605fd55655
A struct timeval is not the same size as a pair of lsampl_t's for 64-bit, so can't point 'data' in a comedi_insn to a struct timeval and expect it to work!
116 lines
3.1 KiB
C
116 lines
3.1 KiB
C
/*
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* Instruction example
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* Part of Comedilib
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*
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* Copyright (c) 1999,2000 David A. Schleef <ds@schleef.org>
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*
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* This file may be freely modified, distributed, and combined with
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* other software, as long as proper attribution is given in the
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* source code.
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*/
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/*
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This example shows how to use instructions, i.e., comedi_insns.
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Using instructions directly, as in this example, is not recommended
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for the beginner. Use the higher-level functions such as
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comedi_data_read(), comedi_data_write(), etc., as demonstrated
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in the inp, outp, and dio examples. Then, if you need the
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additional flexibility that using instructions directly
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provides, study this example and the implementations of
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comedi_data_read(), etc.
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*/
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#include <stdio.h>
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#include <comedilib.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <sys/time.h>
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#include <unistd.h>
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#include "examples.h"
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/*
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* This example does 3 instructions in one system call. It does
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* a gettimeofday() call, then reads N_SAMPLES samples from an
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* analog input, and the another gettimeofday() call.
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*
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* (Note: The gettimeofday() value is obtained using an INSN_GTOD
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* instruction, which places the seconds value in data[0] and the
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* microseconds in data[1], so the seconds value is limited to
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* 32-bits even on 64-bit systems.)
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*/
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#define MAX_SAMPLES 128
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comedi_t *device;
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int main(int argc, char *argv[])
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{
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int ret,i;
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comedi_insn insn[3];
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comedi_insnlist il;
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lsampl_t t1[2], t2[2];
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lsampl_t data[MAX_SAMPLES];
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struct parsed_options options;
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init_parsed_options(&options);
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options.n_scan = 10; /* override default n_scan value to something more suitable */
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parse_options(&options, argc, argv);
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if(options.n_scan > MAX_SAMPLES ){
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fprintf( stderr, "Requested too many samples, reducing to %i\n", MAX_SAMPLES );
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options.n_scan = MAX_SAMPLES;
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}
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device = comedi_open(options.filename);
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if(!device){
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comedi_perror(options.filename);
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exit(-1);
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}
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if(options.verbose){
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printf("measuring device=%s subdevice=%d channel=%d range=%d analog reference=%d\n",
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options.filename, options.subdevice, options.channel, options.range, options.aref);
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}
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/* Set up a the "instruction list", which is just a pointer
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* to the array of instructions and the number of instructions.
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*/
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il.n_insns=3;
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il.insns=insn;
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/* Instruction 0: perform a gettimeofday() */
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insn[0].insn=INSN_GTOD;
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insn[0].n=2;
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insn[0].data=t1;
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/* Instruction 1: do 10 analog input reads */
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insn[1].insn=INSN_READ;
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insn[1].n = options.n_scan;
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insn[1].data=data;
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insn[1].subdev = options.subdevice;
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insn[1].chanspec=CR_PACK(options.channel, options.range, options.aref);
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/* Instruction 2: perform a gettimeofday() */
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insn[2].insn=INSN_GTOD;
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insn[2].n=2;
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insn[2].data=t2;
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ret=comedi_do_insnlist(device,&il);
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if(ret<0){
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comedi_perror(options.filename);
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exit(-1);
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}
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printf("initial time: %d.%06d\n", t1[0], t1[1]);
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for(i = 0; i < options.n_scan; i++){
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printf("%d\n", data[i]);
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}
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printf("final time: %d.%06d\n", t2[0], t2[1]);
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printf("difference (us): %ld\n",(long)(t2[0]-t1[0]) * 1000000 +
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(t2[1] - t1[1]));
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return 0;
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}
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