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clemtaylor/app_timer.c

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app_timer with PPI/TIMER based overflow counter
Raw
app_timer.c
/* Copyright (c) 2012 Nordic Semiconductor. All Rights Reserved.
*
* The information contained herein is property of Nordic Semiconductor ASA.
* Terms and conditions of usage are described in detail in NORDIC
* SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
*
* Licensees are granted free, non-transferable use of the information. NO
* WARRANTY of ANY KIND is provided. This heading must NOT be removed from
* the file.
*
*/
#include "app_timer.h"
#include <stdlib.h>
#include "nrf51.h"
#include "nrf51_bitfields.h"
#include "nrf_soc.h"
#include "app_error.h"
#include "nrf_delay.h"
#include "app_util.h"
#include "app_util_platform.h"
#define RTC1_IRQ_PRI APP_IRQ_PRIORITY_LOW /**< Priority of the RTC1 interrupt (used for checking for timeouts and executing timeout handlers). */
#define SWI0_IRQ_PRI APP_IRQ_PRIORITY_LOW /**< Priority of the SWI0 interrupt (used for updating the timer list). */
// The current design assumes that both interrupt handlers run at the same interrupt level.
// If this is to be changed, protection must be added to prevent them from interrupting each other
// (e.g. by using guard/trigger flags).
STATIC_ASSERT(RTC1_IRQ_PRI == SWI0_IRQ_PRI);
#define MAX_RTC_COUNTER_VAL 0x00FFFFFF /**< Maximum value of the RTC counter. */
#define APP_HIGH_USER_ID 0 /**< User Id for the Application High "user". */
#define APP_LOW_USER_ID 1 /**< User Id for the Application Low "user". */
#define THREAD_MODE_USER_ID 2 /**< User Id for the Thread Mode "user". */
#define RTC_COMPARE_OFFSET_MIN 3 /**< Minimum offset between the current RTC counter value and the Capture Compare register. Although the nRF51 Series User Specification recommends this value to be 2, we use 3 to be safer.*/
#define MAX_RTC_TASKS_DELAY 47 /**< Maximum delay until an RTC task is executed. */
/**@brief Timer allocation state type. */
typedef enum
{
STATE_FREE, /**< The timer node is available. */
STATE_ALLOCATED /**< The timer node has been allocated. */
} timer_alloc_state_t;
/**@brief Timer node type. The nodes will be used form a linked list of running timers. */
typedef struct
{
timer_alloc_state_t state; /**< Timer allocation state. */
app_timer_mode_t mode; /**< Timer mode. */
bool is_running; /**< True if timer is running, False otherwise. */
uint32_t ticks_to_expire; /**< Number of ticks from previous timer interrupt to timer expiry. */
uint32_t ticks_at_start; /**< Current RTC counter value when the timer was started. */
uint32_t ticks_first_interval; /**< Number of ticks in the first timer interval. */
uint32_t ticks_periodic_interval; /**< Timer period (for repeating timers). */
app_timer_timeout_handler_t p_timeout_handler; /**< Pointer to function to be executed when the timer expires. */
void * p_context; /**< General purpose pointer. Will be passed to the timeout handler when the timer expires. */
app_timer_id_t next; /**< Id of next timer in list of running timers. */
} timer_node_t;
STATIC_ASSERT(sizeof(timer_node_t) <= APP_TIMER_NODE_SIZE);
STATIC_ASSERT(sizeof(timer_node_t) % 4 == 0);
/**@brief Set of available timer operation types. */
typedef enum
{
TIMER_USER_OP_TYPE_NONE, /**< Invalid timer operation type. */
TIMER_USER_OP_TYPE_START, /**< Timer operation type Start. */
TIMER_USER_OP_TYPE_STOP, /**< Timer operation type Stop. */
TIMER_USER_OP_TYPE_STOP_ALL /**< Timer operation type Stop All. */
} timer_user_op_type_t;
/**@brief Structure describing a timer start operation. */
typedef struct
{
uint32_t ticks_at_start; /**< Current RTC counter value when the timer was started. */
uint32_t ticks_first_interval; /**< Number of ticks in the first timer interval. */
uint32_t ticks_periodic_interval; /**< Timer period (for repeating timers). */
void * p_context; /**< General purpose pointer. Will be passed to the timeout handler when the timer expires. */
} timer_user_op_start_t;
/**@brief Structure describing a timer operation. */
typedef struct
{
timer_user_op_type_t op_type; /**< Timer operation type. */
app_timer_id_t timer_id; /**< Id of timer on which the operation is to be performed. */
union
{
timer_user_op_start_t start; /**< Structure describing a timer start operation. */
} params;
} timer_user_op_t;
STATIC_ASSERT(sizeof(timer_user_op_t) <= APP_TIMER_USER_OP_SIZE);
STATIC_ASSERT(sizeof(timer_user_op_t) % 4 == 0);
/**@brief Structure describing a timer user.
*
* @details For each user of the timer module, there will be a timer operations queue. This queue
* will hold timer operations issued by this user until the timer interrupt handler
* processes these operations. For the current implementation, there will be one user for
* each interrupt level available to the application (APP_HIGH, APP_LOW and THREAD_MODE),
* but the module can easily be modified to e.g. have one queue per process when using an
* RTOS. The purpose of the queues is to be able to have a completely lockless timer
* implementation.
*/
typedef struct
{
uint8_t first; /**< Index of first entry to have been inserted in the queue (i.e. the next entry to be executed). */
uint8_t last; /**< Index of last entry to have been inserted in the queue. */
uint8_t user_op_queue_size; /**< Queue size. */
timer_user_op_t * p_user_op_queue; /**< Queue buffer. */
} timer_user_t;
STATIC_ASSERT(sizeof(timer_user_t) == APP_TIMER_USER_SIZE);
STATIC_ASSERT(sizeof(timer_user_t) % 4 == 0);
/**@brief User id type.
*
* @details In the current implementation, this will automatically be generated from the current
* interrupt level.
