Elijah Stanger-Jones / mbed-dev

Lightweight Mbed Library for STM F4 and F7

hal/mbed_ticker_api.c@2:0edeaf13dfb2, 2021-02-04 (annotated)

Committer:
elijahsj
Date:
Thu Feb 04 20:44:34 2021 +0000
Revision:
2:0edeaf13dfb2
Parent:
0:083111ae2a11 
modfiied for spine board;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
saloutos 0:083111ae2a11 1 /* mbed Microcontroller Library
saloutos 0:083111ae2a11 2 * Copyright (c) 2015 ARM Limited
saloutos 0:083111ae2a11 3 *
saloutos 0:083111ae2a11 4 * Licensed under the Apache License, Version 2.0 (the "License");
saloutos 0:083111ae2a11 5 * you may not use this file except in compliance with the License.
saloutos 0:083111ae2a11 6 * You may obtain a copy of the License at
saloutos 0:083111ae2a11 7 *
saloutos 0:083111ae2a11 8 * http://www.apache.org/licenses/LICENSE-2.0
saloutos 0:083111ae2a11 9 *
saloutos 0:083111ae2a11 10 * Unless required by applicable law or agreed to in writing, software
saloutos 0:083111ae2a11 11 * distributed under the License is distributed on an "AS IS" BASIS,
saloutos 0:083111ae2a11 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
saloutos 0:083111ae2a11 13 * See the License for the specific language governing permissions and
saloutos 0:083111ae2a11 14 * limitations under the License.
saloutos 0:083111ae2a11 15 */
saloutos 0:083111ae2a11 16 #include <stdio.h>
saloutos 0:083111ae2a11 17 #include <stddef.h>
saloutos 0:083111ae2a11 18 #include "hal/ticker_api.h"
saloutos 0:083111ae2a11 19 #include "platform/mbed_critical.h"
saloutos 0:083111ae2a11 20
saloutos 0:083111ae2a11 21 static void schedule_interrupt(const ticker_data_t *const ticker);
saloutos 0:083111ae2a11 22 static void update_present_time(const ticker_data_t *const ticker);
saloutos 0:083111ae2a11 23
saloutos 0:083111ae2a11 24 /*
saloutos 0:083111ae2a11 25 * Initialize a ticker instance.
saloutos 0:083111ae2a11 26 */
saloutos 0:083111ae2a11 27 static void initialize(const ticker_data_t *ticker)
saloutos 0:083111ae2a11 28 {
saloutos 0:083111ae2a11 29 // return if the queue has already been initialized, in that case the
saloutos 0:083111ae2a11 30 // interface used by the queue is already initialized.
saloutos 0:083111ae2a11 31 if (ticker->queue->initialized) {
saloutos 0:083111ae2a11 32 return;
saloutos 0:083111ae2a11 33 }
saloutos 0:083111ae2a11 34
saloutos 0:083111ae2a11 35 ticker->interface->init();
saloutos 0:083111ae2a11 36
saloutos 0:083111ae2a11 37 ticker->queue->event_handler = NULL;
saloutos 0:083111ae2a11 38 ticker->queue->head = NULL;
saloutos 0:083111ae2a11 39 ticker->queue->present_time = 0;
saloutos 0:083111ae2a11 40 ticker->queue->initialized = true;
saloutos 0:083111ae2a11 41
saloutos 0:083111ae2a11 42 update_present_time(ticker);
saloutos 0:083111ae2a11 43 schedule_interrupt(ticker);
saloutos 0:083111ae2a11 44 }
saloutos 0:083111ae2a11 45
saloutos 0:083111ae2a11 46 /**
saloutos 0:083111ae2a11 47 * Set the event handler function of a ticker instance.
saloutos 0:083111ae2a11 48 */
saloutos 0:083111ae2a11 49 static void set_handler(const ticker_data_t *const ticker, ticker_event_handler handler)
saloutos 0:083111ae2a11 50 {
saloutos 0:083111ae2a11 51 ticker->queue->event_handler = handler;
saloutos 0:083111ae2a11 52 }
saloutos 0:083111ae2a11 53
saloutos 0:083111ae2a11 54 /*
saloutos 0:083111ae2a11 55 * Convert a 32 bit timestamp into a 64 bit timestamp.
