127 lines
4.3 KiB
C++
127 lines
4.3 KiB
C++
// Copyright 2021 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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#include "pw_sync/thread_notification.h"
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#include "FreeRTOS.h"
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#include "pw_assert/check.h"
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#include "pw_interrupt/context.h"
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#include "pw_sync_freertos/config.h"
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#include "task.h"
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namespace pw::sync {
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namespace {
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BaseType_t WaitForNotification(TickType_t xTicksToWait) {
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#ifdef configTASK_NOTIFICATION_ARRAY_ENTRIES
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return xTaskNotifyWaitIndexed(
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pw::sync::freertos::config::kThreadNotificationIndex,
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0, // Clear no bits on entry.
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0, // Clear no bits on exit.
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nullptr, // Don't care about the notification value.
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xTicksToWait);
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#else // !configTASK_NOTIFICATION_ARRAY_ENTRIES
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return xTaskNotifyWait(0, // Clear no bits on entry.
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0, // Clear no bits on exit.
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nullptr, // Don't care about the notification value.
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xTicksToWait);
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#endif // configTASK_NOTIFICATION_ARRAY_ENTRIES
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}
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} // namespace
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void ThreadNotification::acquire() {
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// Enforce the pw::sync::ThreadNotification IRQ contract.
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PW_DCHECK(!interrupt::InInterruptContext());
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// Enforce that only a single thread can block at a time.
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PW_DCHECK(native_type_.blocked_thread == nullptr);
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// Ensure that no one forgot to clean up nor corrupted the task notification
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// state in the TCB.
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PW_DCHECK(xTaskNotifyStateClear(nullptr) == pdFALSE);
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taskENTER_CRITICAL();
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if (native_type_.notified) {
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native_type_.notified = false;
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taskEXIT_CRITICAL();
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return;
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}
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// Not notified yet, set the task handle for a one-time notification.
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native_type_.blocked_thread = xTaskGetCurrentTaskHandle();
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taskEXIT_CRITICAL();
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#if INCLUDE_vTaskSuspend == 1 // This means portMAX_DELAY is indefinite.
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const BaseType_t result = WaitForNotification(portMAX_DELAY);
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PW_DCHECK_UINT_EQ(result, pdTRUE);
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#else // INCLUDE_vTaskSuspend != 1
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while (WaitForNotification(portMAX_DELAY) == pdFALSE) {
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}
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#endif // INCLUDE_vTaskSuspend
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taskENTER_CRITICAL();
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// The task handle was cleared by the notifier.
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// Note that this may hide another notification, however this is considered
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// a form of notification saturation just like as if this happened before
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// acquire() was invoked.
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native_type_.notified = false;
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taskEXIT_CRITICAL();
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}
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void ThreadNotification::release() {
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if (!interrupt::InInterruptContext()) { // Task context
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taskENTER_CRITICAL();
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if (native_type_.blocked_thread != nullptr) {
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#ifdef configTASK_NOTIFICATION_ARRAY_ENTRIES
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xTaskNotifyIndexed(native_type_.blocked_thread,
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pw::sync::freertos::config::kThreadNotificationIndex,
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0u,
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eNoAction);
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#else // !configTASK_NOTIFICATION_ARRAY_ENTRIES
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xTaskNotify(native_type_.blocked_thread, 0u, eNoAction);
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#endif // configTASK_NOTIFICATION_ARRAY_ENTRIES
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native_type_.blocked_thread = nullptr;
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}
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native_type_.notified = true;
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taskEXIT_CRITICAL();
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return;
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}
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// Interrupt context
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const UBaseType_t saved_interrupt_mask = taskENTER_CRITICAL_FROM_ISR();
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if (native_type_.blocked_thread != nullptr) {
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BaseType_t woke_higher_task = pdFALSE;
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#ifdef configTASK_NOTIFICATION_ARRAY_ENTRIES
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xTaskNotifyIndexedFromISR(
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native_type_.blocked_thread,
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pw::sync::freertos::config::kThreadNotificationIndex,
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0u,
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eNoAction,
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&woke_higher_task);
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#else // !configTASK_NOTIFICATION_ARRAY_ENTRIES
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xTaskNotifyFromISR(
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native_type_.blocked_thread, 0u, eNoAction, &woke_higher_task);
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#endif // configTASK_NOTIFICATION_ARRAY_ENTRIES
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native_type_.blocked_thread = nullptr;
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portYIELD_FROM_ISR(woke_higher_task);
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}
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native_type_.notified = true;
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taskEXIT_CRITICAL_FROM_ISR(saved_interrupt_mask);
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}
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} // namespace pw::sync
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