This provides the ability to generate really small delays - it's often
the case that wait_us() takes multiple microseconds to set up, so
having an alternative suitable for <10us delays is useful.
There have been a few local implementations - it makes sense to
centralise them as they need retuning for each new ARM core.
Based on the local implementation inside the Atmel 802.15.4 driver.
Add a necessary helper to allow FileHandle objects to be obtained
from POSIX file descriptors.
Primary envisaged use case is to act on STDIN_FILENO etc, eg to
set it non-blocking or use sigio, or to use the enable API.
Add API to dynamically enable/disable input and output on FileHandles.
Aim is to allow power saving by indicating that we permanently or
temporarily do not require input, so that for example serial Rx
interrupts can be released, and deep sleep permitted.
Memory model for RTOS and No RTOS was initially single stack and heap,
only few targets implemented 2-region RAM model.
2-region RAM model is applied for all toolchains and targets.
GCC: __wrap__sbrk was implemented for 2-region ram model, with switch to 2-region
for all targets, we do not need target specific implementation of this API
Also _sbrk is WEAK function, hence can be over written in target folder for
special cases
The following commits: #8039, #9092 added Boot/ISR stack definition to all scatter files (ARM_LIB_STACK).
This has changed memory model for RTOS-less builds to 2-region memory model and caused failure in case of rtos less builds.
This PR defines valid heap/stack regions for rtos-less builds.
Fix the following build warning
Compile [ 83.4%]: mbed_error.c
[Warning] mbed_error.c@71,21: 'compute_crc32' defined but not used [-Wunused-function]
compute_crc32 usage is guraded with #define, but not the definition.
Use the same #define around the definition of compute_crc32()
SharedPtr::reset did not actually set the stored pointer value.
Correct this, with other minor tidies:
* Ensure counter is set to NULL if pointer is reset to NULL
* Be consistent about not clearing pointers in decrement_counter().
->move() operator was not touching unused data fields, therefore
leaving uninitialised data and failing the comparison.
Fixed by initialising all fields to zero before moving.
mbed_die was calling wait_ms in a critical section - this is deprecated
behaviour, and caused a fatal error in debug builds, potentially leading
to an infinite reboot loop if this was caused due to a reboot limit
halt.
Switch to using wait_us - this is safe in a critical section. This does
trigger a call to mbed_warning, due to the large parameter, but that is
harmless - it doesn't output anything to the console, and won't
overwrite the error context if it already contains something.
The pre-main check of error_reboot_count was applied repeatedly on
every boot, meaning that once the reboot limit was hit, every subsequent
reset would halt before main, until something managed to clear
or corrupt the error context.
Set the is_error_processed flag before halting, so that when an external
agent resets us while we're halted, we do not report the error and halt
again.
A couple of places in mbed_retarget.cpp were testing for either ARMC5 or
ARMC6 in a long-winded fashion. Testing for __ARMCC_VERSION being
defined is sufficient.
Similar to SingletonPtr, use atomic accesses when loading the guard word
outside the lock, and when storing, to ensure no races for threads that
don't take the lock.
Lack of atomics unlikely to be a problem in current builds, but code
could conceivably be subject to reordering if link-time optimisation was
enabled.
SingletonPtr's implementation wasn't totally safe - see "C++ and the
Perils of Double-Checked Locking"by Meyers and Alexandrescu. No problems
observed in practice, but it was potentially susceptible to compiler
optimisation (or maybe even SMP issues).
Now that we have atomic loads and stores, the function can be made safe,
avoiding any potential races for threads that don't take the lock:
ensure that the unlocked load is atomic, and that the pointer store is
atomic.
See https://preshing.com/20130930/double-checked-locking-is-fixed-in-cpp11/
for more discussion.
As barriers were added in #9247, review comments pointed out that atomic
stores needed a second barrier, and they got one. But atomic_flag_clear
was missed.
Add atomic load and store functions, and add barriers to the existing atomic
functions.
File currently has no explicit barriers - we don't support SMP, so don't
need CPU barriers.
But we do need to worry about compiler barriers - particularly if link time
optimisation is activated so that the compiler can see inside these
functions. The assembler or intrinsics that access PRIMASK for
enter/exit critical act as barriers, but LDREX, STREX and simple
volatile pointer loads and stores do not.
Critical section count/state variables are synchronised by IRQ disabling and
critical section calls themselves, so do not need to be volatile.
This eliminates a couple of unnecessary reads of the counter variable.
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>
As part of work to improve the debugging of exceptions, have
Mbed OS make an effort to make exceptions more precise in debug builds
at the cost of performance.
Related pyOCD work:
https://github.com/mbedmicro/pyOCD/pull/430
Make the option positively named, and as it is a platform config
option make sure it only affects platform code.
HAL functions still remain available even if platform is told not
to use them.
MPU lock under- or overflow is not a likely random runtime failure - it
will be a mismatched lock/unlock programming error, so should be
detected during development. Make the checks asserts so they can be
left out from release builds. MBED_ASSERT is also a bit smaller than
MBED_ERROR in develop builds.
Make the following changes:
-Allow a vector specific ARM MPU driver by defining MBED_MPU_CUSTOM
-Allow ROM address to be configured for ARMv7-M devices by
setting the define MBED_MPU_ROM_END
-Add ROM write protection
-Add new functions and lock
-enable at boot
-disable during flash programming
Martin Kojtal
Mahesh Mahadevan
Michael Schwarcz
deepikabhavnani
Cruz Monrreal
Senthil Ramakrishnan
Jimmy Brisson
Kevin Bracey
Sarah Marsh
Przemyslaw Stekiel
Steve Cartmell
Naveen Kaje
Veijo Pesonen
Seppo Takalo
paul-szczepanek-arm
kegilbert
bcostm
Alastair D'Silva
Russ Butler
Filip Jagodzinski