*/
typedef uint32_t timer_user_id_t;
#define TIMER_NULL ((app_timer_id_t)(0 - 1)) /**< Invalid timer id. */
#define CONTEXT_QUEUE_SIZE_MAX (2) /**< Timer internal elapsed ticks queue size. */
static uint8_t m_node_array_size; /**< Size of timer node array. */
static timer_node_t * mp_nodes = NULL; /**< Array of timer nodes. */
static uint8_t m_user_array_size; /**< Size of timer user array. */
static timer_user_t * mp_users; /**< Array of timer users. */
static app_timer_id_t m_timer_id_head; /**< First timer in list of running timers. */
static uint32_t m_ticks_latest; /**< Last known RTC counter value. */
static uint32_t m_ticks_elapsed[CONTEXT_QUEUE_SIZE_MAX]; /**< Timer internal elapsed ticks queue. */
static uint8_t m_ticks_elapsed_q_read_ind; /**< Timer internal elapsed ticks queue read index. */
static uint8_t m_ticks_elapsed_q_write_ind; /**< Timer internal elapsed ticks queue write index. */
static app_timer_evt_schedule_func_t m_evt_schedule_func; /**< Pointer to function for propagating timeout events to the scheduler. */
static bool m_rtc1_running; /**< Boolean indicating if RTC1 is running. */
static bool m_rtc1_reset; /**< Boolean indicating if RTC1 counter has been reset due to last timer removed from timer list during the timer list handling. */
/**@brief Function for initializing the RTC1 counter.
*
* @param[in] prescaler Value of the RTC1 PRESCALER register. Set to 0 for no prescaling.
*/
static void rtc1_init(uint32_t prescaler)
{
NRF_RTC1->PRESCALER = prescaler;
NVIC_SetPriority(RTC1_IRQn, RTC1_IRQ_PRI);
}
/**@brief Function for starting the RTC1 timer.
*/
static void rtc1_start(void)
{
NRF_RTC1->EVTENSET = RTC_EVTEN_COMPARE0_Msk | RTC_EVTEN_OVRFLW_Msk;
NRF_RTC1->INTENSET = RTC_INTENSET_COMPARE0_Msk;
NVIC_ClearPendingIRQ(RTC1_IRQn);
NVIC_EnableIRQ(RTC1_IRQn);
NRF_RTC1->TASKS_START = 1;
nrf_delay_us(MAX_RTC_TASKS_DELAY);
m_rtc1_running = true;
}
/**@brief Function for stopping the RTC1 timer.
*/
static void rtc1_stop(void)
{
NVIC_DisableIRQ(RTC1_IRQn);
NRF_RTC1->EVTENCLR = -1; // clear everything
NRF_RTC1->INTENCLR = -1; // clear everything
NRF_RTC1->TASKS_STOP = 1;
nrf_delay_us(MAX_RTC_TASKS_DELAY);
NRF_RTC1->TASKS_CLEAR = 1;
m_ticks_latest = 0;
nrf_delay_us(MAX_RTC_TASKS_DELAY);
m_rtc1_running = false;
}
/**@brief Function for returning the current value of the RTC1 counter.
*
* @return Current value of the RTC1 counter.
*/
static __INLINE uint32_t rtc1_counter_get(void)
{
return NRF_RTC1->COUNTER;
}
/**@brief Function for computing the difference between two RTC1 counter values.
*
* @return Number of ticks elapsed from ticks_old to ticks_now.
*/
static __INLINE uint32_t ticks_diff_get(uint32_t ticks_now, uint32_t ticks_old)
{
return ((ticks_now - ticks_old) & MAX_RTC_COUNTER_VAL);
}
/**@brief Function for setting the RTC1 Capture Compare register 0, and enabling the corresponding
* event.
*
* @param[in] value New value of Capture Compare register 0.
*/
static __INLINE void rtc1_compare0_set(uint32_t value)
{
NRF_RTC1->CC[0] = value;
}
/**@brief Function for inserting a timer in the timer list.
*
* @param[in] timer_id Id of timer to insert.
*/
static void timer_list_insert(app_timer_id_t timer_id)
{
timer_node_t * p_timer = &mp_nodes[timer_id];
if (m_timer_id_head == TIMER_NULL)
{
m_timer_id_head = timer_id;
}
else
{
if (p_timer->ticks_to_expire <= mp_nodes[m_timer_id_head].ticks_to_expire)
{
mp_nodes[m_timer_id_head].ticks_to_expire -= p_timer->ticks_to_expire;
p_timer->next = m_timer_id_head;
m_timer_id_head = timer_id;
}
else
{
app_timer_id_t previous;
app_timer_id_t current;
uint32_t ticks_to_expire;
ticks_to_expire = p_timer->ticks_to_expire;
previous = m_timer_id_head;
current = m_timer_id_head;
while ((current != TIMER_NULL) && (ticks_to_expire > mp_nodes[current].ticks_to_expire))
{
ticks_to_expire -= mp_nodes[current].ticks_to_expire;
previous = current;
current = mp_nodes[current].next;
}
if (current != TIMER_NULL)
{
mp_nodes[current].ticks_to_expire -= ticks_to_expire;
}
p_timer->ticks_to_expire = ticks_to_expire;
p_timer->next = current;
mp_nodes[previous].next = timer_id;
}
}
}
/**@brief Function for removing a timer from the timer queue.
*
* @param[in] timer_id Id of timer to remove.
*/
static void timer_list_remove(app_timer_id_t timer_id)
{
app_timer_id_t previous;
app_timer_id_t current;
uint32_t timeout;
// Find the timer's position in timer list.
previous = m_timer_id_head;
current = previous;
while (current != TIMER_NULL)
{
if (current == timer_id)
{
break;
}
previous = current;
current = mp_nodes[current].next;
}
// Timer not in active list.
if (current == TIMER_NULL)
{
return;
}
// Timer is the first in the list
if (previous == current)
{
m_timer_id_head = mp_nodes[m_timer_id_head].next;
// No more timers in the list. Reset RTC1 in case Start timer operations are present in the queue.
if (m_timer_id_head == TIMER_NULL)
{
NRF_RTC1->TASKS_CLEAR = 1;
m_ticks_latest = 0;
m_rtc1_reset = true;
}
}
// Remaining timeout between next timeout.
timeout = mp_nodes[current].ticks_to_expire;
// Link previous timer with next of this timer, i.e. removing the timer from list.
mp_nodes[previous].next = mp_nodes[current].next;
// If this is not the last timer, increment the next timer by this timer timeout.
current = mp_nodes[previous].next;
if (current != TIMER_NULL)
{
mp_nodes[current].ticks_to_expire += timeout;
}
}
/**@brief Function for scheduling a check for timeouts by generating a RTC1 interrupt.
