The timer prescaler is buffered by default, and this patch enables ARPE
which buffers the auto-reload register. With both of these registers
buffered it's now possible to smoothly change the timer's frequency and
have a smoothly varying PWM output.
Current users of fixed vstr buffers (building file paths) assume that there
is no overflow and do not check for overflow after building the vstr. This
has the potential to lead to NULL pointer dereferences
(when vstr_null_terminated_str returns NULL because it can't allocate RAM
for the terminating byte) and stat'ing and loading invalid path names (due
to the path being truncated). The safest and simplest thing to do in these
cases is just raise an exception if a write goes beyond the end of a fixed
vstr buffer, which is what this patch does. It also simplifies the vstr
code.
Prior to this patch calling pyb.Timer(id) would always create a new timer
instance, even if there was an existing one. This patch fixes this
behaviour to match other peripherals, like UART, such that constructing a
timer with just the id will retrieve any existing instances.
The patch also refactors the way timers are validated on construction to
simplify and reduce code size.
If, for class X, X.__add__(Y) doesn't exist (or returns NotImplemented),
try Y.__radd__(X) instead.
This patch could be simpler, but requires undoing operand swap and
operation switch to get non-confusing error message in case __radd__
doesn't exist.
connect, send, recv, sendto and recvfrom now release the GIL. accept
already releases the GIL because it calls mp_hal_delay_ms() within its
busy-wait loop.
Previous to this patch the i2c.scan() method would do up to 100 probes per
I2C address, to detect the devices on the bus. This repeated probing was a
relic from when the code was copied from the accelerometer initialisation,
which requires to do repeated probes while waiting for the accelerometer
chip to turn on.
But I2C devices shouldn't need more than 1 probe to detect their presence,
and the generic software I2C implementation uses 1 probe successfully. So
this patch changes the implementation to use 1 probe per address, which
significantly speeds up the scan operation.
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.
