[352] | 1 | /* mbed Microcontroller Library
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| 2 | * Copyright (c) 2006-2013 ARM Limited
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| 3 | *
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| 4 | * Licensed under the Apache License, Version 2.0 (the "License");
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| 5 | * you may not use this file except in compliance with the License.
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| 6 | * You may obtain a copy of the License at
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| 7 | *
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| 8 | * http://www.apache.org/licenses/LICENSE-2.0
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| 9 | *
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| 10 | * Unless required by applicable law or agreed to in writing, software
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| 11 | * distributed under the License is distributed on an "AS IS" BASIS,
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| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 13 | * See the License for the specific language governing permissions and
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| 14 | * limitations under the License.
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| 15 | */
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[374] | 16 |
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| 17 | /** \addtogroup hal */
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| 18 | /** @{*/
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| 19 |
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[352] | 20 | #ifndef MBED_RTC_API_H
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| 21 | #define MBED_RTC_API_H
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| 22 |
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| 23 | #include "device.h"
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| 24 |
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| 25 | #include <time.h>
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| 26 |
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| 27 | #ifdef __cplusplus
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| 28 | extern "C" {
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| 29 | #endif
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| 30 |
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| 31 | /**
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[374] | 32 | * \defgroup hal_rtc RTC hal
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| 33 | *
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| 34 | * The RTC hal provides a low level interface to the Real Time Counter (RTC) of a
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| 35 | * target.
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| 36 | *
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| 37 | * # Defined behaviour
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| 38 | * * The function ::rtc_init is safe to call repeatedly - Verified by test ::rtc_init_test.
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| 39 | * * RTC accuracy is at least 10% - Verified by test ::rtc_accuracy_test.
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| 40 | * * Init/free doesn't stop RTC from counting - Verified by test ::rtc_persist_test.
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| 41 | * * Software reset doesn't stop RTC from counting - Verified by test ::rtc_reset_test.
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| 42 | * * Sleep modes don't stop RTC from counting - Verified by test ::rtc_sleep_test.
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| 43 | * * Shutdown mode doesn't stop RTC from counting - Not verified.
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| 44 | * * The functions ::rtc_write/::rtc_read provides availability to set/get RTC time
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| 45 | * - Verified by test ::rtc_write_read_test.
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| 46 | * * The functions ::rtc_isenabled returns 1 if the RTC is counting and the time has been set,
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| 47 | * 0 otherwise - Verified by test ::rtc_enabled_test.
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| 48 | *
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| 49 | * # Undefined behaviour
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| 50 | * * Calling any function other than ::rtc_init before the initialisation of the RTC
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| 51 | *
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| 52 | * # Potential bugs
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| 53 | * * Incorrect overflow handling - Verified by ::rtc_range_test
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| 54 | * * Glitches due to ripple counter - Verified by ::rtc_glitch_test
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| 55 | *
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| 56 | * @see hal_rtc_tests
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| 57 | *
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[352] | 58 | * @{
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| 59 | */
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| 60 |
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[374] | 61 | /**
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| 62 | * \defgroup hal_rtc_tests RTC hal tests
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| 63 | * The RTC test validate proper implementation of the RTC hal.
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| 64 | *
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| 65 | * To run the RTC hal tests use the command:
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| 66 | *
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| 67 | * mbed test -t <toolchain> -m <target> -n tests-mbed_hal-rtc*
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| 68 | */
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| 69 |
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| 70 |
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[352] | 71 | /** Initialize the RTC peripheral
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| 72 | *
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[374] | 73 | * Powerup the RTC in perpetration for access. This function must be called
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| 74 | * before any other RTC functions ares called. This does not change the state
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| 75 | * of the RTC. It just enables access to it.
