async_context_freertos: Add support for configSUPPORT_STATIC_ALLOCATION #2436
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kilograham
reviewed
Apr 23, 2025
kilograham
reviewed
Apr 23, 2025
src/rp2_common/pico_async_context/include/pico/async_context_freertos.h
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I pushed a new change that does not try to fall back to |
kilograham
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May 20, 2025
kilograham
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May 29, 2025
The implementation of async_context_freertos currently assumes that FreeRTOS has been configured with `configSUPPORT_DYNAMIC_ALLOCATION`, which causes it to allocate semaphores, timers and tasks from the heap. However, some projects may prefer `configSUPPORT_STATIC_ALLOCATION`, which requires memory to be allocated ahead of time. This change allows async_context_freertos to support either static or dynamic allocation. The way this works is when `configSUPPORT_STATIC_ALLOCATION` is enabled, `async_context_freertos` struct will reserve extra space for the static objects (e.g. `StaticSemaphore_t`) and it will prefer to use the static creation functions (e.g. `xSemaphoreCreateBinaryStatic()`). For the task creation, the user will be responsible for allocating the stack memory and setting the task_stack field in `async_context_freertos_config_t`. For convenience, The `cyw43_arch_init_default_async_context()` function will reserve `CYW43_TASK_STACK_SIZE` words of stack space in static memory.
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| /** | ||
| * \brief Pointer to stack memory for the async_context task. | ||
| * If this is not provided, then a stack will be allocated from the | ||
| * freertos heap. |
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is this comment still true?
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LwIP NO_SYS=0 requires configSUPPORT_DYNAMIC_ALLOCATION so that's one use case for having both (it works fine) although I'm not sure why you'd bother? |
In theory you can use your own async context therefore bypassing cyw43_arch_init_default_async_context, which would leave cyw43_async_context_freertos_task_stack unused. Add a #define for this rare situation.
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The implementation of async_context_freertos currently assumes that FreeRTOS has been configured with
configSUPPORT_DYNAMIC_ALLOCATION, which causes it to allocate semaphores, timers and tasks from the heap. However, some projects may preferconfigSUPPORT_STATIC_ALLOCATION, which requires memory to be alloc 8000 ated ahead of time. This change allows async_context_freertos to support either static or dynamic allocation.The way this works is when
configSUPPORT_STATIC_ALLOCATIONis enabled,async_context_freertosstruct will reserve extra space for the static objects (e.g.StaticSemaphore_t) and it will prefer to use the static creation functions (e.g.xSemaphoreCreateBinaryStatic()). For the task creation, the user will be responsible for allocating the stack memory and passing it in through the config. If a stack is not provided, then it will fallback to using dynamic allocation for the stack (e.g.xTaskCreate()).