ptimer_destroy -- destroy the timer.
ptimer_granularity -- returns the approximate granularity of the timers.
- Timers measure time in milliseconds, but the timings they return
- are floating point numbers, so they can carry as much precision as
- the underlying system timer supports. For example, to measure the
- time it takes to run a loop, you can use something like:
+ Timers measure time in seconds, returning the timings as floating
+ point numbers, so they can carry as much precision as the
+ underlying system timer supports. For example, to measure the time
+ it takes to run a loop, you can use something like:
ptimer *tmr = ptimer_new ();
while (...)
... loop ...
- double msecs = ptimer_measure ();
- printf ("The loop took %.2f ms\n", msecs); */
+ double secs = ptimer_measure ();
+ printf ("The loop took %.2fs\n", secs); */
#include <config.h>
CLOCK_MONOTONIC where available, CLOCK_REALTIME otherwise. */
static int posix_clock_id;
-/* Resolution of the clock, in milliseconds. */
-static double posix_millisec_resolution;
+/* Resolution of the clock, initialized in posix_init. */
+static double posix_clock_resolution;
/* Decide which clock_id to use. */
if (clock_getres (clocks[i].id, &r) < 0)
continue; /* clock_getres doesn't work for this clock */
posix_clock_id = clocks[i].id;
- posix_millisec_resolution = r.tv_sec * 1000.0 + r.tv_nsec / 1000000.0;
- /* Guard against broken clock_getres returning nonsensical
- values. */
- if (posix_millisec_resolution == 0)
- posix_millisec_resolution = 1;
+ posix_clock_resolution = (double) r.tv_sec + r.tv_nsec / 1e9;
+ /* Guard against nonsense returned by a broken clock_getres. */
+ if (posix_clock_resolution == 0)
+ posix_clock_resolution = 1e-3;
break;
}
if (i == countof (clocks))
strerror (errno));
/* Use CLOCK_REALTIME, but invent a plausible resolution. */
posix_clock_id = CLOCK_REALTIME;
- posix_millisec_resolution = 1;
+ posix_clock_resolution = 1e-3;
}
}
static inline double
posix_diff (ptimer_system_time *pst1, ptimer_system_time *pst2)
{
- return ((pst1->tv_sec - pst2->tv_sec) * 1000.0
- + (pst1->tv_nsec - pst2->tv_nsec) / 1000000.0);
+ return ((pst1->tv_sec - pst2->tv_sec)
+ + (pst1->tv_nsec - pst2->tv_nsec) / 1e9);
}
static inline double
posix_resolution (void)
{
- return posix_millisec_resolution;
+ return posix_clock_resolution;
}
#endif /* PTIMER_POSIX */
static inline double
gettimeofday_diff (ptimer_system_time *pst1, ptimer_system_time *pst2)
{
- return ((pst1->tv_sec - pst2->tv_sec) * 1000.0
- + (pst1->tv_usec - pst2->tv_usec) / 1000.0);
+ return ((pst1->tv_sec - pst2->tv_sec)
+ + (pst1->tv_usec - pst2->tv_usec) / 1e6);
}
static inline double
static bool windows_hires_timers;
/* Frequency of high-resolution timers -- number of updates per
- millisecond. Calculated the first time ptimer_new is called
- provided that high-resolution timers are available. */
-static double windows_hires_msfreq;
+ second. Calculated the first time ptimer_new is called provided
+ that high-resolution timers are available. */
+static double windows_hires_freq;
static void
windows_init (void)
if (freq.QuadPart != 0)
{
windows_hires_timers = true;
- windows_hires_msfreq = (double) freq.QuadPart / 1000.0;
+ windows_hires_freq = (double) freq.QuadPart;
}
}
windows_diff (ptimer_system_time *pst1, ptimer_system_time *pst2)
{
if (windows_hires_timers)
- return (pst1->hires.QuadPart - pst2->hires.QuadPart) / windows_hires_msfreq;
+ return (pst1->hires.QuadPart - pst2->hires.QuadPart) / windows_hires_freq;
else
return pst1->lores - pst2->lores;
}
windows_resolution (void)
{
if (windows_hires_timers)
- return 1.0 / windows_hires_msfreq;
+ return 1.0 / windows_hires_freq;
else
return 10; /* according to MSDN */
}
time, yields elapsed time. */
ptimer_system_time start;
- /* The most recent elapsed time, calculated by ptimer_measure().
- Measured in milliseconds. */
+ /* The most recent elapsed time, calculated by ptimer_measure(). */
double elapsed_last;
/* Approximately, the time elapsed between the true start of the
}
/* Reset timer PT. This establishes the starting point from which
- ptimer_read() will return the number of elapsed milliseconds.
- It is allowed to reset a previously used timer. */
+ ptimer_measure() will return the elapsed time in seconds. It is
+ allowed to reset a previously used timer. */
void
ptimer_reset (struct ptimer *pt)
pt->elapsed_pre_start = 0;
}
-/* Measure the elapsed time since timer creation/reset and return it
- to the caller. The value remains stored for further reads by
- ptimer_read.
-
- This function causes the timer to call gettimeofday (or time(),
- etc.) to update its idea of current time. To get the elapsed
- interval in milliseconds, use ptimer_read.
+/* Measure the elapsed time since timer creation/reset. This causes
+ the timer to internally call clock_gettime (or gettimeofday, etc.)
+ to update its idea of current time. The time is returned, but is
+ also stored for later access through ptimer_read().
This function handles clock skew, i.e. time that moves backwards is
ignored. */
return elapsed;
}
-/* Return the elapsed time in milliseconds between the last call to
- ptimer_reset and the last call to ptimer_update. */
+/* Return the most recent elapsed time measured with ptimer_measure.
+ If ptimer_measure has not yet been called since the timer was
+ created or reset, this returns 0. */
double
ptimer_read (const struct ptimer *pt)
}
/* Return the assessed resolution of the timer implementation, in
- milliseconds. This is used by code that tries to substitute a
- better value for timers that have returned zero. */
+ seconds. This is used by code that tries to substitute a better
+ value for timers that have returned zero. */
double
ptimer_resolution (void)
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