The generic code in mbed_ticker_api.c uses run-time polymorphism to
handle different tickers, and has generic run-time calculations for
different ticker widths and frequencies, with a single special-case for
1MHz.
Extend the run-time special casing to handle any conversion cases where
either the multiply or divide can be done as a shift. This is a speed
optimisation for certain platforms.
Add a new option `target.custom-tickers`. If turned off, it promises
that only USTICKER and LPTICKER devices will be used. This then permits
elimination and/or simplification of runtime calculations, saving size
and speed. If either both USTICKER and LPTICKER have the same width, or
same period numerator or denominator, or only one of them exists, then
operations can be hard-coded. This is a significant ROM space saving,
and a minor speed and RAM saving.
We get to optimise all the calculations, but the run-time polymorphism
is retained even if there is only one ticker, as it doesn't
significantly affect code size versus direct calls, and the existence of
lp_ticker_wrapper and various us_ticker optimisations requires it, even
if only LPTICKER is available.
Some internal flashes have non-uniform sectors, and for those
ones we want to skip the initialization of default LittleFileSystem
on FlashIAPBlockDevice (unless the user specifies an address
range that's uniform).
This commit adds a config to indicate if sectors are uniform.
Workaround a bug where the boot stack size configuration option is not
passed on to armlink, the Arm Compiler's linker. Prefer
MBED_CONF_TARGET_BOOT_STACK_SIZE if present, as this is what the
configuration system should provide. Fall back to MBED_BOOT_STACK_SIZE
if MBED_CONF_TARGET_BOOT_STACK_SIZE is not defined, as in the case of
buggy tools. If both MBED_CONF_TARGET_BOOT_STACK_SIZE and
MBED_BOOT_STACK_SIZE are not defined, then we fall back to a hard-coded
value provided by the linkerscript. See
https://github.com/ARMmbed/mbed-os/issues/13474 for more information.
To allow overriding of the boot stack size from the Mbed configuration
system, consistently use MBED_CONF_TARGET_BOOT_STACK_SIZE rather than
MBED_BOOT_STACK_SIZE.
Fixes#10319
Kevin Bracey
Antti Kauppila
Teemu Takaluoma
Balaji Subramanyam
Anna Bridge
Rajkumar Kanagaraj
Lingkai Dong
Moshe Shahar
Martin Kojtal
Bora Özgen
Paul Szczeanek
Mark Horvath
Gabor Toth
jeromecoutant
Qinghao Shi
Jaeden Amero
Hugues Kamba
Wenn0101
Mark Lamb