| .. _module-pw_chrono: |
| |
| --------- |
| pw_chrono |
| --------- |
| Pigweed's chrono module provides facilities for applications to deal with time, |
| leveraging many pieces of STL's the ``std::chrono`` library but with a focus |
| on portability for constrained embedded devices and maintaining correctness. |
| |
| At a high level Pigweed's time primitives rely on C++'s |
| `<chrono> <https://en.cppreference.com/w/cpp/header/chrono>`_ library to enable |
| users to express intents with strongly typed real time units. In addition, it |
| extends the C++ named |
| `Clock <https://en.cppreference.com/w/cpp/named_req/Clock>`_ and |
| `TrivialClock <https://en.cppreference.com/w/cpp/named_req/TrivialClock>`_ |
| requirements with additional attributes such as whether a clock is monotonic |
| (not just steady), is always enabled (or requires enabling), is free running |
| (works even if interrupts are masked), whether it is safe to use in a |
| Non-Maskable Interrupts (NMI), what the epoch is, and more. |
| |
| .. warning:: |
| This module is still under construction, the API is not yet stable. Also the |
| documentation is incomplete. |
| |
| SystemClock facade |
| ------------------ |
| The ``pw::chrono::SystemClock`` is meant to serve as the clock used for time |
| bound operations such as thread sleeping, waiting on mutexes/semaphores, etc. |
| The ``SystemClock`` always uses a signed 64 bit as the underlying type for time |
| points and durations. This means users do not have to worry about clock overflow |
| risk as long as rational durations and time points as used, i.e. within a range |
| of ±292 years. |
