Chapter 2. API Reference
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 shared stack space which is a callback function deferred
by calling esp_execute_shared_stack_function(), passing that function as parameter
Usage
esp_execute_shared_stack_function() takes four 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, the size in bytes of stack and, a pointer to a user function where the shared stack space will reside, after
calling the function, the user defined function will be deferred as a callback where functions can be called using the
user allocated space without taking space from current task stack.
The usage may looks like the code below:
void external_stack_function(void)
{
printf("Executing this printf from external stack! \n");
}
//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_shared_stack_function(printf_lock,
shared_stack,
8192,
external_stack_function);
vSemaphoreDelete(printf_lock);
free(shared_stack);
}
API Reference
Header File
• components/esp_system/include/esp_expression_with_stack.h
Functions
void esp_execute_shared_stack_function(SemaphoreHandle_t lock, void *stack, size_t
stack_size, shared_stack_function function)
Calls user defined shared stack space function.
Note if either lock, stack or stack size is invalid, the expression will be called using the current stack.
Parameters
• lock: Mutex object to protect in case of shared stack
• stack: Pointer to user alocated stack
Espressif Systems 999
Submit Document Feedback
Release v4.4
To Next Page
Loading...