Overview

The SystemClock represents an unsteady, monotonic clock.

The epoch of this clock is unspecified and may not be related to wall time (for example, it can be time since boot). The time between ticks of this clock may vary due to sleep modes and potential interrupt handling. SystemClock meets the requirements of C++'s TrivialClock and Pigweed's PigweedClock.

SystemClock is compatible with C++'s Clock & TrivialClock including:

SystemClock::rep
SystemClock::period
SystemClock::duration
SystemClock::time_point
SystemClock::is_steady
SystemClock::now()

Example:

SystemClock::time_point before = SystemClock::now();
TakesALongTime();
SystemClock::duration time_taken = SystemClock::now() - before;
bool took_way_too_long = false;
if (time_taken > std::chrono::seconds(42)) {
  took_way_too_long = true;
}

This code is thread & IRQ safe, it may be NMI safe depending on is_nmi_safe.

Public Types
using	rep = int64_t

using	period = std::ratio< PW_CHRONO_SYSTEM_CLOCK_PERIOD_SECONDS_NUMERATOR, PW_CHRONO_SYSTEM_CLOCK_PERIOD_SECONDS_DENOMINATOR >
	The period must be provided by the backend.

using	duration = std::chrono::duration< rep, period >
	Alias for durations representable with this clock.

using	time_point = std::chrono::time_point< SystemClock >

Static Public Member Functions
static time_point	now () noexcept
	This is thread and IRQ safe. This must be provided by the backend.

template<class Rep , class Period >
static constexpr duration	for_at_least (std::chrono::duration< Rep, Period > d)

static time_point	TimePointAfterAtLeast (duration after_at_least)

Static Public Attributes
static constexpr Epoch	epoch = backend::kSystemClockEpoch
	The epoch must be provided by the backend.

static constexpr bool	is_monotonic = true

static constexpr bool	is_steady = false

static constexpr bool	is_free_running = backend::kSystemClockFreeRunning

static constexpr bool	is_stopped_in_halting_debug_mode = true
	The clock must stop while in halting debug mode.

static constexpr bool	is_always_enabled = true
	The now() function can be invoked at any time.

static constexpr bool	is_nmi_safe = backend::kSystemClockNmiSafe

The documentation for this struct was generated from the following file:

pw_chrono/public/pw_chrono/system_clock.h

Overview

Public Types

Static Public Member Functions

Static Public Attributes