ticker_api.h

00001 
00002 /** \addtogroup hal */
00003 /** @{*/
00004 /* mbed Microcontroller Library
00005  * Copyright (c) 2015 ARM Limited
00006  *
00007  * Licensed under the Apache License, Version 2.0 (the "License");
00008  * you may not use this file except in compliance with the License.
00009  * You may obtain a copy of the License at
00010  *
00011  *     http://www.apache.org/licenses/LICENSE-2.0
00012  *
00013  * Unless required by applicable law or agreed to in writing, software
00014  * distributed under the License is distributed on an "AS IS" BASIS,
00015  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00016  * See the License for the specific language governing permissions and
00017  * limitations under the License.
00018  */
00019 #ifndef MBED_TICKER_API_H
00020 #define MBED_TICKER_API_H
00021 
00022 #include <stdint.h>
00023 #include <stdbool.h>
00024 #include "device.h"
00025 
00026 /**
00027  * Legacy format representing a timestamp in us.
00028  * Given it is modeled as a 32 bit integer, this type can represent timestamp
00029  * up to 4294 seconds (71 minutes).
00030  * Prefer using us_timestamp_t which store timestamp as 64 bits integer.
00031  */
00032 typedef uint32_t timestamp_t;
00033 
00034 /**
00035  * A us timestamp stored in a 64 bit integer.
00036  * Can store timestamp up to 584810 years.
00037  */
00038 typedef uint64_t us_timestamp_t;
00039 
00040 /** Ticker's event structure
00041  */
00042 typedef struct ticker_event_s {
00043     us_timestamp_t         timestamp; /**< Event's timestamp */
00044     uint32_t               id;        /**< TimerEvent object */
00045     struct ticker_event_s *next;      /**< Next event in the queue */
00046 } ticker_event_t;
00047 
00048 typedef void (*ticker_event_handler)(uint32_t id);
00049 
00050 /** Information about the ticker implementation
00051  */
00052 typedef struct {
00053     uint32_t frequency;                           /**< Frequency in Hz this ticker runs at */
00054     uint32_t bits;                                /**< Number of bits this ticker supports */
00055 } ticker_info_t;
00056 
00057 
00058 /** Ticker's interface structure - required API for a ticker
00059  */
00060 typedef struct {
00061     void (*init)(void);                           /**< Init function */
00062     uint32_t (*read)(void);                       /**< Read function */
00063     void (*disable_interrupt)(void);              /**< Disable interrupt function */
00064     void (*clear_interrupt)(void);                /**< Clear interrupt function */
00065     void (*set_interrupt)(timestamp_t timestamp); /**< Set interrupt function */
00066     void (*fire_interrupt)(void);                 /**< Fire interrupt right-away */
00067     const ticker_info_t *(*get_info)(void);       /**< Return info about this ticker's implementation */
00068 } ticker_interface_t;
00069 
00070 /** Ticker's event queue structure
00071  */
00072 typedef struct {
00073     ticker_event_handler event_handler; /**< Event handler */
00074     ticker_event_t *head;               /**< A pointer to head */
00075     uint32_t frequency;                 /**< Frequency of the timer in Hz */
00076     uint32_t bitmask;                   /**< Mask to be applied to time values read */
00077     uint32_t max_delta;                 /**< Largest delta in ticks that can be used when scheduling */
00078     uint64_t max_delta_us;              /**< Largest delta in us that can be used when scheduling */
00079     uint32_t tick_last_read;            /**< Last tick read */
00080     uint64_t tick_remainder;            /**< Ticks that have not been added to base_time */
00081     us_timestamp_t present_time;        /**< Store the timestamp used for present time */
00082     bool initialized;                   /**< Indicate if the instance is initialized */
00083 } ticker_event_queue_t;
00084 
00085 /** Ticker's data structure
00086  */
00087 typedef struct {
00088     const ticker_interface_t *interface; /**< Ticker's interface */
00089     ticker_event_queue_t *queue;         /**< Ticker's event queue */
00090 } ticker_data_t;
00091 
00092 #ifdef __cplusplus
00093 extern "C" {
00094 #endif
00095 
00096 /**
00097  * \defgroup hal_ticker Ticker HAL functions
00098  * @{
00099  */
00100 
00101 /** Initialize a ticker and set the event handler
00102  *
00103  * @param ticker The ticker object.
