The `clz` instruction pretty much implements getting the most significant bit
in hardware, so use it instead of the software implementation.
This reults in both a reduction in code size as in a speedup:
master:
text data bss dec hex filename
14816 136 2424 17376 43e0 tests/bitarithm_timings/bin/same54-xpro/tests_bitarithm_timings.elf
+ bitarithm_msb: 3529411 iterations per second
this patch:
text data bss dec hex filename
14768 136 2424 17328 43b0 tests/bitarithm_timings/bin/same54-xpro/tests_bitarithm_timings.elf
+ bitarithm_msb: 9230761 iterations per second
Big endian buffers on big endian systems are already in big endian byte order,
so no byte shuffling is needed. However, byte buffers might be unaligned, so
copy operations that are safe with unaligned memory accesses need to be
used.
It can be desirable to not have the boot message printed each time
(e.g. logs are transferred over a wireless link on battery) while
still retaining the ability to receive INFO level logs.
This adds the option to disable the boot-up message (and also to customize
it if that is desireable).
An interrupt serviced during the idle sleep can re-request a context
switch while the scheduler is already going to switch contexts after the
idle sleep. Thi sched_context_switch_request should thus be cleared
after the idle sleep and not before where it could be modified during
the idle sleep and get out of sync.
In the case that the no_thread_idle feature is active, the
runqueue_bitcache is checked twice in the case no thread is available to
schedule. This changes the inner while loop to a do-while loop to save
one check from the initial loop iteration, saving a cycle or so in the
idle case.
If a board was flashed via USB bootloader, a crash means the user has to
perform a procedure to manually enter the bootloader again for recovery.
To allow for easier recovery, automatically lauch the bootloader on crash
if `DEVELHELP` is enabled.
Those macros are all about convenience. However, always using 64 bit makes casts
nececcary that goes against the idea of having a convenience macro.
E.g. when printing a frequency in KHZ one might want to do
printf("freq: %lu kHz\n", freq / KHZ(1));
leads to an error
> error: format '%lu' expects argument of type 'long unsigned int', but argument 2 has type 'long long unsigned int'
Now we would have to cast - `%llu` is not available with newlib-nano and wholly
uneccecary.
Only use 64 bit artithmetic where necessary (GHZ, GiB), not for smaller units.
Receiving threads must not modify the contents of the message as this
is racy by definition.
Also make `msg_bus_post()` accept `const void*` instead of `char *`.
irq_% are not inlined by the compiler which leads to it branching
to a function that actually implement a single machine instruction.
Inlining these functions makes the call more efficient as well as
saving some bytes in ROM.
This commit removes the #error from the thread_flags header.
This #error makes the usage of
if(IS_USED(MODULE_THAT_DEPENDS_ON_THREAD_FLAGS)) pattern harder,
because the error is triggered each time the header is included.
If a module uses any thread_flags function it will fail in link time
anyway.
From the ARMv7-M ARM section B3.5.3:
Where there is an overlap between two regions, the register with
the highest region number takes priority.
We want to make sure the mpu_noexec_ram region has the lowest
priority to allow the mpu_stack_guard region to overwrite the first N
bytes of it.
This change fixes using mpu_noexec_ram and mpu_stack_guard together.
bitarithm.h is not needed for the interface of shed but may cause conflicts
due to different definitions of SETBIT and CLRBIT
common implementations are: (value, offset) xor (value, mask) bitarithm
implements the later
frac.c and nrf52/usbdev.c use bitarithm.h but where missing the include
sam0/rtt.c defined a bit using mask from bitarithm,
changed that to the soulution used in sam0/rtc.c