*/
static void timer_timeouts_check_sched(void)
{
NVIC_SetPendingIRQ(RTC1_IRQn);
}
/**@brief Function for scheduling a timer list update by generating a SWI0 interrupt.
*/
static void timer_list_handler_sched(void)
{
NVIC_SetPendingIRQ(SWI0_IRQn);
}
/**@brief Function for executing an application timeout handler, either by calling it directly, or
* by passing an event to the @ref app_scheduler.
*
* @param[in] p_timer Pointer to expired timer.
*/
static void timeout_handler_exec(timer_node_t * p_timer)
{
if (m_evt_schedule_func != NULL)
{
uint32_t err_code = m_evt_schedule_func(p_timer->p_timeout_handler, p_timer->p_context);
APP_ERROR_CHECK(err_code);
}
else
{
p_timer->p_timeout_handler(p_timer->p_context);
}
}
/**@brief Function for checking for expired timers.
*/
static void timer_timeouts_check(void)
{
// Handle expired of timer
if (m_timer_id_head != TIMER_NULL)
{
app_timer_id_t timer_id;
uint32_t ticks_elapsed;
uint32_t ticks_expired;
// Initialize actual elapsed ticks being consumed to 0.
ticks_expired = 0;
// ticks_elapsed is collected here, job will use it.
ticks_elapsed = ticks_diff_get(rtc1_counter_get(), m_ticks_latest);
// Auto variable containing the head of timers expiring.
timer_id = m_timer_id_head;
// Expire all timers within ticks_elapsed and collect ticks_expired.
while (timer_id != TIMER_NULL)
{
timer_node_t * p_timer;
// Auto variable for current timer node
p_timer = &mp_nodes[timer_id];
// Do nothing if timer did not expire.
if (ticks_elapsed < p_timer->ticks_to_expire)
{
break;
}
// Decrement ticks_elapsed and collect expired ticks.
ticks_elapsed -= p_timer->ticks_to_expire;
ticks_expired += p_timer->ticks_to_expire;
// Move to next timer.
timer_id = p_timer->next;
// Execute Task.
timeout_handler_exec(p_timer);
}
// Prepare to queue the ticks expired in the m_ticks_elapsed queue.
if (m_ticks_elapsed_q_read_ind == m_ticks_elapsed_q_write_ind)
{
// The read index of the queue is equal to the write index. This means the new
// value of ticks_expired should be stored at a new location in the m_ticks_elapsed
// queue (which is implemented as a double buffer).
// Check if there will be a queue overflow.
if (++m_ticks_elapsed_q_write_ind == CONTEXT_QUEUE_SIZE_MAX)
{
// There will be a queue overflow. Hence the write index should point to the start
// of the queue.
m_ticks_elapsed_q_write_ind = 0;
}
}
// Queue the ticks expired.
m_ticks_elapsed[m_ticks_elapsed_q_write_ind] = ticks_expired;
timer_list_handler_sched();
}
}
/**@brief Function for acquiring the number of ticks elapsed.
*
* @param[out] p_ticks_elapsed Number of ticks elapsed.
*
* @return TRUE if elapsed ticks was read from queue, FALSE otherwise.
*/
static bool elapsed_ticks_acquire(uint32_t * p_ticks_elapsed)
{
// Pick the elapsed value from queue.
if (m_ticks_elapsed_q_read_ind != m_ticks_elapsed_q_write_ind)
{
// Dequeue elapsed value.
m_ticks_elapsed_q_read_ind++;
if (m_ticks_elapsed_q_read_ind == CONTEXT_QUEUE_SIZE_MAX)
{
m_ticks_elapsed_q_read_ind = 0;
}
*p_ticks_elapsed = m_ticks_elapsed[m_ticks_elapsed_q_read_ind];
m_ticks_latest += *p_ticks_elapsed;
m_ticks_latest &= MAX_RTC_COUNTER_VAL;
return true;
}
else
{
// No elapsed value in queue.
*p_ticks_elapsed = 0;
return false;
}
}
/**@brief Function for handling the timer list deletions.
*
* @return TRUE if Capture Compare register must be updated, FALSE otherwise.
*/
static bool list_deletions_handler(void)
{
app_timer_id_t timer_id_old_head;
uint8_t user_id;
// Remember the old head, so as to decide if new compare needs to be set.
timer_id_old_head = m_timer_id_head;
user_id = m_user_array_size;
while (user_id--)
{
timer_user_t * p_user = &mp_users[user_id];
uint8_t user_ops_first = p_user->first;
while (user_ops_first != p_user->last)
{
timer_node_t * p_timer;
timer_user_op_t * p_user_op = &p_user->p_user_op_queue[user_ops_first];
// Traverse to next operation in queue.
user_ops_first++;
if (user_ops_first == p_user->user_op_queue_size)
{
user_ops_first = 0;
}
switch (p_user_op->op_type)
{
case TIMER_USER_OP_TYPE_STOP:
// Delete node if timer is running.
p_timer = &mp_nodes[p_user_op->timer_id];
if (p_timer->is_running)
{
timer_list_remove(p_user_op->timer_id);
p_timer->is_running = false;
}
break;
case TIMER_USER_OP_TYPE_STOP_ALL:
// Delete list of running timers, and mark all timers as not running.
while (m_timer_id_head != TIMER_NULL)
{
timer_node_t * p_head = &mp_nodes[m_timer_id_head];
p_head->is_running = false;
m_timer_id_head = p_head->next;
}
break;
default:
// No implementation needed.
break;
}
}
}
// Detect change in head of the list.
return (m_timer_id_head != timer_id_old_head);
}
/**@brief Function for updating the timer list for expired timers.
*
* @param[in] ticks_elapsed Number of elapsed ticks.
* @param[in] ticks_previous Previous known value of the RTC counter.
* @param[out] p_restart_list_head List of repeating timers to be restarted.
