For time-based functions that work with absolute time there is the need for
an Epoch, to set the zero-point at which the absolute time starts counting.
Such functions include time.time() and filesystem stat return values. And
different ports may use a different Epoch.
To make it clearer what functions use the Epoch (whatever it may be), and
make the ports more consistent with their use of the Epoch, this commit
renames all Epoch related functions to include the word "epoch" in their
name (and remove references to "2000").
Along with this rename, the following things have changed:
- mp_hal_time_ns() is now specified to return the number of nanoseconds
since the Epoch, rather than since 1970 (but since this is an internal
function it doesn't change anything for the user).
- littlefs timestamps on the esp8266 have been fixed (they were previously
off by 30 years in nanoseconds).
Otherwise, there is no functional change made by this commit.
Signed-off-by: Damien George <damien@micropython.org>
Note: the uncrustify configuration is explicitly set to 'add' instead of
'force' in order not to alter the comments which use extra spaces after //
as a means of indenting text for clarity.
machine.Timer now takes a new argument in its constructor (or init method):
tick_hz which specified the units for the period argument. The period of
the timer in seconds is: period/tick_hz.
For backwards compatibility tick_hz defaults to 1000. If the user wants to
specify the period (numerator) in microseconds then tick_hz can be set to
1000000. The user can also specify a period of an arbitrary number of
cycles of an arbitrary frequency using these two arguments.
An additional freq argument has been added to allow frequencies to be
specified directly in Hertz. This supports floating point values when
available.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
