7832738ae9
Add a k_timeout_t type, and use it everywhere that kernel API functions were accepting a millisecond timeout argument. Instead of forcing milliseconds everywhere (which are often not integrally representable as system ticks), do the conversion to ticks at the point where the timeout is created. This avoids an extra unit conversion in some application code, and allows us to express the timeout in units other than milliseconds to achieve greater precision. The existing K_MSEC() et. al. macros now return initializers for a k_timeout_t. The K_NO_WAIT and K_FOREVER constants have now become k_timeout_t values, which means they cannot be operated on as integers. Applications which have their own APIs that need to inspect these vs. user-provided timeouts can now use a K_TIMEOUT_EQ() predicate to test for equality. Timer drivers, which receive an integer tick count in ther z_clock_set_timeout() functions, now use the integer-valued K_TICKS_FOREVER constant instead of K_FOREVER. For the initial release, to preserve source compatibility, a CONFIG_LEGACY_TIMEOUT_API kconfig is provided. When true, the k_timeout_t will remain a compatible 32 bit value that will work with any legacy Zephyr application. Some subsystems present timeout (or timeout-like) values to their own users as APIs that would re-use the kernel's own constants and conventions. These will require some minor design work to adapt to the new scheme (in most cases just using k_timeout_t directly in their own API), and they have not been changed in this patch, instead selecting CONFIG_LEGACY_TIMEOUT_API via kconfig. These subsystems include: CAN Bus, the Microbit display driver, I2S, LoRa modem drivers, the UART Async API, Video hardware drivers, the console subsystem, and the network buffer abstraction. k_sleep() now takes a k_timeout_t argument, with a k_msleep() variant provided that works identically to the original API. Most of the changes here are just type/configuration management and documentation, but there are logic changes in mempool, where a loop that used a timeout numerically has been reworked using a new z_timeout_end_calc() predicate. Also in queue.c, a (when POLL was enabled) a similar loop was needlessly used to try to retry the k_poll() call after a spurious failure. But k_poll() does not fail spuriously, so the loop was removed. Signed-off-by: Andy Ross <andrew.j.ross@intel.com> |
||
|---|---|---|
| .. | ||
| src | ||
| CMakeLists.txt | ||
| README.txt | ||
| prj.conf | ||
| sample.yaml | ||
README.txt
Title: C++ Synchronization
Description:
The sample project illustrates usage of pure virtual class, member
functions with different types of arguments, global objects constructor
invocation.
A simple application demonstrates basic sanity of the kernel. The main thread
and a cooperative thread take turns printing a greeting message to the console,
and use timers and semaphores to control the rate at which messages are
generated. This demonstrates that kernel scheduling, communication, and
timing are operating correctly.
--------------------------------------------------------------------------------
Building and Running Project:
This kernel project outputs to the console. It can be built and executed
on QEMU as follows:
make run
--------------------------------------------------------------------------------
Troubleshooting:
Problems caused by out-dated project information can be addressed by
issuing one of the following commands then rebuilding the project:
make clean # discard results of previous builds
# but keep existing configuration info
or
make pristine # discard results of previous builds
# and restore pre-defined configuration info
--------------------------------------------------------------------------------
Sample Output:
Create semaphore 0x001042b0
Create semaphore 0x001042c4
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
coop_thread_entry: Hello World!
main: Hello World!
<repeats endlessly>