*/
static void expired_timers_handler(uint32_t ticks_elapsed,
uint32_t ticks_previous,
app_timer_id_t * p_restart_list_head)
{
uint32_t ticks_expired = 0;
while (m_timer_id_head != TIMER_NULL)
{
timer_node_t * p_timer;
app_timer_id_t id_expired;
// Auto variable for current timer node.
p_timer = &mp_nodes[m_timer_id_head];
// Do nothing if timer did not expire
if (ticks_elapsed < p_timer->ticks_to_expire)
{
p_timer->ticks_to_expire -= ticks_elapsed;
break;
}
// Decrement ticks_elapsed and collect expired ticks.
ticks_elapsed -= p_timer->ticks_to_expire;
ticks_expired += p_timer->ticks_to_expire;
// Timer expired, set ticks_to_expire zero.
p_timer->ticks_to_expire = 0;
p_timer->is_running = false;
// Remove the expired timer from head.
id_expired = m_timer_id_head;
m_timer_id_head = p_timer->next;
// Timer will be restarted if periodic.
if (p_timer->ticks_periodic_interval != 0)
{
p_timer->ticks_at_start = (ticks_previous + ticks_expired) & MAX_RTC_COUNTER_VAL;
p_timer->ticks_first_interval = p_timer->ticks_periodic_interval;
p_timer->next = *p_restart_list_head;
*p_restart_list_head = id_expired;
}
}
}
/**@brief Function for handling timer list insertions.
*
* @param[in] p_restart_list_head List of repeating timers to be restarted.
*
* @return TRUE if Capture Compare register must be updated, FALSE otherwise.
*/
static bool list_insertions_handler(app_timer_id_t restart_list_head)
{
app_timer_id_t timer_id_old_head;
uint8_t user_id;
// Remember the old head, so as to decide if new compare needs to be set.
timer_id_old_head = m_timer_id_head;
user_id = m_user_array_size;
while (user_id--)
{
timer_user_t * p_user = &mp_users[user_id];
// Handle insertions of timers.
while ((restart_list_head != TIMER_NULL) || (p_user->first != p_user->last))
{
app_timer_id_t id_start;
timer_node_t * p_timer;
if (restart_list_head != TIMER_NULL)
{
id_start = restart_list_head;
p_timer = &mp_nodes[id_start];
restart_list_head = p_timer->next;
}
else
{
timer_user_op_t * p_user_op = &p_user->p_user_op_queue[p_user->first];
p_user->first++;
if (p_user->first == p_user->user_op_queue_size)
{
p_user->first = 0;
}
id_start = p_user_op->timer_id;
p_timer = &mp_nodes[id_start];
if ((p_user_op->op_type != TIMER_USER_OP_TYPE_START) || p_timer->is_running)
{
continue;
}
p_timer->ticks_at_start = p_user_op->params.start.ticks_at_start;
p_timer->ticks_first_interval = p_user_op->params.start.ticks_first_interval;
p_timer->ticks_periodic_interval = p_user_op->params.start.ticks_periodic_interval;
p_timer->p_context = p_user_op->params.start.p_context;
if (m_rtc1_reset)
{
p_timer->ticks_at_start = 0;
}
}
// Prepare the node to be inserted.
if (
((p_timer->ticks_at_start - m_ticks_latest) & MAX_RTC_COUNTER_VAL)
<
(MAX_RTC_COUNTER_VAL / 2)
)
{
p_timer->ticks_to_expire = ticks_diff_get(p_timer->ticks_at_start, m_ticks_latest) +
p_timer->ticks_first_interval;
}
else
{
uint32_t delta_current_start;
delta_current_start = ticks_diff_get(m_ticks_latest, p_timer->ticks_at_start);
if (p_timer->ticks_first_interval > delta_current_start)
{
p_timer->ticks_to_expire = p_timer->ticks_first_interval - delta_current_start;
}
else
{
p_timer->ticks_to_expire = 0;
}
}
p_timer->ticks_at_start = 0;
p_timer->ticks_first_interval = 0;
p_timer->is_running = true;
p_timer->next = TIMER_NULL;
// Insert into list
timer_list_insert(id_start);
}
}
return (m_timer_id_head != timer_id_old_head);
}
/**@brief Function for updating the Capture Compare register.
*/
static void compare_reg_update(app_timer_id_t timer_id_head_old)
{
// Setup the timeout for timers on the head of the list
if (m_timer_id_head != TIMER_NULL)
{
uint32_t ticks_to_expire = mp_nodes[m_timer_id_head].ticks_to_expire;
uint32_t pre_counter_val = rtc1_counter_get();
uint32_t cc = m_ticks_latest;
uint32_t ticks_elapsed = ticks_diff_get(pre_counter_val, cc) + RTC_COMPARE_OFFSET_MIN;
if (!m_rtc1_running)
{
// No timers were already running, start RTC
rtc1_start();
}
cc += (ticks_elapsed < ticks_to_expire) ? ticks_to_expire : ticks_elapsed;
cc &= MAX_RTC_COUNTER_VAL;
rtc1_compare0_set(cc);
uint32_t post_counter_val = rtc1_counter_get();
if (
(ticks_diff_get(post_counter_val, pre_counter_val) + RTC_COMPARE_OFFSET_MIN)
>
ticks_diff_get(cc, pre_counter_val)
)
{
// When this happens the COMPARE event may not be triggered by the RTC.
// The nRF51 Series User Specification states that if the COUNTER value is N
// (i.e post_counter_val = N), writing N or N+1 to a CC register may not trigger a
// COMPARE event. Hence the RTC interrupt is forcefully pended by calling the following
// function.
timer_timeouts_check_sched();
}
}
else
{
#if 1 /* leave the timer running so we can use the ticks for wall clock time */
// No timers are running, stop RTC
rtc1_stop();
#else
// Never match (or clear the interrupt)
rtc1_compare0_set(0);
#endif
}
}
/**@brief Function for handling changes to the timer list.
*/
static void timer_list_handler(void)
{
app_timer_id_t restart_list_head = TIMER_NULL;
uint32_t ticks_elapsed;
uint32_t ticks_previous;
bool ticks_have_elapsed;
bool compare_update;
app_timer_id_t timer_id_head_old;
// Back up the previous known tick and previous list head
ticks_previous = m_ticks_latest;
timer_id_head_old = m_timer_id_head;
// Get number of elapsed ticks
ticks_have_elapsed = elapsed_ticks_acquire(&ticks_elapsed);
// Handle list deletions
compare_update = list_deletions_handler();
// Handle expired timers
if (ticks_have_elapsed)
{
expired_timers_handler(ticks_elapsed, ticks_previous, &restart_list_head);
compare_update = true;
}
// Handle list insertions
if (list_insertions_handler(restart_list_head))
{
compare_update = true;
}
// Update compare register if necessary
if (compare_update)
{
compare_reg_update(timer_id_head_old);
}
m_rtc1_reset = false;
}
/**@brief Function for enqueueing a new operations queue entry.
