As the timer code became more generic, coping with initialization on
demand, and variable width and speed us_ticker_api implementations,
wait_us has gradually gotten slower and slower.
Some platforms have reportedly seen overhead of wait_us() increase from
10µs to 30µs. These changes should fully reverse that drop, and even
make it better than ever.
Add fast paths for platforms that provide compile-time information about
us_ticker. Speed and code size is improved further if:
* Timer has >= 2^32 microsecond range, or better still is 32-bit 1MHz.
* Platform implements us_ticker_read() as a macro
* Timer is initialised at boot, rather than first use
The latter initialisation option is the default for STM, as this has
always been the case.
Correct C++14 operation of the alloc wrappers requires us to define
custom sized delete operators.
Their presence won't cause any problem for people compiling as C++03 or
C++11.
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.
In rtos-less code, heap is defined by assuming one-region. Through weak-reference to
ARM_LIB_HEAP, heap definition is fixed if ARM_LIB_HEAP is defined.
Please note the heap address of the both the banks must not be contigious else
GCC considers it to be single memory bank and does allocation across the banks,
which might result into hard-fault
New `target.console-uart` option added to indicate whether a target has
a console UART on STDIO_UART_TX/RX/RTS/CTS pins. (The existing option
`target.console-uart-flow-control` indicates whether RTS and or CTS is
available in addition to TX and RX).
The option defaults to true, and is currently true on all platforms. It
only applies if DEVICE_SERIAL is true, so no need to go through and mark
it false for non-SERIAL platforms.
An application can turn off target.console-uart to save ROM/power/etc if
they don't want to use the serial console. If this is turned off, the
console won't be activated for stdin/stdout, but the application is
still free to open `UARTSerial(STDIO_UART_TX, STDIO_UART_RX)`
themselves.
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.
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.
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.
Mbed retarget does an `fflush` on stdout and stderr on exit - this
flushes the C library buffers (if it is buffering), but doesn't
flush any device buffers (eg UARTSerial's TX buffer). Add
sync() calls to the output device to do this.
You are allowed in POSIX / ANSI C to read and write on the same stream, but you
have to do an fseek in between read and write call (getc->fseek->putc)
Thanks @Alex-EEE for sharing the fix: https://github.com/ARMmbed/mbed-os/pull/7749
Added test case for verification of the behavior
Add the POSIX fcntl call, but only implementing F_SETFL and F_GETFL
for O_NONBLOCK, so users can control the blocking flag of streams
with only the integer file descriptor.
Necessary to portably control the blockingness of the console:
int flags = fcntl(STDOUT_FILENO, F_GETFL);
fcntl(STDOUT_FILENO, F_SETFL, flags | O_NONBLOCK);
Kevin Bracey
Martin Kojtal
Anna Bridge
Deepika
ccli8
Senthil Ramakrishnan
Przemyslaw Stekiel
Michael Schwarcz
kegilbert
Cruz Monrreal