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62 lines
2.0 KiB
62 lines
2.0 KiB
// 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_sync/binary_semaphore.h"
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#include <algorithm>
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#include "FreeRTOS.h"
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#include "pw_assert/assert.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_interrupt/context.h"
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#include "semphr.h"
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using pw::chrono::SystemClock;
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namespace pw::sync {
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namespace {
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static_assert(configSUPPORT_STATIC_ALLOCATION != 0,
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"FreeRTOS static allocations are required for this backend.");
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} // namespace
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bool BinarySemaphore::try_acquire_for(SystemClock::duration for_at_least) {
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PW_DCHECK(!interrupt::InInterruptContext());
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// Use non-blocking try_acquire for negative and zero length durations.
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if (for_at_least <= SystemClock::duration::zero()) {
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return try_acquire();
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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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constexpr SystemClock::duration kMaxTimeoutMinusOne =
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pw::chrono::freertos::kMaxTimeout - SystemClock::duration(1);
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while (for_at_least > kMaxTimeoutMinusOne) {
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if (xSemaphoreTake(&native_type_,
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static_cast<TickType_t>(kMaxTimeoutMinusOne.count())) ==
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pdTRUE) {
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return true;
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}
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for_at_least -= kMaxTimeoutMinusOne;
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}
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return xSemaphoreTake(&native_type_,
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static_cast<TickType_t>(for_at_least.count() + 1)) ==
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pdTRUE;
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}
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} // namespace pw::sync
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