*
* @param[in] p_user User that the entry is to be enqueued for.
* @param[in] last_index Index of the next last index to be enqueued.
*/
static void user_op_enque(timer_user_t * p_user, app_timer_id_t last_index)
{
p_user->last = last_index;
}
/**@brief Function for allocating a new operations queue entry.
*
* @param[in] p_user User that the entry is to be allocated for.
* @param[out] p_last_index Index of the next last index to be enqueued.
*
* @return Pointer to allocated queue entry, or NULL if queue is full.
*/
static timer_user_op_t * user_op_alloc(timer_user_t * p_user, app_timer_id_t * p_last_index)
{
app_timer_id_t last;
timer_user_op_t * p_user_op;
last = p_user->last + 1;
if (last == p_user->user_op_queue_size)
{
// Overflow case.
last = 0;
}
if (last == p_user->first)
{
// Queue is full.
return NULL;
}
*p_last_index = last;
p_user_op = &p_user->p_user_op_queue[p_user->last];
return p_user_op;
}
/**@brief Function for scheduling a Timer Start operation.
*
* @param[in] user_id Id of user calling this function.
* @param[in] timer_id Id of timer to start.
* @param[in] timeout_initial Time (in ticks) to first timer expiry.
* @param[in] timeout_periodic Time (in ticks) between periodic expiries.
* @param[in] p_context General purpose pointer. Will be passed to the timeout handler when
* the timer expires.
* @return NRF_SUCCESS on success, otherwise an error code.
*/
static uint32_t timer_start_op_schedule(timer_user_id_t user_id,
app_timer_id_t timer_id,
uint32_t timeout_initial,
uint32_t timeout_periodic,
void * p_context)
{
app_timer_id_t last_index;
timer_user_op_t * p_user_op = user_op_alloc(&mp_users[user_id], &last_index);
if (p_user_op == NULL)
{
return NRF_ERROR_NO_MEM;
}
p_user_op->op_type = TIMER_USER_OP_TYPE_START;
p_user_op->timer_id = timer_id;
p_user_op->params.start.ticks_at_start = rtc1_counter_get();
p_user_op->params.start.ticks_first_interval = timeout_initial;
p_user_op->params.start.ticks_periodic_interval = timeout_periodic;
p_user_op->params.start.p_context = p_context;
user_op_enque(&mp_users[user_id], last_index);
timer_list_handler_sched();
return NRF_SUCCESS;
}
/**@brief Function for scheduling a Timer Stop operation.
*
* @param[in] user_id Id of user calling this function.
* @param[in] timer_id Id of timer to stop.
*
* @return NRF_SUCCESS on successful scheduling a timer stop operation. NRF_ERROR_NO_MEM when there
* is no memory left to schedule the timer stop operation.
*/
static uint32_t timer_stop_op_schedule(timer_user_id_t user_id, app_timer_id_t timer_id)
{
app_timer_id_t last_index;
timer_user_op_t * p_user_op = user_op_alloc(&mp_users[user_id], &last_index);
if (p_user_op == NULL)
{
return NRF_ERROR_NO_MEM;
}
p_user_op->op_type = TIMER_USER_OP_TYPE_STOP;
p_user_op->timer_id = timer_id;
user_op_enque(&mp_users[user_id], last_index);
timer_list_handler_sched();
return NRF_SUCCESS;
}
/**@brief Function for scheduling a Timer Stop All operation.
*
* @param[in] user_id Id of user calling this function.
*/
static uint32_t timer_stop_all_op_schedule(timer_user_id_t user_id)
{
app_timer_id_t last_index;
timer_user_op_t * p_user_op = user_op_alloc(&mp_users[user_id], &last_index);
if (p_user_op == NULL)
{
return NRF_ERROR_NO_MEM;
}
p_user_op->op_type = TIMER_USER_OP_TYPE_STOP_ALL;
p_user_op->timer_id = TIMER_NULL;
user_op_enque(&mp_users[user_id], last_index);
timer_list_handler_sched();
return NRF_SUCCESS;
}
/**@brief Function for handling the RTC1 interrupt.
*
* @details Checks for timeouts, and executes timeout handlers for expired timers.
*/
void RTC1_IRQHandler(void)
{
// Clear all events
NRF_RTC1->EVENTS_COMPARE[0] = 0;
// Check for expired timers
timer_timeouts_check();
}
/**@brief Function for handling the SWI0 interrupt.
*
* @details Performs all updates to the timer list.
