esp-idf/components/freertos/test/test_fpu_in_task.c

/*
 * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include "sdkconfig.h"
#include <math.h>
#include "soc/soc_caps.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#include "unity.h"
#include "test_utils.h"

#if SOC_CPU_HAS_FPU

/* ------------------------------------------------------------------------------------------------------------------ */

/*
Test FPU usage from a task context

Purpose:
    - Test that the FPU can be used from a task context
    - Test that FPU context is properly saved and restored
Procedure:
    - Create TEST_PINNED_NUM_TASKS tasks pinned to each core
    - Start each task
    - Each task updates a float variable and then blocks (to allow other tasks to run thus forcing the an FPU context
      save and restore).
Expected:
    - Correct float value calculated by each task
*/

#define TEST_PINNED_NUM_TASKS       3

static void pinned_task(void *arg)
{
    ulTaskNotifyTake(pdTRUE, portMAX_DELAY);

    /*
    Use the FPU
    - We test using a calculation that will cause a change in mantissa and exponent for extra thoroughness
    - cosf(0.0f) should return 1.0f, thus we are simply doubling test_float every iteration.
    - Therefore, we should end up with (0.01) * (2^8) = 2.56 at the end of the loop
    */
    volatile float test_float = 0.01f;
    for (int i = 0; i < 8; i++) {
        test_float = test_float * 2.0f * cosf(0.0f);
        vTaskDelay(1);  // Block to cause a context switch, forcing the FPU context to be saved
    }
    // We allow a 0.1% delta on the final result in case of any loss of precision from floating point calculations
    TEST_ASSERT_FLOAT_WITHIN(0.00256f, 2.56f, test_float);

    // Indicate done wand wait to be deleted
    xSemaphoreGive((SemaphoreHandle_t)arg);
    vTaskSuspend(NULL);
}

TEST_CASE("FPU: Usage in task", "[freertos]")
{
    SemaphoreHandle_t done_sem = xSemaphoreCreateCounting(configNUM_CORES * TEST_PINNED_NUM_TASKS, 0);
    TEST_ASSERT_NOT_EQUAL(NULL, done_sem);

    TaskHandle_t task_handles[configNUM_CORES][TEST_PINNED_NUM_TASKS];

    // Create test tasks for each core
    for (int i = 0; i < configNUM_CORES; i++) {
        for (int j = 0; j < TEST_PINNED_NUM_TASKS; j++) {
            TEST_ASSERT_EQUAL(pdTRUE, xTaskCreatePinnedToCore(pinned_task, "task", 4096, (void *)done_sem, UNITY_FREERTOS_PRIORITY + 1, &task_handles[i][j], i));
        }
    }

    // Start the created tasks simultaneously
    for (int i = 0; i < configNUM_CORES; i++) {
        for (int j = 0; j < TEST_PINNED_NUM_TASKS; j++) {
            xTaskNotifyGive(task_handles[i][j]);
        }
    }

    // Wait for the tasks to complete
    for (int i = 0; i < configNUM_CORES * TEST_PINNED_NUM_TASKS; i++) {
        xSemaphoreTake(done_sem, portMAX_DELAY);
    }

    // Delete the tasks
    for (int i = 0; i < configNUM_CORES; i++) {
        for (int j = 0; j < TEST_PINNED_NUM_TASKS; j++) {
            vTaskDelete(task_handles[i][j]);
        }
    }

    vTaskDelay(10); // Short delay to allow idle task to be free task memory and FPU contexts
    vSemaphoreDelete(done_sem);
}

/* ------------------------------------------------------------------------------------------------------------------ */

/*
Test FPU usage will pin an unpinned task

Purpose:
    - Test that unpinned tasks are automatically pinned to the current core on the task's first use of the FPU
Procedure:
    - Create an unpinned task
    - Task disables scheduling/preemption to ensure that it does not switch cores
    - Task uses the FPU
    - Task checks its core affinity after FPU usage
Expected:
    - Task remains unpinned until its first usage of the FPU
    - The task becomes pinned to the current core after first use of the FPU
*/

#if configNUM_CORES > 1

static void unpinned_task(void *arg)
{
    // Disable scheduling to make sure current core ID doesn't change
    vTaskSuspendAll();

    BaseType_t cur_core_num = xPortGetCoreID();
    // Check that the task is unpinned
    TEST_ASSERT_EQUAL(tskNO_AFFINITY, xTaskGetAffinity(NULL));

    /*
    Use the FPU
    - We test using a calculation that will cause a change in mantissa and exponent for extra thoroughness
    - cosf(0.0f) should return 1.0f, thus we are simply doubling test_float every iteration.
    - Therefore, we should end up with (0.01) * (2^8) = 2.56 at the end of the loop
    */
    volatile float test_float = 0.01f;
    for (int i = 0; i < 8; i++) {
        test_float = test_float * 2.0f * cosf(0.0f);
    }
    // We allow a 0.1% delta on the final result in case of any loss of precision from floating point calculations
    TEST_ASSERT_FLOAT_WITHIN(0.00256f, 2.56f, test_float);

    TEST_ASSERT_EQUAL(cur_core_num, xTaskGetAffinity(NULL));

    // Reenable scheduling
    xTaskResumeAll();

    // Indicate done and self delete
    xTaskNotifyGive((TaskHandle_t)arg);
    vTaskDelete(NULL);
}

TEST_CASE("FPU: Usage in unpinned task", "[freertos]")
{
    TaskHandle_t unity_task_handle = xTaskGetCurrentTaskHandle();
    // Create unpinned task
    xTaskCreate(unpinned_task, "unpin", 4096, (void *)unity_task_handle, UNITY_FREERTOS_PRIORITY + 1, NULL);
    // Wait for task to complete
    ulTaskNotifyTake(pdTRUE, portMAX_DELAY);
    vTaskDelay(10); // Short delay to allow task memory to be freed
}

#endif // configNUM_CORES > 1
#endif // SOC_CPU_HAS_FPU