56 lines
1.9 KiB
ReStructuredText
56 lines
1.9 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
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which is independent of current task stack, this mechanism can be
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used to save stack space wasted by tasks which call a common function
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with intensive stack usage such as `printf`. The given function can
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be called inside the macro :cpp:func:`ESP_EXECUTE_EXPRESSION_WITH_STACK`
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it will redirect the target function to be executed using the space
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allocated by the user.
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Usage
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-----
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:cpp:func:`ESP_EXECUTE_EXPRESSION_WITH_STACK` takes three arguments,
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a mutex object allocated by the caller, which is used to protect if
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the same function shares its allocated stack, a pointer to the top
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of stack used to that fuction, and the function itself, note the
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function is passed exactly in the same way as do when you call
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it on a regular way.
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The usage may looks like the code below:
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.. code-block:: c
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//Let's suppose we wanting to call printf using a separated stack space
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//allowing 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_EXPRESSION_WITH_STACK(printf_lock,
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shared_stack,
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printf("Executing this from external stack! \n"));
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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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