* Extract all poll/threadsafe_background/freertos from cyw43_arch into new abstraction async_context:
* provides support for asynchronous events (timers/IRQ notifications) to be handled in a safe context.
* now guarantees all callbacks happen on a single core.
* is reusable by multiple different libraries (stdio_usb can now be ported to this but hasn't been yet).
* supports multiple independent instances (independent instances will not block each other).
* cyw43_arch libraries cleaned up to use the new abstraction. Note each distinct cyw43_arch type is now a very thin layer that creates the right type of context and adds cyw43_driver and lwip support as appropriate.
Additionally,
* Add new pico_time and hardware_alarm APIs
* Add from_us_since_boot()
* Add alarm_pool_create_with_unused_hardware_alarm()
* Add alarm_pool_add_alarm_at_force_in_context()
* Add hardware_alarm_claim_unused()
* Add hardware_alarm_force_irq()
* Added panic_compact() and some minor comment cleanup; moved FIRST_USER_IRQ define to platform_defs.h
* Platform updates
- Add PICO_RP2040=1 to rp2040 builds
- Add new PICO_RP2040_B0/1/2_SUPPORTED macros and retailer chip specific code to use
- Add doxygen to platform.h
- Make pico.h includable from assembly (because header order is important and tricky) - split out platform_asm.h
- Switch to using PICO_RP2040_B0_SUPPORTED in board headers
* use PICO_DISABLE_SHARED_IRQ_HANDLERS exclusively as config for no shared handler support (rather than also PICO_MAX_SHARED_IRQ_HANDLERS == 0)
additionally make irq_add_shared_irq_handler() call irq_set_exclusive_handler() so that single usage of an IRQ still works
* Comment typo
Co-authored-by: Luke Wren <wren6991@gmail.com>
* Add documentation for gpio_irq_callback_t and rtc_callback_t (fixes#175)
* Hook up pico_binary_info and pico_bootsel_via_double_reset to the Doxygen index
* Add link to new Raspberry Pi Pico FAQ
* Consistently add parentheses for \sa or \see links to function-names
* Use consistent capitalisation for 'GitHub'
* Small typos and markup errors
In C, func() is a function taking an unspecified number of arguments,
vs func(void) a function taking no arguments. In C++ both forms indicate
"no arguments."
Update these headers to use the (void) form, which is correct in both
languages and avoids complaints when -Wstrict-prototypes is specified.
