1 // Copyright 2020 The Pigweed Authors
2 //
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
5 // the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
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
13 // the License.
14
15 #include "pw_thread/sleep.h"
16
17 #include <algorithm>
18
19 #include "pw_assert/check.h"
20 #include "pw_chrono/system_clock.h"
21 #include "pw_chrono_threadx/system_clock_constants.h"
22 #include "pw_thread/thread.h"
23 #include "tx_api.h"
24
25 using pw::chrono::SystemClock;
26
27 namespace pw::this_thread {
28
sleep_for(chrono::SystemClock::duration sleep_duration)29 void sleep_for(chrono::SystemClock::duration sleep_duration) {
30 // Ensure this is being called by a thread.
31 PW_DCHECK(get_id() != Thread::id());
32
33 // Yield for negative and zero length durations.
34 if (sleep_duration <= chrono::SystemClock::duration::zero()) {
35 tx_thread_relinquish();
36 return;
37 }
38
39 // In case the timeout is too long for us to express through the native
40 // ThreadX API, we repeatedly wait with shorter durations. Note that on a tick
41 // based kernel we cannot tell how far along we are on the current tick, ergo
42 // we add one whole tick to the final duration. However, this also means that
43 // the loop must ensure that timeout + 1 is less than the max timeout.
44 constexpr SystemClock::duration kMaxTimeoutMinusOne =
45 pw::chrono::threadx::kMaxTimeout - SystemClock::duration(1);
46 while (sleep_duration > kMaxTimeoutMinusOne) {
47 const UINT result =
48 tx_thread_sleep(static_cast<ULONG>(kMaxTimeoutMinusOne.count()));
49 PW_CHECK_UINT_EQ(TX_SUCCESS, result);
50 sleep_duration -= kMaxTimeoutMinusOne;
51 }
52 // On a tick based kernel we cannot tell how far along we are on the current
53 // tick, ergo we add one whole tick to the final duration.
54 const UINT result =
55 tx_thread_sleep(static_cast<ULONG>(sleep_duration.count() + 1));
56 PW_CHECK_UINT_EQ(TX_SUCCESS, result);
57 }
58
59 } // namespace pw::this_thread
60