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hal/critical_section_api.h@186:9c2029bfadbe, 2018-04-20 (annotated)

Committer:
Anna Bridge
Date:
Fri Apr 20 11:31:35 2018 +0100
Revision:
186:9c2029bfadbe
Parent:
185:08ed48f1de7f 
Update to latest version of mbed lib

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AnnaBridge 185:08ed48f1de7f 1 /** \addtogroup hal */
AnnaBridge 185:08ed48f1de7f 2 /** @{*/
AnnaBridge 185:08ed48f1de7f 3 /* mbed Microcontroller Library
AnnaBridge 185:08ed48f1de7f 4 * Copyright (c) 2006-2017 ARM Limited
AnnaBridge 185:08ed48f1de7f 5 *
AnnaBridge 185:08ed48f1de7f 6 * Licensed under the Apache License, Version 2.0 (the "License");
AnnaBridge 185:08ed48f1de7f 7 * you may not use this file except in compliance with the License.
AnnaBridge 185:08ed48f1de7f 8 * You may obtain a copy of the License at
AnnaBridge 185:08ed48f1de7f 9 *
AnnaBridge 185:08ed48f1de7f 10 * http://www.apache.org/licenses/LICENSE-2.0
AnnaBridge 185:08ed48f1de7f 11 *
AnnaBridge 185:08ed48f1de7f 12 * Unless required by applicable law or agreed to in writing, software
AnnaBridge 185:08ed48f1de7f 13 * distributed under the License is distributed on an "AS IS" BASIS,
AnnaBridge 185:08ed48f1de7f 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
AnnaBridge 185:08ed48f1de7f 15 * See the License for the specific language governing permissions and
AnnaBridge 185:08ed48f1de7f 16 * limitations under the License.
AnnaBridge 185:08ed48f1de7f 17 */
AnnaBridge 185:08ed48f1de7f 18 #ifndef MBED_CRITICAL_SECTION_API_H
AnnaBridge 185:08ed48f1de7f 19 #define MBED_CRITICAL_SECTION_API_H
AnnaBridge 185:08ed48f1de7f 20
AnnaBridge 185:08ed48f1de7f 21 #include <stdbool.h>
AnnaBridge 185:08ed48f1de7f 22
AnnaBridge 185:08ed48f1de7f 23 #ifdef __cplusplus
AnnaBridge 185:08ed48f1de7f 24 extern "C" {
AnnaBridge 185:08ed48f1de7f 25 #endif
AnnaBridge 185:08ed48f1de7f 26
AnnaBridge 185:08ed48f1de7f 27 /**
AnnaBridge 185:08ed48f1de7f 28 * \defgroup hal_critical Critical Section HAL functions
AnnaBridge 185:08ed48f1de7f 29 * @{
AnnaBridge 185:08ed48f1de7f 30 */
AnnaBridge 185:08ed48f1de7f 31
AnnaBridge 185:08ed48f1de7f 32 /**
AnnaBridge 185:08ed48f1de7f 33 * Mark the start of a critical section
AnnaBridge 185:08ed48f1de7f 34 *
AnnaBridge 185:08ed48f1de7f 35 * This function will be called by core_util_critical_section_enter() each time
AnnaBridge 185:08ed48f1de7f 36 * the application requests to enter a critical section. The purpose of the
AnnaBridge 185:08ed48f1de7f 37 * critical section is to ensure mutual-exclusion synchronisation of the
AnnaBridge 185:08ed48f1de7f 38 * processor by preventing any change in processor control, the default
AnnaBridge 185:08ed48f1de7f 39 * behaviour requires storing the state of interrupts in the system before
AnnaBridge 185:08ed48f1de7f 40 * disabling them.
AnnaBridge 185:08ed48f1de7f 41 *
AnnaBridge 185:08ed48f1de7f 42 * The critical section code supports nesting. When a thread has entered a
AnnaBridge 185:08ed48f1de7f 43 * critical section it can make additional calls to
AnnaBridge 185:08ed48f1de7f 44 * core_util_critical_section_enter() without deadlocking itself. The critical
AnnaBridge 185:08ed48f1de7f 45 * section driver API tracks the number of nested calls to the critical section.
AnnaBridge 185:08ed48f1de7f 46 * The critical section will only be exited when
AnnaBridge 185:08ed48f1de7f 47 * core_util_critical_section_exit() has been called once for each time it
AnnaBridge 185:08ed48f1de7f 48 * entered the critical section.
AnnaBridge 185:08ed48f1de7f 49 *
AnnaBridge 185:08ed48f1de7f 50 * On the first call to enter a critical section this function MUST store the
AnnaBridge 185:08ed48f1de7f 51 * state of any interrupts or other application settings it will modify to
AnnaBridge 185:08ed48f1de7f 52 * facilitate the critical section.
