57 lines
2.1 KiB
C++
57 lines
2.1 KiB
C++
// Copyright 2020 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_thread/sleep.h"
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#include <algorithm>
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#include "FreeRTOS.h"
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#include "pw_assert/check.h"
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#include "pw_chrono/system_clock.h"
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#include "pw_chrono_freertos/system_clock_constants.h"
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#include "pw_thread/id.h"
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#include "task.h"
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using pw::chrono::SystemClock;
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namespace pw::this_thread {
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void sleep_for(SystemClock::duration sleep_duration) {
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// Ensure this is being called by a thread.
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PW_DCHECK(get_id() != thread::Id());
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// Yield for negative and zero length durations.
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if (sleep_duration <= SystemClock::duration::zero()) {
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taskYIELD();
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return;
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}
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// In case the timeout is too long for us to express through the native
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// FreeRTOS API, we repeatedly wait with shorter durations. Note that on a
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// tick based kernel we cannot tell how far along we are on the current tick,
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// ergo we add one whole tick to the final duration. However, this also means
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// that the loop must ensure that timeout + 1 is less than the max timeout.
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constexpr SystemClock::duration kMaxTimeoutMinusOne =
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pw::chrono::freertos::kMaxTimeout - SystemClock::duration(1);
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while (sleep_duration > kMaxTimeoutMinusOne) {
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vTaskDelay(static_cast<TickType_t>(kMaxTimeoutMinusOne.count()));
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sleep_duration -= kMaxTimeoutMinusOne;
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}
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// On a tick based kernel we cannot tell how far along we are on the current
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// tick, ergo we add one whole tick to the final duration.
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vTaskDelay(static_cast<TickType_t>(sleep_duration.count() + 1));
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}
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} // namespace pw::this_thread
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