*/
void SWI0_IRQHandler(void)
{
timer_list_handler();
}
static void overflow_init(void)
{
APP_TIMER_OVERFLOW_COUNTER->POWER = 1;
APP_TIMER_OVERFLOW_COUNTER->TASKS_SHUTDOWN = 1;
APP_TIMER_OVERFLOW_COUNTER->TASKS_CLEAR = 1;
APP_TIMER_OVERFLOW_COUNTER->INTENCLR = -1; // disable all
APP_TIMER_OVERFLOW_COUNTER->MODE = TIMER_MODE_MODE_Counter;
APP_TIMER_OVERFLOW_COUNTER->BITMODE = TIMER_BITMODE_BITMODE_32Bit << TIMER_BITMODE_BITMODE_Pos;
APP_TIMER_OVERFLOW_COUNTER->PRESCALER = 0;
APP_TIMER_OVERFLOW_COUNTER->SHORTS = 0;
sd_ppi_channel_assign(APP_TIMER_PPI_CHANNEL_OVERFLOW,
&NRF_RTC1->EVENTS_OVRFLW,
&APP_TIMER_OVERFLOW_COUNTER->TASKS_COUNT);
sd_ppi_channel_enable_set(1 << APP_TIMER_PPI_CHANNEL_OVERFLOW);
APP_TIMER_OVERFLOW_COUNTER->TASKS_START = 1;
}
uint32_t app_timer_init(uint32_t prescaler,
uint8_t max_timers,
uint8_t op_queues_size,
void * p_buffer,
app_timer_evt_schedule_func_t evt_schedule_func)
{
int i;
// Check that buffer is correctly aligned
if (!is_word_aligned(p_buffer))
{
return NRF_ERROR_INVALID_PARAM;
}
// Check for NULL buffer
if (p_buffer == NULL)
{
return NRF_ERROR_INVALID_PARAM;
}
// Stop RTC to prevent any running timers from expiring (in case of reinitialization)
rtc1_stop();
m_evt_schedule_func = evt_schedule_func;
// Initialize timer node array
m_node_array_size = max_timers;
mp_nodes = p_buffer;
for (i = 0; i < max_timers; i++)
{
mp_nodes[i].state = STATE_FREE;
mp_nodes[i].is_running = false;
}
// Skip timer node array
p_buffer = &((uint8_t *)p_buffer)[max_timers * sizeof(timer_node_t)];
// Initialize users array
m_user_array_size = APP_TIMER_INT_LEVELS;
mp_users = p_buffer;
// Skip user array
p_buffer = &((uint8_t *)p_buffer)[APP_TIMER_INT_LEVELS * sizeof(timer_user_t)];
// Initialize operation queues
for (i = 0; i < APP_TIMER_INT_LEVELS; i++)
{
timer_user_t * p_user = &mp_users[i];
p_user->first = 0;
p_user->last = 0;
p_user->user_op_queue_size = op_queues_size;
p_user->p_user_op_queue = p_buffer;
// Skip operation queue
p_buffer = &((uint8_t *)p_buffer)[op_queues_size * sizeof(timer_user_op_t)];
}
m_timer_id_head = TIMER_NULL;
m_ticks_elapsed_q_read_ind = 0;
m_ticks_elapsed_q_write_ind = 0;
NVIC_ClearPendingIRQ(SWI0_IRQn);
NVIC_SetPriority(SWI0_IRQn, SWI0_IRQ_PRI);
NVIC_EnableIRQ(SWI0_IRQn);
rtc1_init(prescaler);
overflow_init();
m_ticks_latest = rtc1_counter_get();
return NRF_SUCCESS;
}
uint32_t app_timer_create(app_timer_id_t * p_timer_id,
app_timer_mode_t mode,
app_timer_timeout_handler_t timeout_handler)
{
int i;
// Check state and parameters
if (mp_nodes == NULL)
{
return NRF_ERROR_INVALID_STATE;
}
if (timeout_handler == NULL)
{
return NRF_ERROR_INVALID_PARAM;
}
if (p_timer_id == NULL)
{
return NRF_ERROR_INVALID_PARAM;
}
// Find free timer
for (i = 0; i < m_node_array_size; i++)
{
if (mp_nodes[i].state == STATE_FREE)
{
mp_nodes[i].state = STATE_ALLOCATED;
mp_nodes[i].mode = mode;
mp_nodes[i].p_timeout_handler = timeout_handler;
*p_timer_id = i;
return NRF_SUCCESS;
}
}
return NRF_ERROR_NO_MEM;
}
/**@brief Function for creating a timer user id from the current interrupt level.
*
* @return Timer user id.
*/
static timer_user_id_t user_id_get(void)
{
timer_user_id_t ret;
STATIC_ASSERT(APP_TIMER_INT_LEVELS == 3);
switch (current_int_priority_get())
{
case APP_IRQ_PRIORITY_HIGH:
ret = APP_HIGH_USER_ID;
break;
case APP_IRQ_PRIORITY_LOW:
ret = APP_LOW_USER_ID;
break;
default:
ret = THREAD_MODE_USER_ID;
break;
}
return ret;
}
uint32_t app_timer_start(app_timer_id_t timer_id, uint32_t timeout_ticks, void * p_context)
{
uint32_t timeout_periodic;
// Check state and parameters
if (mp_nodes == NULL)
{
return NRF_ERROR_INVALID_STATE;
}
if ((timer_id >= m_node_array_size) || (timeout_ticks < APP_TIMER_MIN_TIMEOUT_TICKS))
{
return NRF_ERROR_INVALID_PARAM;
}
if (mp_nodes[timer_id].state != STATE_ALLOCATED)
{
return NRF_ERROR_INVALID_STATE;
}
// Schedule timer start operation
timeout_periodic = (mp_nodes[timer_id].mode == APP_TIMER_MODE_REPEATED) ? timeout_ticks : 0;
return timer_start_op_schedule(user_id_get(),
timer_id,
timeout_ticks,
timeout_periodic,
p_context);
}
uint32_t app_timer_stop(app_timer_id_t timer_id)
{
// Check state and parameters
if (mp_nodes == NULL)
{
return NRF_ERROR_INVALID_STATE;
}
if (timer_id >= m_node_array_size)
{
return NRF_ERROR_INVALID_PARAM;
}
if (mp_nodes[timer_id].state != STATE_ALLOCATED)
{
return NRF_ERROR_INVALID_STATE;
}
// Schedule timer stop operation
return timer_stop_op_schedule(user_id_get(), timer_id);
}
uint32_t app_timer_stop_all(void)
{
// Check state
if (mp_nodes == NULL)
{
return NRF_ERROR_INVALID_STATE;
}
return timer_stop_all_op_schedule(user_id_get());
}
uint32_t app_timer_cnt_get(uint32_t * p_ticks)
{
*p_ticks = rtc1_counter_get();
return NRF_SUCCESS;
}
void app_timer_ticks(uint32_t *p_overflow, uint32_t *p_ticks)
{
uint32_t overflow0, overflow1, counter;
APP_TIMER_OVERFLOW_COUNTER->TASKS_CAPTURE[0] = 1; // trigger capture
overflow0 = APP_TIMER_OVERFLOW_COUNTER->CC[0]; // before
counter = NRF_RTC1->COUNTER;
APP_TIMER_OVERFLOW_COUNTER->TASKS_CAPTURE[1] = 1; // trigger capture
overflow1 = APP_TIMER_OVERFLOW_COUNTER->CC[1]; // after
if (overflow0 != overflow1)
{
/* overflow occurred (rare)
* we don't know if overflow1 changed before or after
* we sampled counter1, so we just sample again
*/
counter = NRF_RTC1->COUNTER;
}
*p_overflow = overflow1;
*p_ticks = counter;
}
uint32_t app_timer_cnt_diff_compute(uint32_t ticks_to,
uint32_t ticks_from,
uint32_t * p_ticks_diff)
{
*p_ticks_diff = ticks_diff_get(ticks_to, ticks_from);
return NRF_SUCCESS;
}
Raw
app_timer.h
/* Copyright (c) 2012 Nordic Semiconductor. All Rights Reserved.
