kopia lustrzana https://github.com/espressif/esp-idf
60 wiersze
2.1 KiB
ReStructuredText
60 wiersze
2.1 KiB
ReStructuredText
Call function with external stack
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=================================
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Overview
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--------
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A given function can be executed with a user allocated stack space which is independent of current task stack, this mechanism can be used to save stack space wasted by tasks which call a common function with intensive stack usage such as `printf`. The given function can be called inside the shared stack space which is a callback function deferred by calling :cpp:func:`esp_execute_shared_stack_function`, passing that function as parameter.
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Usage
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-----
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:cpp:func:`esp_execute_shared_stack_function` takes four arguments:
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- a mutex object allocated by the caller, which is used to protect if the same function shares its allocated stack
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- a pointer to the top of stack used for that fuction
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- the size of stack in bytes
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- a pointer to the shared stack function
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The user defined function will be deferred as a callback and can be called using the user allocated space without taking space from current task stack.
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The usage may look like the code below:
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.. code-block:: c
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void external_stack_function(void)
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{
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printf("Executing this printf from external stack! \n");
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}
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//Let's suppose we want to call printf using a separated stack space
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//allowing the app to reduce its stack size.
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void app_main()
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{
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//Allocate a stack buffer, from heap or as a static form:
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portSTACK_TYPE *shared_stack = malloc(8192 * sizeof(portSTACK_TYPE));
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assert(shared_stack != NULL);
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//Allocate a mutex to protect its usage:
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SemaphoreHandle_t printf_lock = xSemaphoreCreateMutex();
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assert(printf_lock != NULL);
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//Call the desired function using the macro helper:
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esp_execute_shared_stack_function(printf_lock,
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shared_stack,
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8192,
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external_stack_function);
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vSemaphoreDelete(printf_lock);
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free(shared_stack);
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}
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.. _esp-call-with-stack-basic_usage:
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API Reference
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-------------
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.. include-build-file:: inc/esp_expression_with_stack.inc
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