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Add support for CLOCK_MONOTONIC. From Macs N

This commit is contained in:
Gregory Nutt 2014-03-31 09:25:50 -06:00
parent 6bb8cc02df
commit 8772a4e104
3 changed files with 85 additions and 24 deletions
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2
ChangeLog
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@ -7087,4 +7087,6 @@
* libc/stdio/lib_sccanf.c: Fix a counting error in the return
value from sscanf(). Noted by kfrolov. Also, sscanf() should
return EOF if no values were converted (2014-3-30).
* include/time.h and sched/clock_settime(): Add support for
CLOCK_REALTIME. From Macs N (2014-3-31).

29
include/time.h
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@ -1,7 +1,7 @@
/********************************************************************************
* include/time.h
*
* Copyright (C) 2007-2011, 2013 Gregory Nutt. All rights reserved.
* Copyright (C) 2007-2011, 2013-2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@ -67,19 +67,23 @@
# define CLOCKS_PER_SEC (100)
#endif
/* CLOCK_REALTIME refers to the standard time source. For most implementations,
* the standard time source is the system timer interrupt. However, if the
* platform supports an RTC, then the standard time source will be the RTC
* for the clock_gettime() and clock_settime() interfaces (the system timer
* is still the time source for all of the interfaces).
/* CLOCK_REALTIME refers to the standard time source. For most
* implementations, the standard time source is the system timer interrupt.
* However, if the platform supports an RTC, then the standard time source
* will be the RTC for the clock_gettime() and clock_settime() interfaces
* (the system timer is still the time source for all of the interfaces).
*
* CLOCK_REALTIME represents the machine's best-guess as to the current
* wall-clock, time-of-day time. This means that CLOCK_REALTIME can jump
* forward and backward as the system time-of-day clock is changed.
*/
#define CLOCK_REALTIME 0
/* If an RTC is supported, then the non-standard CLOCK_ACTIVETIME is also
* supported to manage time based on the system timer interrupt separately from
* the RTC. This may be necessary, for example, in certain cases where the
* system timer interrupt has been stopped in low power modes.
* supported to manage time based on the system timer interrupt separately
* from the RTC. This may be necessary, for example, in certain cases where
* the system timer interrupt has been stopped in low power modes.
*
* CLOCK_ACTIVETIME is only recognized by clock_gettime() and clock_settime().
*/
@ -90,6 +94,13 @@
# define CLOCK_ACTIVETIME CLOCK_REALTIME
#endif
/* Clock that cannot be set and represents monotonic time since some
* unspecified starting point. It is not affected by changes in the
* system time-of-day clock.
*/
#define CLOCK_MONOTONIC 2
/* This is a flag that may be passed to the timer_settime() function */
#define TIMER_ABSTIME 1

