Modify the implementation of CThunk so it does not execute from ram.
Instead is uses an array of functions in flash which can be allocated
as a thunk. The number of CThunks that can be used by an application
can be configured with MBED_CONF_PLATFORM_CTHUNK_COUNT_MAX.
The issue is that the process_oob check would only return immediately
if no data at all on entry, or when receiving a known OOB. Any other
line noise or unknown OOBs could lead to a timeout delay - read the
noise or unknown OOB then timeout waiting for another line of input.
This revised version modifies the parser to recheck readable after each
line end when only looking for OOBs, so it can immediate exit.
Save some ROM space by putting MBED_NORETURN attributes on error
functions and failed asserts.
mbed_error was documented as returning an error code. It never
actually could return, so documentation updated, but return type
kept.
Various fixes in preparation for making sure error calls do not return.
* Clear out handle_error's use of error_in_progress as a sort of spin
lock; this is most likely to deadlock if ever activated, and conflicts
with error's use of error_in_progress. Use a normal critical section lock.
* Make error use same mbed_halt_system helper as mbed_error.
* Make error's recursion check avoid print and proceed to halt, rather
than returning.
* Make mbed_error use error_in_progress to avoid recursion in same way
as error() does.
* Give mbed_halt_system its own recursion check in case of error in
mbed_die - give it a simple fallback.
* Make the in_progress things properly atomic, just in case.
An atomic flag primitive is sometimes wanted, and it is cumbersome to
create it from the compare-and-swap operation - cumbersome enough that
people often don't bother.
Put in a core_util_atomic_flag that follows the C11/C++11 atomic_flag
API, such that it could be mapped to it with #define later.
Don't extract filename from the stored error - print it directly.
Use "mbed_error_puts" for both error message and filename to avoid
buffer length limits.
Switch to puts also fixes the potential problem of an error message
containing a '%' upsetting the formatter - it should have been
mbed_printf_error("%s", error_msg) in the first place.