[429] | 1 | /** \addtogroup hal */
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| 2 | /** @{*/
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| 3 | /* mbed Microcontroller Library
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| 4 | * Copyright (c) 2006-2017 ARM Limited
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| 5 | *
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| 6 | * Licensed under the Apache License, Version 2.0 (the "License");
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| 7 | * you may not use this file except in compliance with the License.
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| 8 | * You may obtain a copy of the License at
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| 9 | *
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| 10 | * http://www.apache.org/licenses/LICENSE-2.0
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| 11 | *
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| 12 | * Unless required by applicable law or agreed to in writing, software
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| 13 | * distributed under the License is distributed on an "AS IS" BASIS,
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| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 15 | * See the License for the specific language governing permissions and
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| 16 | * limitations under the License.
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| 17 | */
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| 18 | #ifndef MBED_CRITICAL_SECTION_API_H
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| 19 | #define MBED_CRITICAL_SECTION_API_H
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| 20 |
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| 21 | #include <stdbool.h>
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| 22 |
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| 23 | #ifdef __cplusplus
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| 24 | extern "C" {
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| 25 | #endif
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| 26 |
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| 27 | /**
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| 28 | * \defgroup hal_critical Critical Section HAL functions
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| 29 | * @{
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| 30 | */
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| 31 |
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| 32 | /**
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| 33 | * Mark the start of a critical section
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| 34 | *
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| 35 | * This function will be called by core_util_critical_section_enter() each time
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| 36 | * the application requests to enter a critical section. The purpose of the
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| 37 | * critical section is to ensure mutual-exclusion synchronisation of the
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| 38 | * processor by preventing any change in processor control, the default
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| 39 | * behaviour requires storing the state of interrupts in the system before
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| 40 | * disabling them.
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| 41 | *
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| 42 | * The critical section code supports nesting. When a thread has entered a
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| 43 | * critical section it can make additional calls to
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| 44 | * core_util_critical_section_enter() without deadlocking itself. The critical
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| 45 | * section driver API tracks the number of nested calls to the critical section.
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| 46 | * The critical section will only be exited when
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| 47 | * core_util_critical_section_exit() has been called once for each time it
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| 48 | * entered the critical section.
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| 49 | *
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| 50 | * On the first call to enter a critical section this function MUST store the
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| 51 | * state of any interrupts or other application settings it will modify to
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| 52 | * facilitate the critical section.
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| 53 | *
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| 54 | * Each successive call to enter the critical section MUST ignore storing or
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| 55 | * modifying any application state.
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| 56 | *
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| 57 | * The default implementation of this function which will save the current state
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| 58 | * of interrupts before disabling them. This implementation can be found in
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| 59 | * mbed_critical_section_api.c. This behaviour is can be overridden on a per
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| 60 | * platform basis by providing a different implementation within the correct
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| 61 | * targets directory.
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| 62 | */
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| 63 | void hal_critical_section_enter(void);
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| 64 |
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| 65 |
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| 66 | /** Mark the end of a critical section.
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| 67 | *
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| 68 | * The purpose of this function is to restore any state that was modified upon
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| 69 | * entering the critical section, allowing other threads or interrupts to change
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| 70 | * the processor control.
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| 71 | *
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| 72 | * This function will be called once by core_util_critical_section_exit() per
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| 73 | * critical section on last call to exit. When called, the application MUST
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| 74 | * restore the saved interrupt/application state that was saved when entering
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| 75 | * the critical section.
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| 76 | *
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| 77 | * There is a default implementation of this function, it will restore the state
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| 78 | * of interrupts that were previously saved when hal_critical_section_enter was
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| 79 | * first called, this implementation can be found in
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| 80 | * mbed_critical_section_api.c. This behaviour is overridable by providing a
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| 81 | * different function implementation within the correct targets directory.
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| 82 | */
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| 83 | void hal_critical_section_exit(void);
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| 84 |
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| 85 |
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| 86 | /** Determine if the application is currently running in a critical section
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| 87 | *
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| 88 | * The purpose of this function is to inform the caller whether or not the
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| 89 | * application is running in a critical section. This is done by checking if
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| 90 | * the current interrupt state has been saved in the underlying implementation,
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| 91 | * this could also be done by checking the state of the interrupts at the time
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| 92 | * of calling.
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| 93 | *
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| 94 | * @return True if running in a critical section, false if not.
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| 95 | */
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| 96 | bool hal_in_critical_section(void);
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| 97 |
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| 98 |
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| 99 | /**@}*/
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| 100 |
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| 101 | #ifdef __cplusplus
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| 102 | }
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| 103 | #endif
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| 104 |
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| 105 | #endif // MBED_CRITICAL_SECTION_API_H
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| 106 |
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| 107 | /** @}*/
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