From d4b04cd828acdb6c5ca92706088277b50cc7aa5b Mon Sep 17 00:00:00 2001
From: David Schleef <ds@schleef.org>
Date: Mon, 28 May 2001 02:33:03 +0000
Subject: [PATCH] added poll example

---
 demo/Makefile |   2 +-
 demo/poll.c   | 233 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 234 insertions(+), 1 deletion(-)
 create mode 100644 demo/poll.c

diff --git a/demo/Makefile b/demo/Makefile
index f2fcfc3..e51ba5b 100644
--- a/demo/Makefile
+++ b/demo/Makefile
@@ -8,7 +8,7 @@ LDFLAGS = -L../lib/ -lcomedi -lm
 
 BINS=tut1 tut2
 MBINS=inp inpn sv eeprom_dump info outp insn antialias ao_waveform \
-	dio mmap ledclock receiver sigio select sender cmd
+	dio mmap ledclock receiver sigio select sender cmd poll
 
 all: $(BINS) $(MBINS)
 
diff --git a/demo/poll.c b/demo/poll.c
new file mode 100644
index 0000000..3ee5a0b
--- /dev/null
+++ b/demo/poll.c
@@ -0,0 +1,233 @@
+/*
+ * poll.c - Example of using comedi_poll() with Comedi
+ * Part of Comedilib
+ *
+ * Copyright (c) 1999,2000 David A. Schleef <ds@schleef.org>
+ *
+ * This file may be freely modified, distributed, and combined with
+ * other software, as long as proper attribution is given in the
+ * source code.
+ */
+
+/*
+ * An example for using comedi_poll() in asynchronous input,
+ * so you can ask the driver to pull samples that may be waiting
+ * on the board into the buffer (so they can be read).
+ */
+
+#include <stdio.h>
+#include <comedilib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <getopt.h>
+#include <ctype.h>
+#include <string.h>
+#include <sys/time.h>
+#include "examples.h"
+
+#define N_SCANS		10
+#define N_CHANS		16
+
+double freq = 1000;
+
+#define BUFSZ 1000
+sampl_t buf[BUFSZ];
+
+int n_chans = 1;
+int n_scans = 10;
+
+unsigned int chanlist[4];
+
+comedi_t *device;
+
+void prepare_cmd(comedi_t *dev,comedi_cmd *cmd);
+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 comedi_poll(comedi_t *dev,unsigned int subdev)
+{
+	return ioctl(comedi_fileno(dev),COMEDI_POLL,subdev);
+}
+
+int main(int argc, char *argv[])
+{
+	comedi_cmd cmd;
+	int i;
+
+	parse_options(argc,argv);
+
+	device = comedi_open(filename);
+	if(!device){
+		perror(filename);
+		exit(1);
+	}
+
+	fcntl(comedi_fileno(device),F_SETFL,O_NONBLOCK);
+
+	for(i=0;i<n_chans;i++){
+		chanlist[i]=CR_PACK(channel+i,range,aref);
+	}
+
+	prepare_cmd(device,&cmd);
+
+	do_cmd(device,&cmd);
+
+	return 0;
+}
+
+void do_cmd(comedi_t *dev,comedi_cmd *cmd)
+{
+	int total=0;
+	int ret;
+	int go;
+	fd_set rdset;
+	struct timeval timeout;
+
+	ret=comedi_command_test(dev,cmd);
+
+	printf("test ret=%d\n",ret);
+	if(ret<0){
+		printf("errno=%d\n",errno);
+		comedi_perror("comedi_command_test");
+		return;
+	}
+
+	dump_cmd(cmd);
+
+	ret=comedi_command_test(dev,cmd);
+
+	printf("test ret=%d\n",ret);
+	if(ret<0){
+		printf("errno=%d\n",errno);
+		comedi_perror("comedi_command_test");
+		return;
+	}
+
+	dump_cmd(cmd);
+
+	ret=comedi_command(dev,cmd);
+
+	printf("ret=%d\n",ret);
+	if(ret<0){
+		printf("errno=%d\n",errno);
+		comedi_perror("comedi_command");
+		return;
+	}
+
+	go=1;
+	while(go){
+		FD_ZERO(&rdset);
+		FD_SET(comedi_fileno(device),&rdset);
+		timeout.tv_sec = 0;
+		timeout.tv_usec = 50000;
+		ret = select(comedi_fileno(dev)+1,&rdset,NULL,NULL,&timeout);
