57 lines
1.9 KiB
ReStructuredText
57 lines
1.9 KiB
ReStructuredText
Call function with external stack
|
|
=================================
|
|
|
|
Overview
|
|
--------
|
|
|
|
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 macro :cpp:func:`ESP_EXECUTE_EXPRESSION_WITH_STACK`
|
|
it will redirect the target function to be executed using the space
|
|
allocated by the user.
|
|
|
|
Usage
|
|
-----
|
|
|
|
:cpp:func:`ESP_EXECUTE_EXPRESSION_WITH_STACK` takes three arguments,
|
|
a mutex object allocated by the caller, which is used to protect if
|
|
the same function shares its allocated stack, a pointer to the top
|
|
of stack used to that fuction, and the function itself, note the
|
|
function is passed exactly in the same way as do when you call
|
|
it on a regular way.
|
|
|
|
The usage may looks like the code below:
|
|
|
|
.. code-block:: c
|
|
|
|
//Let's suppose we wanting to call printf using a separated stack space
|
|
//allowing app to reduce its stack size.
|
|
void app_main()
|
|
{
|
|
//Allocate a stack buffer, from heap or as a static form:
|
|
portSTACK_TYPE *shared_stack = malloc(8192 * sizeof(portSTACK_TYPE));
|
|
assert(shared_stack != NULL);
|
|
|
|
//Allocate a mutex to protect its usage:
|
|
SemaphoreHandle_t printf_lock = xSemaphoreCreateMutex();
|
|
assert(printf_lock != NULL);
|
|
|
|
//Call the desired function using the macro helper:
|
|
ESP_EXECUTE_EXPRESSION_WITH_STACK(printf_lock,
|
|
shared_stack,
|
|
printf("Executing this from external stack! \n"));
|
|
vSemaphoreDelete(printf_lock);
|
|
free(shared_stack);
|
|
}
|
|
|
|
.. _esp-call-with-stack-basic_usage:
|
|
|
|
API Reference
|
|
-------------
|
|
|
|
.. include-build-file:: inc/esp_expression_with_stack.inc
|
|
|
|
|