saloutos 0:083111ae2a11 56 *
saloutos 0:083111ae2a11 57 * A 64 bit timestamp is used as the point of time of reference while the
saloutos 0:083111ae2a11 58 * timestamp to convert is relative to this point of time.
saloutos 0:083111ae2a11 59 *
saloutos 0:083111ae2a11 60 * The lower 32 bits of the timestamp returned will be equal to the timestamp to
saloutos 0:083111ae2a11 61 * convert.
saloutos 0:083111ae2a11 62 *
saloutos 0:083111ae2a11 63 * If the timestamp to convert is less than the lower 32 bits of the time
saloutos 0:083111ae2a11 64 * reference then the timestamp to convert is seen as an overflowed value and
saloutos 0:083111ae2a11 65 * the upper 32 bit of the timestamp returned will be equal to the upper 32 bit
saloutos 0:083111ae2a11 66 * of the reference point + 1.
saloutos 0:083111ae2a11 67 * Otherwise, the upper 32 bit returned will be equal to the upper 32 bit of the
saloutos 0:083111ae2a11 68 * reference point.
saloutos 0:083111ae2a11 69 *
saloutos 0:083111ae2a11 70 * @param ref: The 64 bit timestamp of reference.
saloutos 0:083111ae2a11 71 * @param timestamp: The timestamp to convert.
saloutos 0:083111ae2a11 72 */
saloutos 0:083111ae2a11 73 static us_timestamp_t convert_timestamp(us_timestamp_t ref, timestamp_t timestamp)
saloutos 0:083111ae2a11 74 {
saloutos 0:083111ae2a11 75 bool overflow = timestamp < ((timestamp_t) ref) ? true : false;
saloutos 0:083111ae2a11 76
saloutos 0:083111ae2a11 77 us_timestamp_t result = (ref & ~((us_timestamp_t)UINT32_MAX)) | timestamp;
saloutos 0:083111ae2a11 78 if (overflow) {
saloutos 0:083111ae2a11 79 result += (1ULL<<32);
saloutos 0:083111ae2a11 80 }
saloutos 0:083111ae2a11 81
saloutos 0:083111ae2a11 82 return result;
saloutos 0:083111ae2a11 83 }
saloutos 0:083111ae2a11 84
saloutos 0:083111ae2a11 85 /**
saloutos 0:083111ae2a11 86 * Update the present timestamp value of a ticker.
saloutos 0:083111ae2a11 87 */
saloutos 0:083111ae2a11 88 static void update_present_time(const ticker_data_t *const ticker)
saloutos 0:083111ae2a11 89 {
saloutos 0:083111ae2a11 90 ticker->queue->present_time = convert_timestamp(
saloutos 0:083111ae2a11 91 ticker->queue->present_time,
saloutos 0:083111ae2a11 92 ticker->interface->read()
saloutos 0:083111ae2a11 93 );
saloutos 0:083111ae2a11 94 }
saloutos 0:083111ae2a11 95
saloutos 0:083111ae2a11 96 /**
saloutos 0:083111ae2a11 97 * Compute the time when the interrupt has to be triggered and schedule it.
saloutos 0:083111ae2a11 98 *
saloutos 0:083111ae2a11 99 * If there is no event in the queue or the next event to execute is in more
saloutos 0:083111ae2a11 100 * than MBED_TICKER_INTERRUPT_TIMESTAMP_MAX_DELTA us from now then the ticker
saloutos 0:083111ae2a11 101 * irq will be scheduled in MBED_TICKER_INTERRUPT_TIMESTAMP_MAX_DELTA us.
saloutos 0:083111ae2a11 102 * Otherwise the irq will be scheduled to happen when the running counter reach
saloutos 0:083111ae2a11 103 * the timestamp of the first event in the queue.
saloutos 0:083111ae2a11 104 *
saloutos 0:083111ae2a11 105 * @note If there is no event in the queue then the interrupt is scheduled to
saloutos 0:083111ae2a11 106 * in MBED_TICKER_INTERRUPT_TIMESTAMP_MAX_DELTA. This is necessary to keep track
saloutos 0:083111ae2a11 107 * of the timer overflow.
