blob: 8f7b132c5dde02e90a032011f13ae98e0274c71c [file] [log] [blame]
// Copyright 2020 The Pigweed Authors
// 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
// 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 "pw_sync/binary_semaphore.h"
#include <algorithm>
#include "FreeRTOS.h"
#include "pw_assert/check.h"
#include "pw_chrono/system_clock.h"
#include "pw_chrono_freertos/system_clock_constants.h"
#include "pw_interrupt/context.h"
#include "semphr.h"
using pw::chrono::SystemClock;
namespace pw::sync {
namespace {
static_assert(configSUPPORT_STATIC_ALLOCATION != 0,
"FreeRTOS static allocations are required for this backend.");
} // namespace
bool BinarySemaphore::try_acquire_for(SystemClock::duration for_at_least) {
// Use non-blocking try_acquire for negative and zero length durations.
if (for_at_least <= SystemClock::duration::zero()) {
return try_acquire();
// On a tick based kernel we cannot tell how far along we are on the current
// tick, ergo we add one whole tick to the final duration.
constexpr SystemClock::duration kMaxTimeoutMinusOne =
pw::chrono::freertos::kMaxTimeout - SystemClock::duration(1);
while (for_at_least > kMaxTimeoutMinusOne) {
if (xSemaphoreTake(&native_type_,
static_cast<TickType_t>(kMaxTimeoutMinusOne.count())) ==
pdTRUE) {
return true;
for_at_least -= kMaxTimeoutMinusOne;
return xSemaphoreTake(&native_type_,
static_cast<TickType_t>(for_at_least.count() + 1)) ==
} // namespace pw::sync