esp-idf/components/xtensa/expression_with_stack_xtensa.c

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// Copyright 2015-2019 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <esp_expression_with_stack.h>
#include <freertos/xtensa_rtos.h>
#include <freertos/xtensa_context.h>
#include <setjmp.h>
#include <string.h>
StackType_t *xtensa_shared_stack;
shared_stack_function xtensa_shared_stack_callback;
jmp_buf xtensa_shared_stack_env;
bool xtensa_shared_stack_function_done = false;
static portMUX_TYPE xtensa_shared_stack_spinlock = portMUX_INITIALIZER_UNLOCKED;
static void *current_task_stack = NULL;
extern void esp_shared_stack_invoke_function(void);
static void esp_switch_stack_setup(StackType_t *stack, size_t stack_size)
{
#if CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK
esp_clear_watchpoint(1);
uint32_t watchpoint_place = ((uint32_t)stack + 32) & ~0x1f ;
#endif
//We need also to tweak current task stackpointer to avoid erroneous
//stack overflow indication, so fills the stack with freertos known pattern:
memset(stack, 0xa5U, stack_size * sizeof(StackType_t));
StaticTask_t *current = (StaticTask_t *)xTaskGetCurrentTaskHandle();
//Then put the fake stack inside of TCB:
current_task_stack = current->pxDummy6;
current->pxDummy6 = (void *)stack;
StackType_t *top_of_stack = stack + stack_size;
//Align stack to a 16byte boundary, as required by CPU specific:
top_of_stack = (StackType_t *)(((UBaseType_t)(top_of_stack - 16) & ~0xf));
#if CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK
esp_set_watchpoint(1, (uint8_t *)watchpoint_place, 32, ESP_WATCHPOINT_STORE);
#endif
xtensa_shared_stack = top_of_stack;
}
void esp_execute_shared_stack_function(SemaphoreHandle_t lock, void *stack, size_t stack_size, shared_stack_function function)
{
assert(lock);
assert(stack);
assert(stack_size > 0 && stack_size >= CONFIG_ESP_MINIMAL_SHARED_STACK_SIZE);
assert(function);
xSemaphoreTake(lock, portMAX_DELAY);
portENTER_CRITICAL(&xtensa_shared_stack_spinlock);
xtensa_shared_stack_function_done = false;
esp_switch_stack_setup(stack, stack_size);
xtensa_shared_stack_callback = function;
portEXIT_CRITICAL(&xtensa_shared_stack_spinlock);
setjmp(xtensa_shared_stack_env);
if(!xtensa_shared_stack_function_done) {
esp_shared_stack_invoke_function();
}
portENTER_CRITICAL(&xtensa_shared_stack_spinlock);
StaticTask_t *current = (StaticTask_t *)xTaskGetCurrentTaskHandle();
//Restore current task stack:
current->pxDummy6 = (StackType_t *)current_task_stack;
vPortSetStackWatchpoint(current->pxDummy6);
portEXIT_CRITICAL(&xtensa_shared_stack_spinlock);
xSemaphoreGive(lock);
}