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  * Maximum delta (in us) between too interrupts.
00028  */
00029 #define MBED_TICKER_INTERRUPT_TIMESTAMP_MAX_DELTA   0x70000000ULL
00030 
00031 /**
00032  * Legacy format representing a timestamp in us.
00033  * Given it is modeled as a 32 bit integer, this type can represent timestamp
00034  * up to 4294 seconds (71 minutes).
00035  * Prefer using us_timestamp_t which store timestamp as 64 bits integer.
00036  */
00037 typedef uint32_t timestamp_t;
00038 
00039 /**
00040  * A us timestamp stored in a 64 bit integer.
00041  * Can store timestamp up to 584810 years.
00042  */
00043 typedef uint64_t us_timestamp_t;
00044 
00045 /** Ticker's event structure
00046  */
00047 typedef struct ticker_event_s {
00048     us_timestamp_t         timestamp; /**< Event's timestamp */
00049     uint32_t               id;        /**< TimerEvent object */
00050     struct ticker_event_s *next;      /**< Next event in the queue */
00051 } ticker_event_t;
00052 
00053 typedef void (*ticker_event_handler)(uint32_t id);
00054 
00055 /** Ticker's interface structure - required API for a ticker
00056  */
00057 typedef struct {
00058     void (*init)(void);                           /**< Init function */
00059     uint32_t (*read)(void);                       /**< Read function */
00060     void (*disable_interrupt)(void);              /**< Disable interrupt function */
00061     void (*clear_interrupt)(void);                /**< Clear interrupt function */
00062     void (*set_interrupt)(timestamp_t timestamp); /**< Set interrupt function */
00063 } ticker_interface_t;
00064 
00065 /** Ticker's event queue structure
00066  */
00067 typedef struct {
00068     ticker_event_handler event_handler; /**< Event handler */
00069     ticker_event_t *head;               /**< A pointer to head */
00070     us_timestamp_t present_time;        /**< Store the timestamp used for present time */
00071     bool initialized;                   /**< Indicate if the instance is initialized */
00072 } ticker_event_queue_t;
00073 
00074 /** Ticker's data structure
00075  */
00076 typedef struct {
00077     const ticker_interface_t *interface; /**< Ticker's interface */
00078     ticker_event_queue_t *queue;         /**< Ticker's event queue */
00079 } ticker_data_t;
00080 
00081 #ifdef __cplusplus
00082 extern "C" {
00083 #endif
00084 
00085 /**
00086  * \defgroup hal_ticker Ticker HAL functions
00087  * @{
00088  */
00089 
00090 /** Initialize a ticker and set the event handler
00091  *
00092  * @param ticker The ticker object.
00093  * @param handler A handler to be set
00094  */
00095 void ticker_set_handler(const ticker_data_t *const ticker, ticker_event_handler handler);
00096 
00097 /** IRQ handler that goes through the events to trigger overdue events.
00098  *
00099  * @param ticker The ticker object.
00100  */
00101 void ticker_irq_handler(const ticker_data_t *const ticker);
00102 
00103 /** Remove an event from the queue
00104  *
00105  * @param ticker The ticker object.
00106  * @param obj  The event object to be removed from the queue
00107  */
00108 void ticker_remove_event(const ticker_data_t *const ticker, ticker_event_t *obj);
00109 
00110 /** Insert an event to the queue
00111  *
00112  * The event will be executed in timestamp - ticker_read().
00113  *
00114  * @warning This function does not consider timestamp in the past. If an event
00115  * is inserted with a timestamp less than the current timestamp then the event
00116  * will be executed in timestamp - ticker_read() us.
00117  * The internal counter wrap very quickly it is hard to decide weither an
00118  * event is in the past or in 1 hour.
00119  *
00120  * @note prefer the use of ticker_insert_event_us which allows registration of
00121  * absolute timestamp.
00122  *
00123  * @param ticker    The ticker object.
00124  * @param obj       The event object to be inserted to the queue
00125  * @param timestamp The event's timestamp
00126  * @param id        The event object
00127  */
00128 void ticker_insert_event(const ticker_data_t *const ticker, ticker_event_t *obj, timestamp_t timestamp, uint32_t id);
00129 
00130 /** Insert an event to the queue
00131  *
00132  * The event will be executed in timestamp - ticker_read_us() us.
00133  *
00134  * @warning If an event is inserted with a timestamp less than the current
00135  * timestamp then the event will **not** be inserted.
00136  *
00137  * @param ticker    The ticker object.
00138  * @param obj       The event object to be inserted to the queue
00139  * @param timestamp The event's timestamp
00140  * @param id        The event object
00141  */
00142 void ticker_insert_event_us(const ticker_data_t *const ticker, ticker_event_t *obj, us_timestamp_t timestamp, uint32_t id);
00143 
00144 /** Read the current (relative) ticker's timestamp
00145  *
00146  * @warning Return a relative timestamp because the counter wrap every 4294
00147  * seconds.
00148  *
00149  * @param ticker The ticker object.
00150  * @return The current timestamp
00151  */
00152 timestamp_t ticker_read(const ticker_data_t *const ticker);
00153 
00154 /** Read the current (absolute) ticker's timestamp
00155  *
00156  * @warning Return an absolute timestamp counting from the initialization of the
00157  * ticker.
00158  *
00159  * @param ticker The ticker object.
00160  * @return The current timestamp
00161  */
00162 us_timestamp_t ticker_read_us(const ticker_data_t *const ticker);
00163 
00164 /** Read the next event's timestamp
00165  *
00166  * @param ticker The ticker object.
00167  * @return 1 if timestamp is pending event, 0 if there's no event pending
00168  */
00169 int ticker_get_next_timestamp(const ticker_data_t *const ticker, timestamp_t *timestamp);
00170 
00171 /**@}*/
00172 
00173 #ifdef __cplusplus
00174 }
00175 #endif
00176 
00177 #endif
00178 
00179 /** @}*/
00180