78
sched/clock_gettime.c
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@ -1,7 +1,7 @@
/************************************************************************
* sched/clock_gettime.c
*
* Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved.
* Copyright (C) 2007, 2009, 2011, 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@ -51,7 +51,7 @@
#include "clock_internal.h"
/************************************************************************
* Definitions
* Pre-processor Definitions
************************************************************************/
/************************************************************************
@ -101,35 +101,80 @@ int clock_gettime(clockid_t clock_id, struct timespec *tp)
uint32_t secs;
uint32_t nsecs;
#endif
uint32_t carry;
int ret = OK;
sdbg("clock_id=%d\n", clock_id);
DEBUGASSERT(tp != NULL);
/* CLOCK_REALTIME - POSIX demands this to be present. This is the wall
* time clock.
/* CLOCK_MONOTONIC is an optional under POSIX: "If the Monotonic Clock
* option is supported, all implementations shall support a clock_id
* of CLOCK_MONOTONIC defined in <time.h>. This clock represents the
* monotonic clock for the system. For this clock, the value returned
* by clock_gettime() represents the amount of time (in seconds and
* nanoseconds) since an unspecified point in the past (for example,
* system start-up time, or the Epoch). This point does not change
* after system start-up time. The value of the CLOCK_MONOTONIC clock
* cannot be set via clock_settime(). This function shall fail if it
* is invoked with a clock_id argument of CLOCK_MONOTONIC."
*/
if (clock_id == CLOCK_MONOTONIC)
{
/* Get the time since power-on in seconds and milliseconds */
msecs = MSEC_PER_TICK * g_system_timer;
secs = msecs / MSEC_PER_SEC;
/* Return the elapsed time in seconds and nanoseconds */
nsecs = (msecs - (secs * MSEC_PER_SEC)) * NSEC_PER_MSEC;
if (nsecs > NSEC_PER_SEC)
{
carry = nsecs / NSEC_PER_SEC;
secs += carry;
nsecs -= (carry * NSEC_PER_SEC);
}
tp->tv_sec = (time_t)secs;
tp->tv_nsec = (long)nsecs;
}
/* CLOCK_REALTIME - POSIX demands this to be present. CLOCK_REALTIME
* represents the machine's best-guess as to the current wall-clock,
* time-of-day time. This means that CLOCK_REALTIME can jump forward and
* backward as the system time-of-day clock is changed.
*
* If an RTC is supported, then the non-standard CLOCK_ACTIVETIME is also
* supported to manage time based on the system timer interrupt separately
* from the RTC. This may be necessary, for example, in certain cases where
* the system timer interrupt has been stopped in low power modes.
*/
#ifdef CONFIG_RTC
if (clock_id == CLOCK_REALTIME || clock_id == CLOCK_ACTIVETIME)
else if (clock_id == CLOCK_REALTIME || clock_id == CLOCK_ACTIVETIME)
#else
if (clock_id == CLOCK_REALTIME)
else if (clock_id == CLOCK_REALTIME)
#endif
{
/* Do we have a high-resolution RTC that can provie us with the time? */
/* Do we have a high-resolution RTC that can provide us with the time? */
#ifdef CONFIG_RTC_HIRES
if (g_rtc_enabled && clock_id != CLOCK_ACTIVETIME)
{
/* Yes.. Get the hi-resolution time from the RTC */
/* Yes.. Get the hi-resolution time from the RTC unless the caller
* has specifically asked for the system timer (CLOCK_ACTIVETIME)
*/
ret = up_rtc_gettime(tp);
}
else
#endif
{
/* Get the elapsed time since power up (in milliseconds) biased
* as appropriate.
/* Get the elapsed time since the time-of-day was last set.
* g_system_timer provides the number of clock times since
* power was applied; the bias value corresponds to the time
* when the time-of-day was last set.
*/
msecs = MSEC_PER_TICK * (g_system_timer - g_tickbias);
@ -146,7 +191,10 @@ int clock_gettime(clockid_t clock_id, struct timespec *tp)
(int)msecs, (int)g_basetime.tv_sec,
(int)nsecs, (int)g_basetime.tv_nsec);
/* Add the base time to this. */
/* Add the base time to this. The base time is the time-of-day
* setting. When added to the elapsed time since the time-of-day
* was last set, this gives us the current time.
*/
secs += (uint32_t)g_basetime.tv_sec;
nsecs += (uint32_t)g_basetime.tv_nsec;
@ -155,9 +203,9 @@ int clock_gettime(clockid_t clock_id, struct timespec *tp)
if (nsecs > NSEC_PER_SEC)
{
uint32_t dwCarrySecs = nsecs / NSEC_PER_SEC;
secs += dwCarrySecs;
nsecs -= (dwCarrySecs * NSEC_PER_SEC);
carry = nsecs / NSEC_PER_SEC;
secs += carry;
nsecs -= (carry * NSEC_PER_SEC);
}
/* And return the result to the caller. */
@ -172,7 +220,7 @@ int clock_gettime(clockid_t clock_id, struct timespec *tp)
{
sdbg("Returning ERROR\n");
errno = EINVAL;
set_errno(EINVAL);
ret = ERROR;
}