saloutos 0:083111ae2a11 108 */
saloutos 0:083111ae2a11 109 static void schedule_interrupt(const ticker_data_t *const ticker)
saloutos 0:083111ae2a11 110 {
saloutos 0:083111ae2a11 111 update_present_time(ticker);
saloutos 0:083111ae2a11 112 uint32_t relative_timeout = MBED_TICKER_INTERRUPT_TIMESTAMP_MAX_DELTA;
saloutos 0:083111ae2a11 113
saloutos 0:083111ae2a11 114 if (ticker->queue->head) {
saloutos 0:083111ae2a11 115 us_timestamp_t present = ticker->queue->present_time;
saloutos 0:083111ae2a11 116 us_timestamp_t next_event_timestamp = ticker->queue->head->timestamp;
saloutos 0:083111ae2a11 117
saloutos 0:083111ae2a11 118 // if the event at the head of the queue is in the past then schedule
saloutos 0:083111ae2a11 119 // it immediately.
saloutos 0:083111ae2a11 120 if (next_event_timestamp <= present) {
saloutos 0:083111ae2a11 121 ticker->interface->fire_interrupt();
saloutos 0:083111ae2a11 122 return;
saloutos 0:083111ae2a11 123 } else if ((next_event_timestamp - present) < MBED_TICKER_INTERRUPT_TIMESTAMP_MAX_DELTA) {
saloutos 0:083111ae2a11 124 relative_timeout = next_event_timestamp - present;
saloutos 0:083111ae2a11 125 }
saloutos 0:083111ae2a11 126 }
saloutos 0:083111ae2a11 127
saloutos 0:083111ae2a11 128 us_timestamp_t new_match_time = ticker->queue->present_time + relative_timeout;
saloutos 0:083111ae2a11 129 ticker->interface->set_interrupt(new_match_time);
saloutos 0:083111ae2a11 130 // there could be a delay, reread the time, check if it was set in the past
saloutos 0:083111ae2a11 131 // As result, if it is already in the past, we fire it immediately
saloutos 0:083111ae2a11 132 update_present_time(ticker);
saloutos 0:083111ae2a11 133 us_timestamp_t present = ticker->queue->present_time;
saloutos 0:083111ae2a11 134 if (present >= new_match_time) {
saloutos 0:083111ae2a11 135 ticker->interface->fire_interrupt();
saloutos 0:083111ae2a11 136 }
saloutos 0:083111ae2a11 137 }
saloutos 0:083111ae2a11 138
saloutos 0:083111ae2a11 139 void ticker_set_handler(const ticker_data_t *const ticker, ticker_event_handler handler)
saloutos 0:083111ae2a11 140 {
saloutos 0:083111ae2a11 141 initialize(ticker);
saloutos 0:083111ae2a11 142 set_handler(ticker, handler);
saloutos 0:083111ae2a11 143 }
saloutos 0:083111ae2a11 144
saloutos 0:083111ae2a11 145 void ticker_irq_handler(const ticker_data_t *const ticker)
saloutos 0:083111ae2a11 146 {
saloutos 0:083111ae2a11 147 ticker->interface->clear_interrupt();
saloutos 0:083111ae2a11 148
saloutos 0:083111ae2a11 149 /* Go through all the pending TimerEvents */
saloutos 0:083111ae2a11 150 while (1) {
saloutos 0:083111ae2a11 151 if (ticker->queue->head == NULL) {
saloutos 0:083111ae2a11 152 break;
saloutos 0:083111ae2a11 153 }
saloutos 0:083111ae2a11 154
saloutos 0:083111ae2a11 155 // update the current timestamp used by the queue
saloutos 0:083111ae2a11 156 update_present_time(ticker);
saloutos 0:083111ae2a11 157
saloutos 0:083111ae2a11 158 if (ticker->queue->head->timestamp <= ticker->queue->present_time) {
saloutos 0:083111ae2a11 159 // This event was in the past:
saloutos 0:083111ae2a11 160 // point to the following one and execute its handler
