Provide partial RTOS API for bare metal builds - things that
can be done in a single threaded environment.
Allows more code to work in both RTOS and bare metal builds without
change, and in particular gives easy access to the ability to
efficiently wait for something occurring in interrupt.
Available in bare-metal:
* ThisThread
* osThreadFlagsSet to set flags on main thread (can be set from IRQ)
* EventFlags (can be set from IRQ)
* Semaphores (can be released from IRQ)
* Mutex (dummy implementation)
Not useful:
* ConditionVariable (could only be signalled from 2nd thread)
* RtosTimer (calls in a second thread context)
* Thread
Unimplemented:
* Mail, Queue, MemoryPool
Possible future work:
* ConditionVariableCS to act as IRQ signalled ConditionVariable
Deprecate wait() in favour of acquire(), try_acquire(),
try_acquire_for() and try_acquire_until().
Brings Semaphore more into line with CMSIS-RTOS 2 (which uses "acquire"),
itself (as it has "release"), and other classes having "try", "try for"
and "try until".
Also steps away from vague "wait" term - the primary operation here is
to acquire the semaphore, and this will of course sleep.
Matches rest of RTOS class timeout parameters by using the unit name. Remove ambigious statement in reference to 0 ms being no-timeout as a timeout of 0 causes the function to not block and return immediately (osWaitForever is used as no timeout as it will wait forever)
Given the 64-bit timebase, add wait_until to Semaphore.
Naming is based on Thread::wait_until.
pthreads uses "timedwait", but that's not a good fit against our
existing wait() - pthreads only has an absolute-time wait, not relative.
Various RTOS classes were storing their CMSIS-RTOS creation attribute
structure as a member, when it's not required after construction. Reduce
memory by eliminating this member.
Kevin Bracey
kegilbert
Martin Kojtal
Amanda Butler
Bartek Szatkowski
Martin Kojtal
Senthil Ramakrishnan
Vincent Coubard
Jimmy Brisson
Christopher Haster