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hal/critical_section_api.h@170:e95d10626187, 2018-09-06 (annotated)
- Committer:
- AnnaBridge
- Date:
- Thu Sep 06 13:39:34 2018 +0100
- Revision:
- 170:e95d10626187
- Parent:
- 165:d1b4690b3f8b
- Child:
- 172:65be27845400
mbed library. Release version 163
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
AnnaBridge | 165:d1b4690b3f8b | 1 | /** \addtogroup hal */ |
AnnaBridge | 165:d1b4690b3f8b | 2 | /** @{*/ |
AnnaBridge | 165:d1b4690b3f8b | 3 | /* mbed Microcontroller Library |
AnnaBridge | 165:d1b4690b3f8b | 4 | * Copyright (c) 2006-2017 ARM Limited |
AnnaBridge | 165:d1b4690b3f8b | 5 | * |
AnnaBridge | 165:d1b4690b3f8b | 6 | * Licensed under the Apache License, Version 2.0 (the "License"); |
AnnaBridge | 165:d1b4690b3f8b | 7 | * you may not use this file except in compliance with the License. |
AnnaBridge | 165:d1b4690b3f8b | 8 | * You may obtain a copy of the License at |
AnnaBridge | 165:d1b4690b3f8b | 9 | * |
AnnaBridge | 165:d1b4690b3f8b | 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
AnnaBridge | 165:d1b4690b3f8b | 11 | * |
AnnaBridge | 165:d1b4690b3f8b | 12 | * Unless required by applicable law or agreed to in writing, software |
AnnaBridge | 165:d1b4690b3f8b | 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
AnnaBridge | 165:d1b4690b3f8b | 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
AnnaBridge | 165:d1b4690b3f8b | 15 | * See the License for the specific language governing permissions and |
AnnaBridge | 165:d1b4690b3f8b | 16 | * limitations under the License. |
AnnaBridge | 165:d1b4690b3f8b | 17 | */ |
AnnaBridge | 165:d1b4690b3f8b | 18 | #ifndef MBED_CRITICAL_SECTION_API_H |
AnnaBridge | 165:d1b4690b3f8b | 19 | #define MBED_CRITICAL_SECTION_API_H |
AnnaBridge | 165:d1b4690b3f8b | 20 | |
AnnaBridge | 165:d1b4690b3f8b | 21 | #include <stdbool.h> |
AnnaBridge | 165:d1b4690b3f8b | 22 | |
AnnaBridge | 165:d1b4690b3f8b | 23 | #ifdef __cplusplus |
AnnaBridge | 165:d1b4690b3f8b | 24 | extern "C" { |
AnnaBridge | 165:d1b4690b3f8b | 25 | #endif |
AnnaBridge | 165:d1b4690b3f8b | 26 | |
AnnaBridge | 165:d1b4690b3f8b | 27 | /** |
AnnaBridge | 165:d1b4690b3f8b | 28 | * \defgroup hal_critical Critical Section HAL functions |
AnnaBridge | 165:d1b4690b3f8b | 29 | * @{ |
AnnaBridge | 165:d1b4690b3f8b | 30 | */ |
AnnaBridge | 165:d1b4690b3f8b | 31 | |
AnnaBridge | 165:d1b4690b3f8b | 32 | /** |
AnnaBridge | 165:d1b4690b3f8b | 33 | * Mark the start of a critical section |
AnnaBridge | 165:d1b4690b3f8b | 34 | * |
AnnaBridge | 165:d1b4690b3f8b | 35 | * This function will be called by core_util_critical_section_enter() each time |
AnnaBridge | 165:d1b4690b3f8b | 36 | * the application requests to enter a critical section. The purpose of the |
AnnaBridge | 165:d1b4690b3f8b | 37 | * critical section is to ensure mutual-exclusion synchronisation of the |
AnnaBridge | 165:d1b4690b3f8b | 38 | * processor by preventing any change in processor control, the default |
AnnaBridge | 165:d1b4690b3f8b | 39 | * behaviour requires storing the state of interrupts in the system before |
AnnaBridge | 165:d1b4690b3f8b | 40 | * disabling them. |
AnnaBridge | 165:d1b4690b3f8b | 41 | * |
AnnaBridge | 165:d1b4690b3f8b | 42 | * The critical section code supports nesting. When a thread has entered a |
AnnaBridge | 165:d1b4690b3f8b | 43 | * critical section it can make additional calls to |
AnnaBridge | 165:d1b4690b3f8b | 44 | * core_util_critical_section_enter() without deadlocking itself. The critical |
AnnaBridge | 165:d1b4690b3f8b | 45 | * section driver API tracks the number of nested calls to the critical section. |
AnnaBridge | 165:d1b4690b3f8b | 46 | * The critical section will only be exited when |
AnnaBridge | 165:d1b4690b3f8b | 47 | * core_util_critical_section_exit() has been called once for each time it |
AnnaBridge | 165:d1b4690b3f8b | 48 | * entered the critical section. |
AnnaBridge | 165:d1b4690b3f8b | 49 | * |
AnnaBridge | 165:d1b4690b3f8b | 50 | * On the first call to enter a critical section this function MUST store the |
AnnaBridge | 165:d1b4690b3f8b | 51 | * state of any interrupts or other application settings it will modify to |
