STORE_SECTORS is a hard requirement. If there are fewer than 2 pages
then the kvstore will not work, because the garbage collection process
relies on having at least two sectors to work with.
STORE_PAGES is a heuristic. It is a reasonable default to use if the
application does not specify the amount of flash to use for TDBStore.
But if an application knows that a smaller number of pages will suffice
for its specific needs, then that is valid and should be permitted.
When 10 pages is larger than 2 sectors, align the selected size
down to be an even multiple of the sector size, to ensure that
the allocated space divides cleanly in half for garbage collection.
The minimum size required by tdbstore is either 2 sectors or 10 pages,
whichever is larger. Correspondingly, adjust the error checks in
_calculate_blocksize_match_tdbstore to match this requirement.
Default the size to the larger of two sectors or 10 pages, so that the
computation works better on devices with a low sector to page size ratio.
Reduce code duplication.
We disable C++ static destructors as best as possible in the various
toolchains, trying to eliminate unwanted destructor code. We don't want
to waste RAM or ROM on the C++-standard-specified behaviour of running
all statically-constructed objects' destructors in reverse order on
exit; we're never going to perform an orderly exit.
Techniques used include:
* `SingletonPtr` - makes an object be "lazily constructed" on first use,
and also eliminates its destructor. Lazy construction adds ROM+RAM
overhead.
* `__eabi_atexit` is stubbed out, preventing RAM usage by run-time
registration of static destructors.
* GCC has `exit` wrapped to kill shutdown code
* IAR has static destructors disabled in the compiler flags
Killing static destructors in the compiler is the optimum; if we only
stub out `__eabi_atexit`, the compiler is still inserting calls to it,
and referencing the destructors in those call.
Clang 8 added the compiler option `-fno-c++-static-destructors` (and the
object attributes `[[clang::no_destroy]]` and
`[[clang::always_destroy]]` for fine control).
We can hence enable that option in ARMC6 tool profiles, matching IAR.
This option appears to exist in ARM Compiler 6.11, but generates an
apparently spurious linker error about `EthernetInterface`. It works in
ARM Compiler 6.13, so this PR needs to wait until the compiler is
updated.
* Add optimised constexpr default constructor. Default construction
was previously by a heavyweight defaulted `nsapi_addr_t` parameter.
* Remove deprecated resolving constructor.
* Take `nsapi_addr_t` inputs by constant reference rather than value.
* Inline the trivial getters and setters.
* Use `unique_ptr` to manage the text buffer.
* Make `operator bool` explicit.
* Optimise some methods.
* Update to C++11 style (default initialisers, nullptr etc)
phst
Martin Kojtal
Michal Paszta
Maciej Bocianski
Kyle Kearney
petroborys
jeromecoutant
Kevin Bracey
Kimmo Vaisanen
Marcin Tomczyk
Chun-Chieh Li
Dustin Crossman
Volodymyr Medvid
adbridge
Lingkai Dong