1 // Copyright 2020 The Pigweed Authors
3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
4 // use this file except in compliance with the License. You may obtain a copy of
7 // https://www.apache.org/licenses/LICENSE-2.0
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12 // License for the specific language governing permissions and limitations under
15 #include "pw_sync/binary_semaphore.h"
19 #include "pw_assert/assert.h"
20 #include "pw_chrono/system_clock.h"
21 #include "pw_chrono_threadx/system_clock_constants.h"
22 #include "pw_interrupt/context.h"
25 using pw::chrono::SystemClock;
26 using pw::chrono::threadx::kMaxTimeout;
30 bool BinarySemaphore::try_acquire_for(SystemClock::duration for_at_least) {
31 // Enforce the pw::sync::BinarySemaphore IRQ contract.
32 PW_DCHECK(!interrupt::InInterruptContext());
34 // Clamp negative durations to be 0 which maps to non-blocking.
35 for_at_least = std::max(for_at_least, SystemClock::duration::zero());
37 while (for_at_least > kMaxTimeout) {
38 const UINT result = tx_semaphore_get(&native_type_, kMaxTimeout.count());
39 if (result != TX_NO_INSTANCE) {
40 // If we didn't time out (TX_NO_INSTANCE), then we should have succeeded.
41 PW_CHECK_UINT_EQ(TX_SUCCESS, result);
44 for_at_least -= kMaxTimeout;
47 const UINT result = tx_semaphore_get(&native_type_, for_at_least.count());
48 if (result == TX_NO_INSTANCE) {
49 return false; // We timed out, there's still no token.
51 PW_CHECK_UINT_EQ(TX_SUCCESS, result);
55 } // namespace pw::sync