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     void (*free)(void);                           /**< Disable function */
00068     const ticker_info_t *(*get_info)(void);       /**< Return info about this ticker's implementation */
00069 } ticker_interface_t;
00070 
00071 /** Ticker's event queue structure
00072  */
00073 typedef struct {
00074     ticker_event_handler event_handler; /**< Event handler */
00075     ticker_event_t *head;               /**< A pointer to head */
00076     uint32_t frequency;                 /**< Frequency of the timer in Hz */
00077     uint32_t bitmask;                   /**< Mask to be applied to time values read */
00078     uint32_t max_delta;                 /**< Largest delta in ticks that can be used when scheduling */
00079     uint64_t max_delta_us;              /**< Largest delta in us that can be used when scheduling */
00080     uint32_t tick_last_read;            /**< Last tick read */
00081     uint64_t tick_remainder;            /**< Ticks that have not been added to base_time */
00082     us_timestamp_t present_time;        /**< Store the timestamp used for present time */
00083     bool initialized;                   /**< Indicate if the instance is initialized */
00084     bool dispatching;                   /**< The function ticker_irq_handler is dispatching */
00085     bool suspended;                     /**< Indicate if the instance is suspended */
00086     uint8_t frequency_shifts;           /**< If frequency is a value of 2^n, this is n, otherwise 0 */
00087 } ticker_event_queue_t;
00088 
00089 /** Ticker's data structure
00090  */
00091 typedef struct {
00092     const ticker_interface_t *interface; /**< Ticker's interface */
00093     ticker_event_queue_t *queue;         /**< Ticker's event queue */
00094 } ticker_data_t;
00095 
00096 #ifdef __cplusplus
00097 extern "C" {
00098 #endif
00099 
00100 /**
00101  * \defgroup hal_ticker Ticker HAL functions
00102  * @{
00103  */
00104 
00105 /** Initialize a ticker and set the event handler
00106  *
00107  * @param ticker The ticker object.
00108  * @param handler A handler to be set
00109  */
00110 void ticker_set_handler(const ticker_data_t *const ticker, ticker_event_handler handler);
00111 
00112 /** IRQ handler that goes through the events to trigger overdue events.
00113  *
00114  * @param ticker The ticker object.
00115  */
00116 void ticker_irq_handler(const ticker_data_t *const ticker);
00117 
00118 /** Remove an event from the queue
00119  *
00120  * @param ticker The ticker object.
00121  * @param obj  The event object to be removed from the queue
00122  */
00123 void ticker_remove_event(const ticker_data_t *const ticker, ticker_event_t *obj);
00124 
00125 /** Insert an event to the queue
00126  *
00127  * The event will be executed in timestamp - ticker_read().
00128  *
00129  * @warning This function does not consider timestamp in the past. If an event
00130  * is inserted with a timestamp less than the current timestamp then the event
00131  * will be executed in timestamp - ticker_read() us.
00132  * The internal counter wrap very quickly it is hard to decide weither an
00133  * event is in the past or in 1 hour.
00134  *
00135  * @note prefer the use of ticker_insert_event_us which allows registration of
00136  * absolute timestamp.
00137  *
00138  * @param ticker    The ticker object.
00139  * @param obj       The event object to be inserted to the queue
00140  * @param timestamp The event's timestamp
00141  * @param id        The event object
00142  */
00143 void ticker_insert_event(const ticker_data_t *const ticker, ticker_event_t *obj, timestamp_t timestamp, uint32_t id);
00144 
00145 /** Insert an event to the queue
00146  *
00147  * The event will be executed in timestamp - ticker_read_us() us.
00148  *
00149  * @note If an event is inserted with a timestamp less than the current
00150  * timestamp then the event will be scheduled immediately resulting in
00151  * an instant call to event handler.
00152  *
00153  * @param ticker    The ticker object.
00154  * @param obj       The event object to be inserted to the queue
00155  * @param timestamp The event's timestamp
00156  * @param id        The event object
00157  */
00158 void ticker_insert_event_us(const ticker_data_t *const ticker, ticker_event_t *obj, us_timestamp_t timestamp, uint32_t id);
00159 
00160 /** Read the current (relative) ticker's timestamp
00161  *
00162  * @warning Return a relative timestamp because the counter wrap every 4294
00163  * seconds.
00164  *
00165  * @param ticker The ticker object.
00166  * @return The current timestamp
00167  */
00168 timestamp_t ticker_read(const ticker_data_t *const ticker);
00169 
00170 /** Read the current (absolute) ticker's timestamp
00171  *
00172  * @warning Return an absolute timestamp counting from the initialization of the
00173  * ticker.
00174  *
00175  * @param ticker The ticker object.
00176  * @return The current timestamp
00177  */
00178 us_timestamp_t ticker_read_us(const ticker_data_t *const ticker);
00179 
00180 /** Read the next event's timestamp
00181  *
00182  * @param ticker        The ticker object.
00183  * @param timestamp     The timestamp object.
00184  * @return 1 if timestamp is pending event, 0 if there's no event pending
00185  */
00186 int ticker_get_next_timestamp(const ticker_data_t *const ticker, timestamp_t *timestamp);
00187 
00188 /** Suspend this ticker
00189  *
00190  * When suspended reads will always return the same time and no
00191  * events will be dispatched. When suspended the common layer
00192  * will only ever call the interface function clear_interrupt()
00193  * and that is only if ticker_irq_handler is called.
00194  *
00195  *
00196  * @param ticker        The ticker object.
00197  */
00198 void ticker_suspend(const ticker_data_t *const ticker);
00199 
00200 /** Resume this ticker
00201  *
00202  * When resumed the ticker will ignore any time that has passed
00203  * and continue counting up where it left off.
00204  *
00205  * @param ticker        The ticker object.
00206  */
00207 void ticker_resume(const ticker_data_t *const ticker);
00208 
00209 /* Private functions
00210  *
00211  * @cond PRIVATE
00212  *
00213  */
00214 
00215 int _ticker_match_interval_passed(timestamp_t prev_tick, timestamp_t cur_tick, timestamp_t match_tick);
00216 
00217 /*
00218  * @endcond PRIVATE
00219  *
00220  */
00221 
00222 /**@}*/
00223 
00224 #ifdef __cplusplus
00225 }
00226 #endif
00227 
00228 #endif
00229 
00230 /** @}*/