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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