ticker_api.h

00001 
00002 /** \addtogroup hal */
00003 /** @{*/
00004 /* mbed Microcontroller Library
00005  * Copyright (c) 2015 ARM Limited
00006  * SPDX-License-Identifier: Apache-2.0
00007  *
00008  * Licensed under the Apache License, Version 2.0 (the "License");
00009  * you may not use this file except in compliance with the License.
00010  * You may obtain a copy of the License at
00011  *
00012  *     http://www.apache.org/licenses/LICENSE-2.0
00013  *
00014  * Unless required by applicable law or agreed to in writing, software
00015  * distributed under the License is distributed on an "AS IS" BASIS,
00016  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00017  * See the License for the specific language governing permissions and
00018  * limitations under the License.
00019  */
00020 #ifndef MBED_TICKER_API_H
00021 #define MBED_TICKER_API_H
00022 
00023 #include <stdint.h>
00024 #include <stdbool.h>
00025 #include "device.h"
00026 
00027 /**
00028  * Legacy format representing a timestamp in us.
00029  * Given it is modeled as a 32 bit integer, this type can represent timestamp
00030  * up to 4294 seconds (71 minutes).
00031  * Prefer using us_timestamp_t which store timestamp as 64 bits integer.
00032  */
00033 typedef uint32_t timestamp_t;
00034 
00035 /**
00036  * A us timestamp stored in a 64 bit integer.
00037  * Can store timestamp up to 584810 years.
00038  */
00039 typedef uint64_t us_timestamp_t;
00040 
00041 /** Ticker's event structure
00042  */
00043 typedef struct ticker_event_s {
00044     us_timestamp_t         timestamp; /**< Event's timestamp */
00045     uint32_t               id;        /**< TimerEvent object */
00046     struct ticker_event_s *next;      /**< Next event in the queue */
00047 } ticker_event_t;
00048 
00049 typedef void (*ticker_event_handler)(uint32_t id);
00050 
00051 /** Information about the ticker implementation
00052  */
00053 typedef struct {
00054     uint32_t frequency;                           /**< Frequency in Hz this ticker runs at */
00055     uint32_t bits;                                /**< Number of bits this ticker supports */
00056 } ticker_info_t;
00057 
00058 
00059 /** Ticker's interface structure - required API for a ticker
00060  */
00061 typedef struct {
00062     void (*init)(void);                           /**< Init function */
00063     uint32_t (*read)(void);                       /**< Read function */
00064     void (*disable_interrupt)(void);              /**< Disable interrupt function */
00065     void (*clear_interrupt)(void);                /**< Clear interrupt function */
00066     void (*set_interrupt)(timestamp_t timestamp); /**< Set interrupt function */
00067     void (*fire_interrupt)(void);                 /**< Fire interrupt right-away */
00068     void (*free)(void);                           /**< Disable function */
00069     const ticker_info_t *(*get_info)(void);       /**< Return info about this ticker's implementation */
00070 } ticker_interface_t;
00071 
00072 /** Ticker's event queue structure
00073  */
00074 typedef struct {
00075     ticker_event_handler event_handler; /**< Event handler */
00076     ticker_event_t *head;               /**< A pointer to head */
00077     uint32_t frequency;                 /**< Frequency of the timer in Hz */
00078     uint32_t bitmask;                   /**< Mask to be applied to time values read */
00079     uint32_t max_delta;                 /**< Largest delta in ticks that can be used when scheduling */
00080     uint64_t max_delta_us;              /**< Largest delta in us that can be used when scheduling */
00081     uint32_t tick_last_read;            /**< Last tick read */
00082     uint64_t tick_remainder;            /**< Ticks that have not been added to base_time */
00083     us_timestamp_t present_time;        /**< Store the timestamp used for present time */
00084     bool initialized;                   /**< Indicate if the instance is initialized */
00085     bool dispatching;                   /**< The function ticker_irq_handler is dispatching */
00086     bool suspended;                     /**< Indicate if the instance is suspended */
00087     uint8_t frequency_shifts;           /**< If frequency is a value of 2^n, this is n, otherwise 0 */
00088 } ticker_event_queue_t;
00089 
00090 /** Ticker's data structure
00091  */
00092 typedef struct {
00093     const ticker_interface_t *interface; /**< Ticker's interface */
00094     ticker_event_queue_t *queue;         /**< Ticker's event queue */
00095 } ticker_data_t;
00096 
00097 #ifdef __cplusplus
00098 extern "C" {
00099 #endif
00100 
00101 /**
00102  * \defgroup hal_ticker Ticker HAL functions
00103  * @{
00104  */
00105 
00106 /** Initialize a ticker and set the event handler
00107  *
00108  * @param ticker The ticker object.