AnnaBridge 185:08ed48f1de7f 53 *
AnnaBridge 185:08ed48f1de7f 54 * Each successive call to enter the critical section MUST ignore storing or
AnnaBridge 185:08ed48f1de7f 55 * modifying any application state.
AnnaBridge 185:08ed48f1de7f 56 *
AnnaBridge 185:08ed48f1de7f 57 * The default implementation of this function which will save the current state
AnnaBridge 185:08ed48f1de7f 58 * of interrupts before disabling them. This implementation can be found in
AnnaBridge 185:08ed48f1de7f 59 * mbed_critical_section_api.c. This behaviour is can be overridden on a per
AnnaBridge 185:08ed48f1de7f 60 * platform basis by providing a different implementation within the correct
AnnaBridge 185:08ed48f1de7f 61 * targets directory.
AnnaBridge 185:08ed48f1de7f 62 */
AnnaBridge 185:08ed48f1de7f 63 void hal_critical_section_enter(void);
AnnaBridge 185:08ed48f1de7f 64
AnnaBridge 185:08ed48f1de7f 65
AnnaBridge 185:08ed48f1de7f 66 /** Mark the end of a critical section.
AnnaBridge 185:08ed48f1de7f 67 *
AnnaBridge 185:08ed48f1de7f 68 * The purpose of this function is to restore any state that was modified upon
AnnaBridge 185:08ed48f1de7f 69 * entering the critical section, allowing other threads or interrupts to change
AnnaBridge 185:08ed48f1de7f 70 * the processor control.
AnnaBridge 185:08ed48f1de7f 71 *
AnnaBridge 185:08ed48f1de7f 72 * This function will be called once by core_util_critical_section_exit() per
AnnaBridge 185:08ed48f1de7f 73 * critical section on last call to exit. When called, the application MUST
AnnaBridge 185:08ed48f1de7f 74 * restore the saved interrupt/application state that was saved when entering
AnnaBridge 185:08ed48f1de7f 75 * the critical section.
AnnaBridge 185:08ed48f1de7f 76 *
AnnaBridge 185:08ed48f1de7f 77 * There is a default implementation of this function, it will restore the state
AnnaBridge 185:08ed48f1de7f 78 * of interrupts that were previously saved when hal_critical_section_enter was
AnnaBridge 185:08ed48f1de7f 79 * first called, this implementation can be found in
AnnaBridge 185:08ed48f1de7f 80 * mbed_critical_section_api.c. This behaviour is overridable by providing a
AnnaBridge 185:08ed48f1de7f 81 * different function implementation within the correct targets directory.
AnnaBridge 185:08ed48f1de7f 82 */
AnnaBridge 185:08ed48f1de7f 83 void hal_critical_section_exit(void);
AnnaBridge 185:08ed48f1de7f 84
AnnaBridge 185:08ed48f1de7f 85
AnnaBridge 185:08ed48f1de7f 86 /** Determine if the application is currently running in a critical section
AnnaBridge 185:08ed48f1de7f 87 *
AnnaBridge 185:08ed48f1de7f 88 * The purpose of this function is to inform the caller whether or not the
AnnaBridge 185:08ed48f1de7f 89 * application is running in a critical section. This is done by checking if
AnnaBridge 185:08ed48f1de7f 90 * the current interrupt state has been saved in the underlying implementation,
AnnaBridge 185:08ed48f1de7f 91 * this could also be done by checking the state of the interrupts at the time
AnnaBridge 185:08ed48f1de7f 92 * of calling.
AnnaBridge 185:08ed48f1de7f 93 *
AnnaBridge 185:08ed48f1de7f 94 * @return True if running in a critical section, false if not.
AnnaBridge 185:08ed48f1de7f 95 */
AnnaBridge 185:08ed48f1de7f 96 bool hal_in_critical_section(void);
AnnaBridge 185:08ed48f1de7f 97
AnnaBridge 185:08ed48f1de7f 98
AnnaBridge 185:08ed48f1de7f 99 /**@}*/
AnnaBridge 185:08ed48f1de7f 100
AnnaBridge 185:08ed48f1de7f 101 #ifdef __cplusplus
AnnaBridge 185:08ed48f1de7f 102 }
AnnaBridge 185:08ed48f1de7f 103 #endif
AnnaBridge 185:08ed48f1de7f 104
AnnaBridge 185:08ed48f1de7f 105 #endif // MBED_CRITICAL_SECTION_API_H
AnnaBridge 185:08ed48f1de7f 106
AnnaBridge 185:08ed48f1de7f 107 /** @}*/