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| 76 | *
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| 77 | * @note This function is safe to call repeatedly - Tested by ::rtc_init_test
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| 78 | *
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| 79 | * Example Implementation Pseudo Code:
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| 80 | * @code
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| 81 | * void rtc_init()
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| 82 | * {
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| 83 | * // Enable clock gate so processor can read RTC registers
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| 84 | * POWER_CTRL |= POWER_CTRL_RTC_Msk;
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| 85 | *
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| 86 | * // See if the RTC is already setup
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| 87 | * if (!(RTC_STATUS & RTC_STATUS_COUNTING_Msk)) {
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| 88 | *
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| 89 | * // Setup the RTC clock source
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| 90 | * RTC_CTRL |= RTC_CTRL_CLK32_Msk;
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| 91 | * }
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| 92 | * }
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| 93 | * @endcode
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[352] | 94 | */
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| 95 | void rtc_init(void);
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| 96 |
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| 97 | /** Deinitialize RTC
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| 98 | *
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[374] | 99 | * Powerdown the RTC in preparation for sleep, powerdown or reset. That should only
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| 100 | * affect the CPU domain and not the time keeping logic.
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| 101 | * After this function is called no other RTC functions should be called
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| 102 | * except for ::rtc_init.
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| 103 | *
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| 104 | * @note This function does not stop the RTC from counting - Tested by ::rtc_persist_test
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| 105 | *
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| 106 | * Example Implementation Pseudo Code:
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| 107 | * @code
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| 108 | * void rtc_free()
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| 109 | * {
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| 110 | * // Disable clock gate since processor no longer needs to read RTC registers
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| 111 | * POWER_CTRL &= ~POWER_CTRL_RTC_Msk;
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| 112 | * }
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| 113 | * @endcode
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[352] | 114 | */
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| 115 | void rtc_free(void);
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| 116 |
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[374] | 117 | /** Check if the RTC has the time set and is counting
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[352] | 118 | *
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[374] | 119 | * @retval 0 The time reported by the RTC is not valid
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| 120 | * @retval 1 The time has been set the RTC is counting
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| 121 | *
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| 122 | * Example Implementation Pseudo Code:
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| 123 | * @code
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| 124 | * int rtc_isenabled()
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| 125 | * {
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| 126 | * if (RTC_STATUS & RTC_STATUS_COUNTING_Msk) {
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| 127 | * return 1;
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| 128 | * } else {
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| 129 | * return 0;
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| 130 | * }
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| 131 | * }
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| 132 | * @endcode
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[352] | 133 | */
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| 134 | int rtc_isenabled(void);
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| 135 |
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| 136 | /** Get the current time from the RTC peripheral
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| 137 | *
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[374] | 138 | * @return The current time in seconds
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| 139 | *
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| 140 | * @note Some RTCs are not synchronized with the main clock. If
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| 141 | * this is the case with your RTC then you must read the RTC time
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| 142 | * in a loop to prevent reading the wrong time due to a glitch.
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| 143 | * The test ::rtc_glitch_test is intended to catch this bug.
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| 144 | *
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| 145 | * Example implementation for an unsynchronized ripple counter:
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| 146 | * @code
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| 147 | * time_t rtc_read()
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| 148 | * {
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| 149 | * uint32_t val;
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| 150 | * uint32_t last_val;
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| 151 | *
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| 152 | * // Loop until the same value is read twice
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| 153 | * val = RTC_SECONDS;
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| 154 | * do {
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| 155 | * last_val = val;
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| 156 | * val = RTC_SECONDS;
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| 157 | * } while (last_val != val);
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| 158 | *
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| 159 | * return (time_t)val;
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| 160 | * }
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| 161 | * @endcode
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[352] | 162 | */
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| 163 | time_t rtc_read(void);
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| 164 |
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[374] | 165 | /** Write the current time in seconds to the RTC peripheral
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[352] | 166 | *
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[374] | 167 | * @param t The current time to be set in seconds.
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| 168 | *
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| 169 | * Example Implementation Pseudo Code:
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| 170 | * @code
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| 171 | * void rtc_write(time_t t)
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| 172 | * {
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| 173 | * RTC_SECONDS = t;
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| 174 | * }
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| 175 | * @endcode
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[352] | 176 | */
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| 177 | void rtc_write(time_t t);
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| 178 |
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| 179 | /**@}*/
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| 180 |
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| 181 | #ifdef __cplusplus
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| 182 | }
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| 183 | #endif
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| 184 |
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| 185 | #endif
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| 186 |
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| 187 | /** @}*/
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