- `gpio_ll_toggle()` now is race-free
- avoid using a look up table but branch to the two different registers
in the `gpio_ll*()` functions
- in most cases the GPIO port is a compile time constant and the
dead branch is eliminated by the optimizer, making this vastly
more efficient
- some MCUs do only have a single port, in which case
`GPIO_PORT_NUM(port)` is known to return `0` even if `port` is
not known, resulting in one of the branch being eliminated as
dead branch no matter what
- in case it really is unknown at compile time which port to work
on, the branch can still be implemented efficiently by the
compiler e.g. using a conditional move; likely more efficient
than fetching a value from the look up table.
This commit optimizes the `gpio_conf_t` type in the following
regards:
- The "base" `gpio_conf_t` is stripped from members that only some
platforms support, e.g. drive strength, slew rate, and disabling of
the Schmitt Trigger are no longer universally available but
platform-specific extensions
- The `gpio_conf_t` is now crammed into a bit-field that is 8 bit or
16 bit wide. This allows for storing lots of them e.g. in
`driver_foo_params_t` or `uart_conf_t` etc.
- A `union` of the `struct` with bit-field members and a `bits` is used
to allow accessing all bits in a simple C statement and to ensure
alignment for efficient handling of the type
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