saloutos 0:083111ae2a11 161 ticker_event_t *p = ticker->queue->head;
saloutos 0:083111ae2a11 162 ticker->queue->head = ticker->queue->head->next;
saloutos 0:083111ae2a11 163 if (ticker->queue->event_handler != NULL) {
saloutos 0:083111ae2a11 164 (*ticker->queue->event_handler)(p->id); // NOTE: the handler can set new events
saloutos 0:083111ae2a11 165 }
saloutos 0:083111ae2a11 166 /* Note: We continue back to examining the head because calling the
saloutos 0:083111ae2a11 167 * event handler may have altered the chain of pending events. */
saloutos 0:083111ae2a11 168 } else {
saloutos 0:083111ae2a11 169 break;
saloutos 0:083111ae2a11 170 }
saloutos 0:083111ae2a11 171 }
saloutos 0:083111ae2a11 172
saloutos 0:083111ae2a11 173 schedule_interrupt(ticker);
saloutos 0:083111ae2a11 174 }
saloutos 0:083111ae2a11 175
saloutos 0:083111ae2a11 176 void ticker_insert_event(const ticker_data_t *const ticker, ticker_event_t *obj, timestamp_t timestamp, uint32_t id)
saloutos 0:083111ae2a11 177 {
saloutos 0:083111ae2a11 178 core_util_critical_section_enter();
saloutos 0:083111ae2a11 179
saloutos 0:083111ae2a11 180 // update the current timestamp
saloutos 0:083111ae2a11 181 update_present_time(ticker);
saloutos 0:083111ae2a11 182 us_timestamp_t absolute_timestamp = convert_timestamp(
saloutos 0:083111ae2a11 183 ticker->queue->present_time,
saloutos 0:083111ae2a11 184 timestamp
saloutos 0:083111ae2a11 185 );
saloutos 0:083111ae2a11 186 core_util_critical_section_exit();
saloutos 0:083111ae2a11 187
saloutos 0:083111ae2a11 188 // defer to ticker_insert_event_us
saloutos 0:083111ae2a11 189 ticker_insert_event_us(
saloutos 0:083111ae2a11 190 ticker,
saloutos 0:083111ae2a11 191 obj, absolute_timestamp, id
saloutos 0:083111ae2a11 192 );
saloutos 0:083111ae2a11 193 }
saloutos 0:083111ae2a11 194
saloutos 0:083111ae2a11 195 void ticker_insert_event_us(const ticker_data_t *const ticker, ticker_event_t *obj, us_timestamp_t timestamp, uint32_t id)
saloutos 0:083111ae2a11 196 {
saloutos 0:083111ae2a11 197 core_util_critical_section_enter();
saloutos 0:083111ae2a11 198
saloutos 0:083111ae2a11 199 // update the current timestamp
saloutos 0:083111ae2a11 200 update_present_time(ticker);
saloutos 0:083111ae2a11 201
saloutos 0:083111ae2a11 202 // initialise our data
saloutos 0:083111ae2a11 203 obj->timestamp = timestamp;
saloutos 0:083111ae2a11 204 obj->id = id;
saloutos 0:083111ae2a11 205
saloutos 0:083111ae2a11 206 /* Go through the list until we either reach the end, or find
saloutos 0:083111ae2a11 207 an element this should come before (which is possibly the
saloutos 0:083111ae2a11 208 head). */
saloutos 0:083111ae2a11 209 ticker_event_t *prev = NULL, *p = ticker->queue->head;
saloutos 0:083111ae2a11 210 while (p != NULL) {
saloutos 0:083111ae2a11 211 /* check if we come before p */
saloutos 0:083111ae2a11 212 if (timestamp < p->timestamp) {
saloutos 0:083111ae2a11 213 break;
saloutos 0:083111ae2a11 214 }
saloutos 0:083111ae2a11 215 /* go to the next element */
saloutos 0:083111ae2a11 216 prev = p;
saloutos 0:083111ae2a11 217 p = p->next;
saloutos 0:083111ae2a11 218 }
saloutos 0:083111ae2a11 219
