RTC auf true
platform/mbed_critical.h
- Committer:
- kevman
- Date:
- 2018-11-28
- Revision:
- 0:38ceb79fef03
File content as of revision 0:38ceb79fef03:
/* * Copyright (c) 2015-2016, ARM Limited, All Rights Reserved * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifndef __MBED_UTIL_CRITICAL_H__ #define __MBED_UTIL_CRITICAL_H__ #include <stdbool.h> #include <stdint.h> #include <stddef.h> #ifdef __cplusplus extern "C" { #endif /** \addtogroup platform */ /** @{*/ /** * \defgroup platform_critical critical section function * @{ */ /** Determine the current interrupts enabled state * * This function can be called to determine whether or not interrupts are currently enabled. * @note * NOTE: * This function works for both cortex-A and cortex-M, although the underlying implementation * differs. * @return true if interrupts are enabled, false otherwise */ bool core_util_are_interrupts_enabled(void); /** Determine if this code is executing from an interrupt * * This function can be called to determine if the code is running on interrupt context. * @note * NOTE: * This function works for both cortex-A and cortex-M, although the underlying implementation * differs. * @return true if in an isr, false otherwise */ bool core_util_is_isr_active(void); /** Mark the start of a critical section * * This function should be called to mark the start of a critical section of code. * @note * NOTES: * 1) The use of this style of critical section is targetted at C based implementations. * 2) These critical sections can be nested. * 3) The interrupt enable state on entry to the first critical section (of a nested set, or single * section) will be preserved on exit from the section. * 4) This implementation will currently only work on code running in privileged mode. */ void core_util_critical_section_enter(void); /** Mark the end of a critical section * * This function should be called to mark the end of a critical section of code. * @note * NOTES: * 1) The use of this style of critical section is targetted at C based implementations. * 2) These critical sections can be nested. * 3) The interrupt enable state on entry to the first critical section (of a nested set, or single * section) will be preserved on exit from the section. * 4) This implementation will currently only work on code running in privileged mode. */ void core_util_critical_section_exit(void); /** * Determine if we are currently in a critical section * * @return true if in a critical section, false otherwise. */ bool core_util_in_critical_section(void); /** * Atomic compare and set. It compares the contents of a memory location to a * given value and, only if they are the same, modifies the contents of that * memory location to a given new value. This is done as a single atomic * operation. The atomicity guarantees that the new value is calculated based on * up-to-date information; if the value had been updated by another thread in * the meantime, the write would fail due to a mismatched expectedCurrentValue. * * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect * you to the article on compare-and swap]. * * @param ptr The target memory location. * @param[in,out] expectedCurrentValue A pointer to some location holding the * expected current value of the data being set atomically. * The computed 'desiredValue' should be a function of this current value. * @note: This is an in-out parameter. In the * failure case of atomic_cas (where the * destination isn't set), the pointee of expectedCurrentValue is * updated with the current value. * @param[in] desiredValue The new value computed based on '*expectedCurrentValue'. * * @return true if the memory location was atomically * updated with the desired value (after verifying * that it contained the expectedCurrentValue), * false otherwise. In the failure case, * exepctedCurrentValue is updated with the new * value of the target memory location. * * pseudocode: * function cas(p : pointer to int, old : pointer to int, new : int) returns bool { * if *p != *old { * *old = *p * return false * } * *p = new * return true * } * * @note: In the failure case (where the destination isn't set), the value * pointed to by expectedCurrentValue is instead updated with the current value. * This property helps writing concise code for the following incr: * * function incr(p : pointer to int, a : int) returns int { * done = false * value = *p // This fetch operation need not be atomic. * while not done { * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success * } * return value + a * } * * @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it * always succeeds if the current value is expected, as per the pseudocode * above; it will not spuriously fail as "atomic_compare_exchange_weak" may. */ bool core_util_atomic_cas_u8(volatile uint8_t *ptr, uint8_t *expectedCurrentValue, uint8_t desiredValue); /** * Atomic compare and set. It compares the contents of a memory location to a * given value and, only if they are the same, modifies the contents of that * memory location to a given new value. This is done as a single atomic * operation. The atomicity guarantees that the new value is calculated based on * up-to-date information; if the value had been updated by another thread in * the meantime, the write would fail due to a mismatched expectedCurrentValue. * * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect * you to the article on compare-and swap]. * * @param ptr The target memory location. * @param[in,out] expectedCurrentValue A pointer to some location holding the * expected current value of the data being set atomically. * The computed 'desiredValue' should be a function of this current value. * @note: This is an in-out parameter. In the * failure case of atomic_cas (where the * destination isn't set), the pointee of expectedCurrentValue is * updated with the current value. * @param[in] desiredValue The new value computed based on '*expectedCurrentValue'. * * @return true if the memory location was atomically * updated with the desired value (after verifying * that it contained the expectedCurrentValue), * false otherwise. In the failure case, * exepctedCurrentValue is updated with the new * value of the target memory location. * * pseudocode: * function cas(p : pointer to int, old : pointer to int, new : int) returns bool { * if *p != *old { * *old = *p * return false * } * *p = new * return true * } * * @note: In the failure case (where the destination isn't set), the value * pointed to by expectedCurrentValue is instead updated with the current value. * This property helps writing concise code for the following incr: * * function incr(p : pointer to int, a : int) returns int { * done = false * value = *p // This fetch operation need not be atomic. * while not done { * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success * } * return value + a * } * * @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it * always succeeds if the current value is expected, as per the pseudocode * above; it will not spuriously fail as "atomic_compare_exchange_weak" may. */ bool core_util_atomic_cas_u16(volatile uint16_t *ptr, uint16_t *expectedCurrentValue, uint16_t desiredValue); /** * Atomic compare and set. It compares the contents of a memory location to a * given value and, only if they are the same, modifies the contents of that * memory location to a given new value. This is done as a single atomic * operation. The atomicity guarantees that the new value is calculated based on * up-to-date information; if the value had been updated by another thread in * the meantime, the write would fail due to a mismatched expectedCurrentValue. * * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect * you to the article on compare-and swap]. * * @param ptr The target memory location. * @param[in,out] expectedCurrentValue A pointer to some location holding the * expected current value of the data being set atomically. * The computed 'desiredValue' should be a function of this current value. * @note: This is an in-out parameter. In the * failure case of atomic_cas (where the * destination isn't set), the pointee of expectedCurrentValue is * updated with the current value. * @param[in] desiredValue The new value computed based on '*expectedCurrentValue'. * * @return true if the memory location was atomically * updated with the desired value (after verifying * that it contained the expectedCurrentValue), * false otherwise. In the failure case, * exepctedCurrentValue is updated with the new * value of the target memory location. * * pseudocode: * function cas(p : pointer to int, old : pointer to int, new : int) returns bool { * if *p != *old { * *old = *p * return false * } * *p = new * return true * } * * @note: In the failure case (where the destination isn't set), the value * pointed to by expectedCurrentValue is instead updated with the current value. * This property helps writing concise code for the following incr: * * function incr(p : pointer to int, a : int) returns int { * done = false * value = *p // This fetch operation need not be atomic. * while not done { * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success * } * return value + a * * @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it * always succeeds if the current value is expected, as per the pseudocode * above; it will not spuriously fail as "atomic_compare_exchange_weak" may. * } */ bool core_util_atomic_cas_u32(volatile uint32_t *ptr, uint32_t *expectedCurrentValue, uint32_t desiredValue); /** * Atomic compare and set. It compares the contents of a memory location to a * given value and, only if they are the same, modifies the contents of that * memory location to a given new value. This is done as a single atomic * operation. The atomicity guarantees that the new value is calculated based on * up-to-date information; if the value had been updated by another thread in * the meantime, the write would fail due to a mismatched expectedCurrentValue. * * Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect * you to the article on compare-and swap]. * * @param ptr The target memory location. * @param[in,out] expectedCurrentValue A pointer to some location holding the * expected current value of the data being set atomically. * The computed 'desiredValue' should be a function of this current value. * @note: This is an in-out parameter. In the * failure case of atomic_cas (where the * destination isn't set), the pointee of expectedCurrentValue is * updated with the current value. * @param[in] desiredValue The new value computed based on '*expectedCurrentValue'. * * @return true if the memory location was atomically * updated with the desired value (after verifying * that it contained the expectedCurrentValue), * false otherwise. In the failure case, * exepctedCurrentValue is updated with the new * value of the target memory location. * * pseudocode: * function cas(p : pointer to int, old : pointer to int, new : int) returns bool { * if *p != *old { * *old = *p * return false * } * *p = new * return true * } * * @note: In the failure case (where the destination isn't set), the value * pointed to by expectedCurrentValue is instead updated with the current value. * This property helps writing concise code for the following incr: * * function incr(p : pointer to int, a : int) returns int { * done = false * value = *p // This fetch operation need not be atomic. * while not done { * done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success * } * return value + a * } * * @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it * always succeeds if the current value is expected, as per the pseudocode * above; it will not spuriously fail as "atomic_compare_exchange_weak" may. */ bool core_util_atomic_cas_ptr(void *volatile *ptr, void **expectedCurrentValue, void *desiredValue); /** * Atomic increment. * @param valuePtr Target memory location being incremented. * @param delta The amount being incremented. * @return The new incremented value. */ uint8_t core_util_atomic_incr_u8(volatile uint8_t *valuePtr, uint8_t delta); /** * Atomic increment. * @param valuePtr Target memory location being incremented. * @param delta The amount being incremented. * @return The new incremented value. */ uint16_t core_util_atomic_incr_u16(volatile uint16_t *valuePtr, uint16_t delta); /** * Atomic increment. * @param valuePtr Target memory location being incremented. * @param delta The amount being incremented. * @return The new incremented value. */ uint32_t core_util_atomic_incr_u32(volatile uint32_t *valuePtr, uint32_t delta); /** * Atomic increment. * @param valuePtr Target memory location being incremented. * @param delta The amount being incremented in bytes. * @return The new incremented value. * * @note The type of the pointer argument is not taken into account * and the pointer is incremented by bytes. */ void *core_util_atomic_incr_ptr(void *volatile *valuePtr, ptrdiff_t delta); /** * Atomic decrement. * @param valuePtr Target memory location being decremented. * @param delta The amount being decremented. * @return The new decremented value. */ uint8_t core_util_atomic_decr_u8(volatile uint8_t *valuePtr, uint8_t delta); /** * Atomic decrement. * @param valuePtr Target memory location being decremented. * @param delta The amount being decremented. * @return The new decremented value. */ uint16_t core_util_atomic_decr_u16(volatile uint16_t *valuePtr, uint16_t delta); /** * Atomic decrement. * @param valuePtr Target memory location being decremented. * @param delta The amount being decremented. * @return The new decremented value. */ uint32_t core_util_atomic_decr_u32(volatile uint32_t *valuePtr, uint32_t delta); /** * Atomic decrement. * @param valuePtr Target memory location being decremented. * @param delta The amount being decremented in bytes. * @return The new decremented value. * * @note The type of the pointer argument is not taken into account * and the pointer is decremented by bytes */ void *core_util_atomic_decr_ptr(void *volatile *valuePtr, ptrdiff_t delta); #ifdef __cplusplus } // extern "C" #endif /**@}*/ /**@}*/ #endif // __MBED_UTIL_CRITICAL_H__