Reimplement atomic code in inline assembly. This can improve
optimisation, and avoids potential architectural problems with using
LDREX/STREX intrinsics.
API further extended:
* Bitwise operations (fetch_and/fetch_or/fetch_xor)
* fetch_add and fetch_sub (like incr/decr, but returning old value -
aligning with C++11)
* compare_exchange_weak
* Explicit memory order specification
* Basic freestanding template overloads for C++
This gives our existing C implementation essentially all the functionality
needed by C++11.
An actual Atomic<T> template based upon these C functions could follow.
One gets this compiler warning from nvstore.cpp:
```
Compile [ 48.6%]: nvstore.cpp
[Warning] nvstore.cpp@814,9: variable 'os_ret' set but not used [-Wunused-but-set-variable]
```
Turns out it's caused by the fact that the variable is only used
with MBED_ASSERTs, which get optimized out or not, depending on your
build profile. In reality we do not need a separate variable for that
in my opinion though, so we can just use the ret-variable instead
and drop the os_ret variable completely and thus avoid this
compiler warning.
Few boards may fail the write actions due to HW limitations (like critical
drivers that disable flash operations). Just retry a few times until success.
In addition, remove the redundant retries in NVStore (not needed now).
Don't allocate the sector map array in this function,
as it was buggy and redundant. Separate user config vs. automatic allocation
cases instead (which was essentially the case anyway).
In addition, fix tests to get over failures in low end boards
The DEVICE_FOO macros are always defined (either 0 or 1).
This patch replaces any instances of a define check on a DEVICE_FOO
macro with value test instead.
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Seppo Takalo
Michal Paszta
Marcin Tomczyk
Kevin Bracey
Martin Kojtal
Janne Kiiskila
Cruz Monrreal
David Saada
Yossi Levy
Alastair D'Silva
Amir Cohen