t *dev);
+void do_cmd_1(comedi_t *dev, int subdevice);
 void do_cmd_2(comedi_t *dev);
 void do_cmd(comedi_t *dev,comedi_cmd *cmd);
 
 int main(int argc, char *argv[])
 {
-	char *fn = NULL;
-	comedi_t *dev;
 	struct sigaction sa;
 	int ret;
 	sigset_t sigset;
 	int flags;
+	struct parsed_options options;
 
-	//fn = "/dev/comedi1";
-	fn = "/dev/comedi0";
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	dev = comedi_open(fn);
-	if(!dev){
-		perror(fn);
+	device = comedi_open(options.filename);
+	if(!device){
+		perror(options.filename);
 		exit(1);
 	}
-	device = dev;
 
-	subdevice = 0;
 	out_subd = 2;
 
 	config_output();
 
-	fcntl(comedi_fileno(dev),F_SETOWN,getpid());
-	flags = fcntl(comedi_fileno(dev),F_GETFL);
-	ret = fcntl(comedi_fileno(dev),F_SETFL,flags|O_ASYNC);
-	//ret = fcntl(comedi_fileno(dev),F_SETFL,O_NONBLOCK|O_ASYNC);
+	fcntl(comedi_fileno(device), F_SETOWN, getpid());
+	flags = fcntl(comedi_fileno(device),F_GETFL);
+	ret = fcntl(comedi_fileno(device),F_SETFL,flags|O_ASYNC);
+	//ret = fcntl(comedi_fileno(device),F_SETFL,O_NONBLOCK|O_ASYNC);
 	if(ret<0)perror("fcntl");
 
 	memset(&sa,0,sizeof(sa));
@@ -123,7 +120,7 @@ int main(int argc, char *argv[])
 	}
 #endif
 
-	do_cmd_1(dev);
+	do_cmd_1(device, options.subdevice);
 
 	return 0;
 }
@@ -196,14 +193,14 @@ unsigned int chanlist[0];
  * of scans measured is 10.  This is analogous to the old mode2
  * acquisition.
  */
-void do_cmd_1(comedi_t *dev)
+void do_cmd_1(comedi_t *dev, int subdevice)
 {
 	comedi_cmd cmd;
 
 	memset(&cmd,0,sizeof(cmd));
 
 	/* the subdevice that the command is sent to */
-	cmd.subdev =	subdevice;
+	cmd.subdev = subdevice;
 
 	/* flags */
 	cmd.flags =	TRIG_WAKE_EOS;
diff --git a/demo/sv.c b/demo/sv.c
index 41814f8..dc8e100 100644
--- a/demo/sv.c
+++ b/demo/sv.c
@@ -1,6 +1,6 @@
 /*
  * Demo of the comedi_sv_*() functions
- * 
+ *
  * Part of Comedilib
  *
  * Copyright (c) 1999,2000 David A. Schleef <ds@schleef.org>
@@ -28,33 +28,35 @@ int main(int argc, char *argv[])
 	int ret;
 	comedi_sv_t sv;
 	double volts;
+	struct parsed_options options;
 
-	parse_options(argc,argv);
+	init_parsed_options(&options);
+	parse_options(&options, argc, argv);
 
-	device=comedi_open(filename);
+	device = comedi_open(options.filename);
 	if(!device){
-		comedi_perror(filename);
-		exit(0);
+		comedi_perror(options.filename);
+		exit(-1);
 	}
 
-	if(verbose){
+	if(options.verbose){
 		printf("measuring device=%s subdevice=%d channel=%d range=%d analog reference=%d\n",
-			filename,subdevice,channel,range,aref);
+			options.filename, options.subdevice, options.channel, options.range, options.aref);
 	}
 
-	comedi_sv_init(&sv,device,subdevice,channel);
+	comedi_sv_init(&sv, device, options.subdevice, options.channel);
 
-	sv.range=range;
-	sv.aref=aref;
-	sv.n=100;
+	sv.range = options.range;
+	sv.aref = options.aref;
+	sv.n = 100;
 
-	ret=comedi_sv_measure(&sv,&volts);
-	if(ret<0){
+	ret = comedi_sv_measure(&sv, &volts);
+	if(ret < 0){
 		comedi_perror("comedi_sv_measure()");
-		exit(0);
+		exit(-1);
 	}
 
-	printf("%g\n",volts);
+	printf("%g\n", volts);
 
 	return 0;
 }