--- /dev/null
+/*
+ * 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;
+}
+
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