*
* The information contained herein is property of Nordic Semiconductor ASA.
* Terms and conditions of usage are described in detail in NORDIC
* SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
*
* Licensees are granted free, non-transferable use of the information. NO
* WARRANTY of ANY KIND is provided. This heading must NOT be removed from
* the file.
*
*/
/** @file
*
* @defgroup app_timer Application Timer
* @{
* @ingroup app_common
*
* @brief Application timer functionality.
*
* @details It enables the application to create multiple timer instances based on the RTC1
* peripheral. Checking for timeouts and invokation of user timeout handlers is performed
* in the RTC1 interrupt handler. List handling is done using a software interrupt (SWI0).
* Both interrupt handlers are running in APP_LOW priority level.
*
* @note When calling app_timer_start() or app_timer_stop(), the timer operation is just queued,
* and the software interrupt is triggered. The actual timer start/stop operation is
* executed by the SWI0 interrupt handler. Since the SWI0 interrupt is running in APP_LOW,
* if the application code calling the timer function is running in APP_LOW or APP_HIGH,
* the timer operation will not be performed until the application handler has returned.
* This will be the case e.g. when stopping a timer from a timeout handler when not using
* the scheduler.
*
* @details Use the USE_SCHEDULER parameter of the APP_TIMER_INIT() macro to select if the
* @ref app_scheduler is to be used or not.
*
* @note Even if the scheduler is not used, app_timer.h will include app_scheduler.h, so when
* compiling, app_scheduler.h must be available in one of the compiler include paths.
*/
#ifndef APP_TIMER_H__
#define APP_TIMER_H__
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include "app_error.h"
#include "app_util.h"
#include "compiler_abstraction.h"
#define APP_TIMER_OVERFLOW_COUNTER NRF_TIMER1
#define APP_TIMER_PPI_CHANNEL_OVERFLOW 0
#define APP_TIMER_CLOCK_FREQ 32768 /**< Clock frequency of the RTC timer used to implement the app timer module. */
#define APP_TIMER_MIN_TIMEOUT_TICKS 5 /**< Minimum value of the timeout_ticks parameter of app_timer_start(). */
#define APP_TIMER_NODE_SIZE 32 /**< Size of app_timer.timer_node_t (only for use inside APP_TIMER_BUF_SIZE()). */
#define APP_TIMER_USER_OP_SIZE 24 /**< Size of app_timer.timer_user_op_t (only for use inside APP_TIMER_BUF_SIZE()). */
#define APP_TIMER_USER_SIZE 8 /**< Size of app_timer.timer_user_t (only for use inside APP_TIMER_BUF_SIZE()). */
#define APP_TIMER_INT_LEVELS 3 /**< Number of interrupt levels from where timer operations may be initiated (only for use inside APP_TIMER_BUF_SIZE()). */
/**@brief Compute number of bytes required to hold the application timer data structures.
*
* @param[in] MAX_TIMERS Maximum number of timers that can be created at any given time.
* @param[in] OP_QUEUE_SIZE Size of queues holding timer operations that are pending execution.
* NOTE: Due to the queue implementation, this size must be one more
* than the size that is actually needed.
*
* @return Required application timer buffer size (in bytes).
*/
#define APP_TIMER_BUF_SIZE(MAX_TIMERS, OP_QUEUE_SIZE) \
( \
((MAX_TIMERS) * APP_TIMER_NODE_SIZE) \
+ \
( \
APP_TIMER_INT_LEVELS \
* \
(APP_TIMER_USER_SIZE + ((OP_QUEUE_SIZE) + 1) * APP_TIMER_USER_OP_SIZE) \
) \
)
/**@brief Convert milliseconds to timer ticks.
*
* @note This macro uses 64 bit integer arithmetic, but as long as the macro parameters are
* constants (i.e. defines), the computation will be done by the preprocessor.
*
* @param[in] MS Milliseconds.
* @param[in] PRESCALER Value of the RTC1 PRESCALER register (must be the same value that was
* passed to APP_TIMER_INIT()).
*
* @note When using this macro, it is the responsibility of the developer to ensure that the
* values provided as input result in an output value that is supported by the
* @ref app_timer_start function. For example, when the ticks for 1 ms is needed, the
* maximum possible value of PRESCALER must be 6, when @ref APP_TIMER_CLOCK_FREQ is 32768.
* This will result in a ticks value as 5. Any higher value for PRESCALER will result in a
* ticks value that is not supported by this module.
*
* @return Number of timer ticks.
*/
#define APP_TIMER_TICKS(MS, PRESCALER)\
((uint32_t)ROUNDED_DIV((MS) * (uint64_t)APP_TIMER_CLOCK_FREQ, ((PRESCALER) + 1) * 1000))
/**@brief Timer id type. */
typedef uint32_t app_timer_id_t;
/**@brief Application timeout handler type. */
typedef void (*app_timer_timeout_handler_t)(void * p_context);
/**@brief Type of function for passing events from the timer module to the scheduler. */
typedef uint32_t (*app_timer_evt_schedule_func_t) (app_timer_timeout_handler_t timeout_handler,
void * p_context);
/**@brief Timer modes. */
typedef enum
{
APP_TIMER_MODE_SINGLE_SHOT, /**< The timer will expire only once. */
APP_TIMER_MODE_REPEATED /**< The timer will restart each time it expires. */
} app_timer_mode_t;
/**@brief Macro for initializing the application timer module.
*
* @details It will handle dimensioning and allocation of the memory buffer required by the timer,
* making sure that the buffer is correctly aligned. It will also connect the timer module
* to the scheduler (if specified).
*
* @note This module assumes that the LFCLK is already running. If it isn't, the module will
* be non-functional, since the RTC will not run. If you don't use a softdevice, you'll
* have to start the LFCLK manually. See the rtc_example's lfclk_config() function
* for an example of how to do this. If you use a softdevice, the LFCLK is started on
* softdevice init.
*
*
* @param[in] PRESCALER Value of the RTC1 PRESCALER register. This will decide the
* timer tick rate. Set to 0 for no prescaling.
* @param[in] MAX_TIMERS Maximum number of timers that can be created at any given time.
* @param[in] OP_QUEUES_SIZE Size of queues holding timer operations that are pending execution.