saloutos 0:083111ae2a11 220 /* if we're at the end p will be NULL, which is correct */
saloutos 0:083111ae2a11 221 obj->next = p;
saloutos 0:083111ae2a11 222
saloutos 0:083111ae2a11 223 /* if prev is NULL we're at the head */
saloutos 0:083111ae2a11 224 if (prev == NULL) {
saloutos 0:083111ae2a11 225 ticker->queue->head = obj;
saloutos 0:083111ae2a11 226 } else {
saloutos 0:083111ae2a11 227 prev->next = obj;
saloutos 0:083111ae2a11 228 }
saloutos 0:083111ae2a11 229
saloutos 0:083111ae2a11 230 schedule_interrupt(ticker);
saloutos 0:083111ae2a11 231
saloutos 0:083111ae2a11 232 core_util_critical_section_exit();
saloutos 0:083111ae2a11 233 }
saloutos 0:083111ae2a11 234
saloutos 0:083111ae2a11 235 void ticker_remove_event(const ticker_data_t *const ticker, ticker_event_t *obj)
saloutos 0:083111ae2a11 236 {
saloutos 0:083111ae2a11 237 core_util_critical_section_enter();
saloutos 0:083111ae2a11 238
saloutos 0:083111ae2a11 239 // remove this object from the list
saloutos 0:083111ae2a11 240 if (ticker->queue->head == obj) {
saloutos 0:083111ae2a11 241 // first in the list, so just drop me
saloutos 0:083111ae2a11 242 ticker->queue->head = obj->next;
saloutos 0:083111ae2a11 243 schedule_interrupt(ticker);
saloutos 0:083111ae2a11 244 } else {
saloutos 0:083111ae2a11 245 // find the object before me, then drop me
saloutos 0:083111ae2a11 246 ticker_event_t* p = ticker->queue->head;
saloutos 0:083111ae2a11 247 while (p != NULL) {
saloutos 0:083111ae2a11 248 if (p->next == obj) {
saloutos 0:083111ae2a11 249 p->next = obj->next;
saloutos 0:083111ae2a11 250 break;
saloutos 0:083111ae2a11 251 }
saloutos 0:083111ae2a11 252 p = p->next;
saloutos 0:083111ae2a11 253 }
saloutos 0:083111ae2a11 254 }
saloutos 0:083111ae2a11 255
saloutos 0:083111ae2a11 256 core_util_critical_section_exit();
saloutos 0:083111ae2a11 257 }
saloutos 0:083111ae2a11 258
saloutos 0:083111ae2a11 259 timestamp_t ticker_read(const ticker_data_t *const ticker)
saloutos 0:083111ae2a11 260 {
saloutos 0:083111ae2a11 261 return ticker_read_us(ticker);
saloutos 0:083111ae2a11 262 }
saloutos 0:083111ae2a11 263
saloutos 0:083111ae2a11 264 us_timestamp_t ticker_read_us(const ticker_data_t *const ticker)
saloutos 0:083111ae2a11 265 {
saloutos 0:083111ae2a11 266 initialize(ticker);
saloutos 0:083111ae2a11 267 update_present_time(ticker);
saloutos 0:083111ae2a11 268 return ticker->queue->present_time;
saloutos 0:083111ae2a11 269 }
saloutos 0:083111ae2a11 270
saloutos 0:083111ae2a11 271 int ticker_get_next_timestamp(const ticker_data_t *const data, timestamp_t *timestamp)
saloutos 0:083111ae2a11 272 {
saloutos 0:083111ae2a11 273 int ret = 0;
saloutos 0:083111ae2a11 274
saloutos 0:083111ae2a11 275 /* if head is NULL, there are no pending events */
saloutos 0:083111ae2a11 276 core_util_critical_section_enter();
saloutos 0:083111ae2a11 277 if (data->queue->head != NULL) {
saloutos 0:083111ae2a11 278 *timestamp = data->queue->head->timestamp;
saloutos 0:083111ae2a11 279 ret = 1;
saloutos 0:083111ae2a11 280 }
saloutos 0:083111ae2a11 281 core_util_critical_section_exit();
saloutos 0:083111ae2a11 282
saloutos 0:083111ae2a11 283 return ret;
saloutos 0:083111ae2a11 284 }