00109  * @param handler A handler to be set
00110  */
00111 void ticker_set_handler(const ticker_data_t *const ticker, ticker_event_handler handler);
00112 
00113 /** IRQ handler that goes through the events to trigger overdue events.
00114  *
00115  * @param ticker The ticker object.
00116  */
00117 void ticker_irq_handler(const ticker_data_t *const ticker);
00118 
00119 /** Remove an event from the queue
00120  *
00121  * @param ticker The ticker object.
00122  * @param obj  The event object to be removed from the queue
00123  */
00124 void ticker_remove_event(const ticker_data_t *const ticker, ticker_event_t *obj);
00125 
00126 /** Insert an event to the queue
00127  *
00128  * The event will be executed in timestamp - ticker_read().
00129  *
00130  * @warning This function does not consider timestamp in the past. If an event
00131  * is inserted with a timestamp less than the current timestamp then the event
00132  * will be executed in timestamp - ticker_read() us.
00133  * The internal counter wrap very quickly it is hard to decide weither an
00134  * event is in the past or in 1 hour.
00135  *
00136  * @note prefer the use of ticker_insert_event_us which allows registration of
00137  * absolute timestamp.
00138  *
00139  * @param ticker    The ticker object.
00140  * @param obj       The event object to be inserted to the queue
00141  * @param timestamp The event's timestamp
00142  * @param id        The event object
00143  */
00144 void ticker_insert_event(const ticker_data_t *const ticker, ticker_event_t *obj, timestamp_t timestamp, uint32_t id);
00145 
00146 /** Insert an event to the queue
00147  *
00148  * The event will be executed in timestamp - ticker_read_us() us.
00149  *
00150  * @note If an event is inserted with a timestamp less than the current
00151  * timestamp then the event will be scheduled immediately resulting in
00152  * an instant call to event handler.
00153  *
00154  * @param ticker    The ticker object.
00155  * @param obj       The event object to be inserted to the queue
00156  * @param timestamp The event's timestamp
00157  * @param id        The event object
00158  */
00159 void ticker_insert_event_us(const ticker_data_t *const ticker, ticker_event_t *obj, us_timestamp_t timestamp, uint32_t id);
00160 
00161 /** Read the current (relative) ticker's timestamp
00162  *
00163  * @warning Return a relative timestamp because the counter wrap every 4294
00164  * seconds.
00165  *
00166  * @param ticker The ticker object.
00167  * @return The current timestamp
00168  */
00169 timestamp_t ticker_read(const ticker_data_t *const ticker);
00170 
00171 /** Read the current (absolute) ticker's timestamp
00172  *
00173  * @warning Return an absolute timestamp counting from the initialization of the
00174  * ticker.
00175  *
00176  * @param ticker The ticker object.
00177  * @return The current timestamp
00178  */
00179 us_timestamp_t ticker_read_us(const ticker_data_t *const ticker);
00180 
00181 /** Read the next event's timestamp
00182  *
00183  * @param ticker        The ticker object.
00184  * @param timestamp     The timestamp object.
00185  * @return 1 if timestamp is pending event, 0 if there's no event pending
00186  */
00187 int ticker_get_next_timestamp(const ticker_data_t *const ticker, timestamp_t *timestamp);
00188 
00189 /** Suspend this ticker
00190  *
00191  * When suspended reads will always return the same time and no
00192  * events will be dispatched. When suspended the common layer
00193  * will only ever call the interface function clear_interrupt()
00194  * and that is only if ticker_irq_handler is called.
00195  *
00196  *
00197  * @param ticker        The ticker object.
00198  */
00199 void ticker_suspend(const ticker_data_t *const ticker);
00200 
00201 /** Resume this ticker
00202  *
00203  * When resumed the ticker will ignore any time that has passed
00204  * and continue counting up where it left off.
00205  *
00206  * @param ticker        The ticker object.
00207  */
00208 void ticker_resume(const ticker_data_t *const ticker);
00209 
00210 /* Private functions
00211  *
00212  * @cond PRIVATE
00213  *
00214  */
00215 
00216 int _ticker_match_interval_passed(timestamp_t prev_tick, timestamp_t cur_tick, timestamp_t match_tick);
00217 
00218 /*
00219  * @endcond PRIVATE
00220  *
00221  */
00222 
00223 /**@}*/
00224 
00225 #ifdef __cplusplus
00226 }
00227 #endif
00228 
00229 #endif
00230 
00231 /** @}*/