Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 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_sync/counting_semaphore.h" |
| 16 | |
| 17 | #include <algorithm> |
| 18 | |
| 19 | #include "FreeRTOS.h" |
Wyatt Hepler | f298de4 | 2021-03-19 15:06:36 -0700 | [diff] [blame] | 20 | #include "pw_assert/check.h" |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 21 | #include "pw_chrono/system_clock.h" |
| 22 | #include "pw_chrono_freertos/system_clock_constants.h" |
| 23 | #include "pw_interrupt/context.h" |
| 24 | #include "semphr.h" |
| 25 | |
| 26 | using pw::chrono::SystemClock; |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 27 | |
| 28 | namespace pw::sync { |
| 29 | namespace { |
| 30 | |
| 31 | static_assert(configUSE_COUNTING_SEMAPHORES != 0, |
| 32 | "FreeRTOS counting semaphores aren't enabled."); |
| 33 | |
Ewout van Bekkum | 3a00cda | 2021-03-09 13:56:52 -0800 | [diff] [blame] | 34 | static_assert(configSUPPORT_STATIC_ALLOCATION != 0, |
| 35 | "FreeRTOS static allocations are required for this backend."); |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 36 | |
| 37 | } // namespace |
| 38 | |
| 39 | void CountingSemaphore::release(ptrdiff_t update) { |
| 40 | if (interrupt::InInterruptContext()) { |
| 41 | for (; update > 0; --update) { |
| 42 | BaseType_t woke_higher_task = pdFALSE; |
Scott James Remnant | d6f5475 | 2021-07-26 17:32:54 -0700 | [diff] [blame] | 43 | const BaseType_t result = xSemaphoreGiveFromISR( |
| 44 | reinterpret_cast<SemaphoreHandle_t>(&native_type_), |
| 45 | &woke_higher_task); |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 46 | PW_DCHECK_UINT_EQ(result, pdTRUE, "Overflowed counting semaphore."); |
| 47 | portYIELD_FROM_ISR(woke_higher_task); |
| 48 | } |
| 49 | } else { // Task context |
| 50 | for (; update > 0; --update) { |
Scott James Remnant | d6f5475 | 2021-07-26 17:32:54 -0700 | [diff] [blame] | 51 | const BaseType_t result = |
| 52 | xSemaphoreGive(reinterpret_cast<SemaphoreHandle_t>(&native_type_)); |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 53 | PW_DCHECK_UINT_EQ(result, pdTRUE, "Overflowed counting semaphore."); |
| 54 | } |
| 55 | } |
| 56 | } |
| 57 | |
Ewout van Bekkum | 5ff8cc5 | 2021-09-07 15:46:36 -0700 | [diff] [blame] | 58 | bool CountingSemaphore::try_acquire_for(SystemClock::duration timeout) { |
Ewout van Bekkum | a6642d7 | 2021-11-05 09:43:14 -0700 | [diff] [blame] | 59 | // Enforce the pw::sync::CountingSemaphore IRQ contract. |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 60 | PW_DCHECK(!interrupt::InInterruptContext()); |
Ewout van Bekkum | 3a00cda | 2021-03-09 13:56:52 -0800 | [diff] [blame] | 61 | |
Ewout van Bekkum | a6ad4da | 2021-03-10 12:11:16 -0800 | [diff] [blame] | 62 | // Use non-blocking try_acquire for negative and zero length durations. |
Ewout van Bekkum | 5ff8cc5 | 2021-09-07 15:46:36 -0700 | [diff] [blame] | 63 | if (timeout <= SystemClock::duration::zero()) { |
Ewout van Bekkum | 3a00cda | 2021-03-09 13:56:52 -0800 | [diff] [blame] | 64 | return try_acquire(); |
| 65 | } |
| 66 | |
Ewout van Bekkum | a6642d7 | 2021-11-05 09:43:14 -0700 | [diff] [blame] | 67 | // In case the timeout is too long for us to express through the native |
| 68 | // FreeRTOS API, we repeatedly wait with shorter durations. Note that on a |
| 69 | // tick based kernel we cannot tell how far along we are on the current tick, |
| 70 | // ergo we add one whole tick to the final duration. However, this also means |
| 71 | // that the loop must ensure that timeout + 1 is less than the max timeout. |
Ewout van Bekkum | 3a00cda | 2021-03-09 13:56:52 -0800 | [diff] [blame] | 72 | constexpr SystemClock::duration kMaxTimeoutMinusOne = |
| 73 | pw::chrono::freertos::kMaxTimeout - SystemClock::duration(1); |
Ewout van Bekkum | 5ff8cc5 | 2021-09-07 15:46:36 -0700 | [diff] [blame] | 74 | while (timeout > kMaxTimeoutMinusOne) { |
Scott James Remnant | d6f5475 | 2021-07-26 17:32:54 -0700 | [diff] [blame] | 75 | if (xSemaphoreTake(reinterpret_cast<SemaphoreHandle_t>(&native_type_), |
Ewout van Bekkum | a6ad4da | 2021-03-10 12:11:16 -0800 | [diff] [blame] | 76 | static_cast<TickType_t>(kMaxTimeoutMinusOne.count())) == |
| 77 | pdTRUE) { |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 78 | return true; |
| 79 | } |
Ewout van Bekkum | 5ff8cc5 | 2021-09-07 15:46:36 -0700 | [diff] [blame] | 80 | timeout -= kMaxTimeoutMinusOne; |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 81 | } |
Ewout van Bekkum | a6642d7 | 2021-11-05 09:43:14 -0700 | [diff] [blame] | 82 | // On a tick based kernel we cannot tell how far along we are on the current |
| 83 | // tick, ergo we add one whole tick to the final duration. |
Scott James Remnant | d6f5475 | 2021-07-26 17:32:54 -0700 | [diff] [blame] | 84 | return xSemaphoreTake(reinterpret_cast<SemaphoreHandle_t>(&native_type_), |
Ewout van Bekkum | 5ff8cc5 | 2021-09-07 15:46:36 -0700 | [diff] [blame] | 85 | static_cast<TickType_t>(timeout.count() + 1)) == pdTRUE; |
Ewout van Bekkum | 660ebba | 2020-11-11 13:40:10 -0800 | [diff] [blame] | 86 | } |
| 87 | |
| 88 | } // namespace pw::sync |