00104  * @param handler A handler to be set
00105  */
00106 void ticker_set_handler(const ticker_data_t *const ticker, ticker_event_handler handler);
00107 
00108 /** IRQ handler that goes through the events to trigger overdue events.
00109  *
00110  * @param ticker The ticker object.
00111  */
00112 void ticker_irq_handler(const ticker_data_t *const ticker);
00113 
00114 /** Remove an event from the queue
00115  *
00116  * @param ticker The ticker object.
00117  * @param obj  The event object to be removed from the queue
00118  */
00119 void ticker_remove_event(const ticker_data_t *const ticker, ticker_event_t *obj);
00120 
00121 /** Insert an event to the queue
00122  *
00123  * The event will be executed in timestamp - ticker_read().
00124  *
00125  * @warning This function does not consider timestamp in the past. If an event
00126  * is inserted with a timestamp less than the current timestamp then the event
00127  * will be executed in timestamp - ticker_read() us.
00128  * The internal counter wrap very quickly it is hard to decide weither an
00129  * event is in the past or in 1 hour.
00130  *
00131  * @note prefer the use of ticker_insert_event_us which allows registration of
00132  * absolute timestamp.
00133  *
00134  * @param ticker    The ticker object.
00135  * @param obj       The event object to be inserted to the queue
00136  * @param timestamp The event's timestamp
00137  * @param id        The event object
00138  */
00139 void ticker_insert_event(const ticker_data_t *const ticker, ticker_event_t *obj, timestamp_t timestamp, uint32_t id);
00140 
00141 /** Insert an event to the queue
00142  *
00143  * The event will be executed in timestamp - ticker_read_us() us.
00144  *
00145  * @note If an event is inserted with a timestamp less than the current
00146  * timestamp then the event will be scheduled immediately resulting in
00147  * an instant call to event handler.
00148  *
00149  * @param ticker    The ticker object.
00150  * @param obj       The event object to be inserted to the queue
00151  * @param timestamp The event's timestamp
00152  * @param id        The event object
00153  */
00154 void ticker_insert_event_us(const ticker_data_t *const ticker, ticker_event_t *obj, us_timestamp_t timestamp, uint32_t id);
00155 
00156 /** Read the current (relative) ticker's timestamp
00157  *
00158  * @warning Return a relative timestamp because the counter wrap every 4294
00159  * seconds.
00160  *
00161  * @param ticker The ticker object.
00162  * @return The current timestamp
00163  */
00164 timestamp_t ticker_read(const ticker_data_t *const ticker);
00165 
00166 /** Read the current (absolute) ticker's timestamp
00167  *
00168  * @warning Return an absolute timestamp counting from the initialization of the
00169  * ticker.
00170  *
00171  * @param ticker The ticker object.
00172  * @return The current timestamp
00173  */
00174 us_timestamp_t ticker_read_us(const ticker_data_t *const ticker);
00175 
00176 /** Read the next event's timestamp
00177  *
00178  * @param ticker        The ticker object.
00179  * @param timestamp     The timestamp object.
00180  * @return 1 if timestamp is pending event, 0 if there's no event pending
00181  */
00182 int ticker_get_next_timestamp(const ticker_data_t *const ticker, timestamp_t *timestamp);
00183 
00184 /* Private functions
00185  *
00186  * @cond PRIVATE
00187  *
00188  */
00189 
00190 int _ticker_match_interval_passed(timestamp_t prev_tick, timestamp_t cur_tick, timestamp_t match_tick);
00191 
00192 /*
00193  * @endcond PRIVATE
00194  *
00195  */
00196 
00197 /**@}*/
00198 
00199 #ifdef __cplusplus
00200 }
00201 #endif
00202 
00203 #endif
00204 
00205 /** @}*/