* @param[in] SCHEDULER_FUNC Pointer to scheduler event handler
*
* @note Since this macro allocates a buffer, it must only be called once (it is OK to call it
* several times as long as it is from the same location, e.g. to do a reinitialization).
*/
/*lint -emacro(506, APP_TIMER_INIT) */ /* Suppress "Constant value Boolean */
#define APP_TIMER_INIT(PRESCALER, MAX_TIMERS, OP_QUEUES_SIZE, SCHEDULER_FUNC) \
do \
{ \
static uint32_t APP_TIMER_BUF[CEIL_DIV(APP_TIMER_BUF_SIZE((MAX_TIMERS), \
(OP_QUEUES_SIZE) + 1), \
sizeof(uint32_t))]; \
uint32_t ERR_CODE = app_timer_init((PRESCALER), \
(MAX_TIMERS), \
(OP_QUEUES_SIZE) + 1, \
APP_TIMER_BUF, \
SCHEDULER_FUNC); \
APP_ERROR_CHECK(ERR_CODE); \
} while (0)
/**@brief Function for initializing the timer module.
*
* @note Normally initialization should be done using the APP_TIMER_INIT() macro, as that will both
* allocate the buffers needed by the timer module (including aligning the buffers correctly,
* and also take care of connecting the timer module to the scheduler (if specified).
*
* @param[in] prescaler Value of the RTC1 PRESCALER register. Set to 0 for no prescaling.
* @param[in] max_timers Maximum number of timers that can be created at any given time.
* @param[in] op_queues_size Size of queues holding timer operations that are pending
* execution. NOTE: Due to the queue implementation, this size must
* be one more than the size that is actually needed.
* @param[in] p_buffer Pointer to memory buffer for internal use in the app_timer
* module. The size of the buffer can be computed using the
* APP_TIMER_BUF_SIZE() macro. The buffer must be aligned to a
* 4 byte boundary.
* @param[in] evt_schedule_func Function for passing timeout events to the scheduler. Point to
* app_timer_evt_schedule() to connect to the scheduler. Set to NULL
* to make the timer module call the timeout handler directly from
* the timer interrupt handler.
*
* @retval NRF_SUCCESS Successful initialization.
* @retval NRF_ERROR_INVALID_PARAM Invalid parameter (buffer not aligned to a 4 byte
* boundary or NULL).
*/
uint32_t app_timer_init(uint32_t prescaler,
uint8_t max_timers,
uint8_t op_queues_size,
void * p_buffer,
app_timer_evt_schedule_func_t evt_schedule_func);
/**@brief Function for creating a timer instance.
*
* @param[out] p_timer_id Id of the newly created timer.
* @param[in] mode Timer mode.
* @param[in] timeout_handler Function to be executed when the timer expires.
*
* @retval NRF_SUCCESS Timer was successfully created.
* @retval NRF_ERROR_INVALID_PARAM Invalid parameter.
* @retval NRF_ERROR_INVALID_STATE Application timer module has not been initialized.
* @retval NRF_ERROR_NO_MEM Maximum number of timers has already been reached.
*
* @note This function does the timer allocation in the caller's context. It is also not protected
* by a critical region. Therefore care must be taken not to call it from several interrupt
* levels simultaneously.
*/
uint32_t app_timer_create(app_timer_id_t * p_timer_id,
app_timer_mode_t mode,
app_timer_timeout_handler_t timeout_handler);
/**@brief Function for starting a timer.
*
* @param[in] timer_id Id of timer to start.
* @param[in] timeout_ticks Number of ticks (of RTC1, including prescaling) to timeout event
* (minimum 5 ticks).
* @param[in] p_context General purpose pointer. Will be passed to the timeout handler when
* the timer expires.
*
* @retval NRF_SUCCESS Timer was successfully started.
* @retval NRF_ERROR_INVALID_PARAM Invalid parameter.
* @retval NRF_ERROR_INVALID_STATE Application timer module has not been initialized, or timer
* has not been created.
* @retval NRF_ERROR_NO_MEM Timer operations queue was full.
*
* @note The minimum timeout_ticks value is 5.
* @note For multiple active timers, timeouts occurring in close proximity to each other (in the
* range of 1 to 3 ticks) will have a positive jitter of maximum 3 ticks.
* @note When calling this method on a timer which is already running, the second start operation
* will be ignored.
*/
uint32_t app_timer_start(app_timer_id_t timer_id, uint32_t timeout_ticks, void * p_context);
/**@brief Function for stopping the specified timer.
*
* @param[in] timer_id Id of timer to stop.
*
* @retval NRF_SUCCESS Timer was successfully stopped.
* @retval NRF_ERROR_INVALID_PARAM Invalid parameter.
* @retval NRF_ERROR_INVALID_STATE Application timer module has not been initialized, or timer
* has not been created.
* @retval NRF_ERROR_NO_MEM Timer operations queue was full.
*/
uint32_t app_timer_stop(app_timer_id_t timer_id);
/**@brief Function for stopping all running timers.
*
* @retval NRF_SUCCESS All timers were successfully stopped.
* @retval NRF_ERROR_INVALID_STATE Application timer module has not been initialized.
* @retval NRF_ERROR_NO_MEM Timer operations queue was full.
*/
uint32_t app_timer_stop_all(void);
/**@brief Function for returning the current value of the RTC1 counter.
*
* @param[out] p_ticks Current value of the RTC1 counter.
*
* @retval NRF_SUCCESS Counter was successfully read.
*/
uint32_t app_timer_cnt_get(uint32_t * p_ticks);
/**@brief Return the number of times the timer has overflowed and the current counter value
*
* @param[out] p_overflow Number of times the RTC counter has overflowed
* @param[out] p_ticks Current value of RTC counter
*/
void app_timer_ticks(uint32_t *p_overflow, uint32_t *p_ticks);
/**@brief Function for computing the difference between two RTC1 counter values.
*
* @param[in] ticks_to Value returned by app_timer_cnt_get().
* @param[in] ticks_from Value returned by app_timer_cnt_get().
* @param[out] p_ticks_diff Number of ticks from ticks_from to ticks_to.
*
* @retval NRF_SUCCESS Counter difference was successfully computed.
*/
uint32_t app_timer_cnt_diff_compute(uint32_t ticks_to,
uint32_t ticks_from,
uint32_t * p_ticks_diff);
#endif // APP_TIMER_H__
/** @} */
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