+		//printf("select returned %d\n",ret);
+		if(ret<0){
+			perror("select");
+		}else if(ret==0){
+			/* hit timeout */
+			printf("timeout, polling...\n");
+			ret = comedi_poll(device,0);
+			printf("poll returned %d\n",ret);
+		}else if(FD_ISSET(comedi_fileno(device),&rdset)){
+			/* comedi file descriptor became ready */
+			//printf("comedi file descriptor ready\n");
+			ret=read(comedi_fileno(dev),buf,sizeof(buf));
+			printf("read returned %d\n",ret);
+			if(ret<0){
+				if(errno==EAGAIN){
+					go = 0;
+					perror("read");
+				}
+			}else if(ret==0){
+				go = 0;
+			}else{
+				int i;
+				total+=ret;
+				//printf("read %d %d\n",ret,total);
+				for(i=0;i<ret/sizeof(sampl_t);i++){
+					printf("%d\n",buf[i]);
+				}
+			}
+		}else{
+			/* unknown file descriptor became ready */
+			printf("unknown file descriptor ready\n");
+		}
+	}
+}
+
+/*
+ * This part of the demo measures channels 1, 2, 3, 4 at a rate of
+ * 10 khz, with the inter-sample time at 10 us (100 khz).  The number
+ * of scans measured is 10.  This is analogous to the old mode2
+ * acquisition.
+ */
+void prepare_cmd(comedi_t *dev,comedi_cmd *cmd)
+{
+	memset(cmd,0,sizeof(*cmd));
+
+	/* the subdevice that the command is sent to */
+	cmd->subdev =	subdevice;
+
+	/* flags */
+	cmd->flags =	0;
+
+	/* each event requires a trigger, which is specified
+	   by a source and an argument.  For example, to specify
+	   an external digital line 3 as a source, you would use
+	   src=TRIG_EXT and arg=3. */
+
+	/* In this case, we specify using TRIG_NOW to start
+	 * 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
+	 * TRIG_NOW.  */
+	cmd->start_src =		TRIG_NOW;
+	cmd->start_arg =		0;
+
+	/* The timing of the beginning of each scan is controlled
+	 * by scan_begin.  TRIG_TIMER specifies that scan_start
+	 * events occur periodically at a rate of scan_begin_arg
+	 * nanoseconds between scans. */
+	cmd->scan_begin_src =	TRIG_TIMER;
+	cmd->scan_begin_arg =	msec_to_nsec(100);
+
+	/* The timing between each sample in a scan is controlled
+	 * by convert.  Like above, TRIG_TIMER specifies that
+	 * convert events occur periodically at a rate of convert_arg
+	 * nanoseconds between scans. */
+	cmd->convert_src =	TRIG_TIMER;
+	cmd->convert_arg =	msec_to_nsec(1);
+
+	/* The end of each scan is almost always specified using
+	 * TRIG_COUNT, with the argument being the same as the
+	 * number of channels in the chanlist.  You could probably
+	 * find a device that allows something else, but it would
+	 * be strange. */
+	cmd->scan_end_src =	TRIG_COUNT;
+	cmd->scan_end_arg =	n_chans;	/* number of channels */
+
+	/* The end of acquisition is controlled by stop_src and
+	 * stop_arg.  The src will typically be TRIG_COUNT or
+	 * TRIG_NONE.  Specifying TRIG_COUNT will stop acquisition
+	 * after stop_arg number of scans, or TRIG_NONE will
+	 * cause acquisition to continue until stopped using
+	 * comedi_cancel(). */
+	cmd->stop_src =		TRIG_COUNT;
+	cmd->stop_arg =		n_scans;
+
+	/* the channel list determined which channels are sampled.
+	   In general, chanlist_len is the same as scan_end_arg.  Most
+	   boards require this.  */
+	cmd->chanlist =		chanlist;
+	cmd->chanlist_len =	n_chans;
+}
+
-- 
2.26.2