AnnaBridge | 165:d1b4690b3f8b | 52 | * facilitate the critical section. |
AnnaBridge | 165:d1b4690b3f8b | 53 | * |
AnnaBridge | 165:d1b4690b3f8b | 54 | * Each successive call to enter the critical section MUST ignore storing or |
AnnaBridge | 165:d1b4690b3f8b | 55 | * modifying any application state. |
AnnaBridge | 165:d1b4690b3f8b | 56 | * |
AnnaBridge | 165:d1b4690b3f8b | 57 | * The default implementation of this function which will save the current state |
AnnaBridge | 165:d1b4690b3f8b | 58 | * of interrupts before disabling them. This implementation can be found in |
AnnaBridge | 165:d1b4690b3f8b | 59 | * mbed_critical_section_api.c. This behaviour is can be overridden on a per |
AnnaBridge | 165:d1b4690b3f8b | 60 | * platform basis by providing a different implementation within the correct |
AnnaBridge | 165:d1b4690b3f8b | 61 | * targets directory. |
AnnaBridge | 165:d1b4690b3f8b | 62 | */ |
AnnaBridge | 165:d1b4690b3f8b | 63 | void hal_critical_section_enter(void); |
AnnaBridge | 165:d1b4690b3f8b | 64 | |
AnnaBridge | 165:d1b4690b3f8b | 65 | |
AnnaBridge | 165:d1b4690b3f8b | 66 | /** Mark the end of a critical section. |
AnnaBridge | 165:d1b4690b3f8b | 67 | * |
AnnaBridge | 165:d1b4690b3f8b | 68 | * The purpose of this function is to restore any state that was modified upon |
AnnaBridge | 165:d1b4690b3f8b | 69 | * entering the critical section, allowing other threads or interrupts to change |
AnnaBridge | 165:d1b4690b3f8b | 70 | * the processor control. |
AnnaBridge | 165:d1b4690b3f8b | 71 | * |
AnnaBridge | 165:d1b4690b3f8b | 72 | * This function will be called once by core_util_critical_section_exit() per |
AnnaBridge | 165:d1b4690b3f8b | 73 | * critical section on last call to exit. When called, the application MUST |
AnnaBridge | 165:d1b4690b3f8b | 74 | * restore the saved interrupt/application state that was saved when entering |
AnnaBridge | 165:d1b4690b3f8b | 75 | * the critical section. |
AnnaBridge | 165:d1b4690b3f8b | 76 | * |
AnnaBridge | 165:d1b4690b3f8b | 77 | * There is a default implementation of this function, it will restore the state |
AnnaBridge | 165:d1b4690b3f8b | 78 | * of interrupts that were previously saved when hal_critical_section_enter was |
AnnaBridge | 165:d1b4690b3f8b | 79 | * first called, this implementation can be found in |
AnnaBridge | 165:d1b4690b3f8b | 80 | * mbed_critical_section_api.c. This behaviour is overridable by providing a |
AnnaBridge | 165:d1b4690b3f8b | 81 | * different function implementation within the correct targets directory. |
AnnaBridge | 165:d1b4690b3f8b | 82 | */ |
AnnaBridge | 165:d1b4690b3f8b | 83 | void hal_critical_section_exit(void); |
AnnaBridge | 165:d1b4690b3f8b | 84 | |
AnnaBridge | 165:d1b4690b3f8b | 85 | |
AnnaBridge | 165:d1b4690b3f8b | 86 | /** Determine if the application is currently running in a critical section |
AnnaBridge | 165:d1b4690b3f8b | 87 | * |
AnnaBridge | 165:d1b4690b3f8b | 88 | * The purpose of this function is to inform the caller whether or not the |
AnnaBridge | 165:d1b4690b3f8b | 89 | * application is running in a critical section. This is done by checking if |
AnnaBridge | 165:d1b4690b3f8b | 90 | * the current interrupt state has been saved in the underlying implementation, |
AnnaBridge | 165:d1b4690b3f8b | 91 | * this could also be done by checking the state of the interrupts at the time |
AnnaBridge | 165:d1b4690b3f8b | 92 | * of calling. |
AnnaBridge | 165:d1b4690b3f8b | 93 | * |
AnnaBridge | 165:d1b4690b3f8b | 94 | * @return True if running in a critical section, false if not. |
AnnaBridge | 165:d1b4690b3f8b | 95 | */ |
AnnaBridge | 165:d1b4690b3f8b | 96 | bool hal_in_critical_section(void); |
AnnaBridge | 165:d1b4690b3f8b | 97 | |
AnnaBridge | 165:d1b4690b3f8b | 98 | |
AnnaBridge | 165:d1b4690b3f8b | 99 | /**@}*/ |
AnnaBridge | 165:d1b4690b3f8b | 100 | |
AnnaBridge | 165:d1b4690b3f8b | 101 | #ifdef __cplusplus |
AnnaBridge | 165:d1b4690b3f8b | 102 | } |
AnnaBridge | 165:d1b4690b3f8b | 103 | #endif |
AnnaBridge | 165:d1b4690b3f8b | 104 | |
AnnaBridge | 165:d1b4690b3f8b | 105 | #endif // MBED_CRITICAL_SECTION_API_H |
AnnaBridge | 165:d1b4690b3f8b | 106 | |
AnnaBridge | 165:d1b4690b3f8b | 107 | /** @}*/ |