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/********************************************************************
* Description: _timer.c
* timer.cc -- interval timer code. A TIMER object lets you wait
* on the expiration of a cyclic period, to the resolution of the
* system clock.
*
* Derived from a work by Fred Proctor & Will Shackleford
*
* Author:
* License: LGPL Version 2
* System: Linux
*
* Copyright (c) 2004 All rights reserved.
*
* Last change:
********************************************************************/
#include "rcs_print.hh" /* rcs_print_error */
#include <stdio.h> /* NULL */
#include <errno.h> /* errno */
#include <string.h> /* strerror() */
#include <errno.h> /* EINTR */
#include <unistd.h> /* select(), sysconf(), _SC_CLK_TCK */
#include <sys/time.h> /* struct timeval, gettimeofday(), struct
itimerval, setitimer(), ITIMER_REAL */
#include <linux/version.h>
#if defined(LINUX_VERSION_CODE) && defined(KERNEL_VERSION)
#if LINUX_VERSION_CODE > KERNEL_VERSION(2,2,0)
#include <sched.h>
#endif
#endif
#include "_timer.h"
/* number of seconds in a system clock tick */
double clk_tck()
{
return 1.0 / (double) sysconf(_SC_CLK_TCK);
}
/*
These values can be used with a debugger to prevent
or deliberately cause timeouts.
*/
int etime_disabled = 0;
double etime_disable_time = 0.0;
/* number of seconds from some epoch, to clock tick resolution */
double etime()
{
struct timeval tp;
double retval;
if (0 != gettimeofday(&tp, NULL)) {
rcs_print_error("etime: can't get time\n");
return 0.0;
}
retval = ((double) tp.tv_sec) + ((double) tp.tv_usec) / 1000000.0;
return retval;
}
int esleep_use_yield = 0;
/* sleeps # of seconds */
void esleep(double seconds_to_sleep)
{
struct timeval tval;
static double clk_tck_val = 0;
double total = seconds_to_sleep; /* total sleep asked for */
double started = etime(); /* time when called */
double left = total;
if (seconds_to_sleep <= 0.0)
return;
if (clk_tck_val <= 0) {
clk_tck_val = clk_tck();
}
do {
if (left < clk_tck_val && esleep_use_yield) {
sched_yield();
} else {
tval.tv_sec = (long) left; /* double->long truncates, ANSI */
tval.tv_usec = (long) ((left - (double) tval.tv_sec) * 1000000.0);
if (tval.tv_sec == 0 && tval.tv_usec == 0) {
tval.tv_usec = 1;
}
if (select(0, NULL, NULL, NULL, &tval) < 0) {
if (errno != EINTR) {
break;
}
}
}
left = total - etime() + started;
}
while (left > 0 && (left > clk_tck_val && esleep_use_yield));
return;
}
void print_etime()
{
printf("etime = %f\n", etime());
}
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