Lee Kai Xuan / mbed-os

mbed-os

Fork of mbed-os by erkin yucel

hal/mbed_ticker_api.c@0:f269e3021894, 2016-10-23 (annotated)

Committer:
elessair
Date:
Sun Oct 23 15:10:02 2016 +0000
Revision:
0:f269e3021894
Initial commit

Who changed what in which revision?

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elessair 0:f269e3021894 1 /* mbed Microcontroller Library
elessair 0:f269e3021894 2 * Copyright (c) 2015 ARM Limited
elessair 0:f269e3021894 3 *
elessair 0:f269e3021894 4 * Licensed under the Apache License, Version 2.0 (the "License");
elessair 0:f269e3021894 5 * you may not use this file except in compliance with the License.
elessair 0:f269e3021894 6 * You may obtain a copy of the License at
elessair 0:f269e3021894 7 *
elessair 0:f269e3021894 8 * http://www.apache.org/licenses/LICENSE-2.0
elessair 0:f269e3021894 9 *
elessair 0:f269e3021894 10 * Unless required by applicable law or agreed to in writing, software
elessair 0:f269e3021894 11 * distributed under the License is distributed on an "AS IS" BASIS,
elessair 0:f269e3021894 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
elessair 0:f269e3021894 13 * See the License for the specific language governing permissions and
elessair 0:f269e3021894 14 * limitations under the License.
elessair 0:f269e3021894 15 */
elessair 0:f269e3021894 16 #include <stddef.h>
elessair 0:f269e3021894 17 #include "hal/ticker_api.h"
elessair 0:f269e3021894 18 #include "platform/critical.h"
elessair 0:f269e3021894 19
elessair 0:f269e3021894 20 void ticker_set_handler(const ticker_data_t *const data, ticker_event_handler handler) {
elessair 0:f269e3021894 21 data->interface->init();
elessair 0:f269e3021894 22
elessair 0:f269e3021894 23 data->queue->event_handler = handler;
elessair 0:f269e3021894 24 }
elessair 0:f269e3021894 25
elessair 0:f269e3021894 26 void ticker_irq_handler(const ticker_data_t *const data) {
elessair 0:f269e3021894 27 data->interface->clear_interrupt();
elessair 0:f269e3021894 28
elessair 0:f269e3021894 29 /* Go through all the pending TimerEvents */
elessair 0:f269e3021894 30 while (1) {
elessair 0:f269e3021894 31 if (data->queue->head == NULL) {
elessair 0:f269e3021894 32 // There are no more TimerEvents left, so disable matches.
elessair 0:f269e3021894 33 data->interface->disable_interrupt();
elessair 0:f269e3021894 34 return;
elessair 0:f269e3021894 35 }
elessair 0:f269e3021894 36
elessair 0:f269e3021894 37 if ((int)(data->queue->head->timestamp - data->interface->read()) <= 0) {
elessair 0:f269e3021894 38 // This event was in the past:
elessair 0:f269e3021894 39 // point to the following one and execute its handler
elessair 0:f269e3021894 40 ticker_event_t *p = data->queue->head;
elessair 0:f269e3021894 41 data->queue->head = data->queue->head->next;
elessair 0:f269e3021894 42 if (data->queue->event_handler != NULL) {
elessair 0:f269e3021894 43 (*data->queue->event_handler)(p->id); // NOTE: the handler can set new events
elessair 0:f269e3021894 44 }
elessair 0:f269e3021894 45 /* Note: We continue back to examining the head because calling the
elessair 0:f269e3021894 46 * event handler may have altered the chain of pending events. */
elessair 0:f269e3021894 47 } else {
elessair 0:f269e3021894 48 // This event and the following ones in the list are in the future:
elessair 0:f269e3021894 49 // set it as next interrupt and return
elessair 0:f269e3021894 50 data->interface->set_interrupt(data->queue->head->timestamp);
elessair 0:f269e3021894 51 return;
elessair 0:f269e3021894 52 }
elessair 0:f269e3021894 53 }
elessair 0:f269e3021894 54 }
elessair 0:f269e3021894 55
elessair 0:f269e3021894 56 void ticker_insert_event(const ticker_data_t *const data, ticker_event_t *obj, timestamp_t timestamp, uint32_t id) {
elessair 0:f269e3021894 57 /* disable interrupts for the duration of the function */
elessair 0:f269e3021894 58 core_util_critical_section_enter();
elessair 0:f269e3021894 59
elessair 0:f269e3021894 60 // initialise our data
elessair 0:f269e3021894 61 obj->timestamp = timestamp;
elessair 0:f269e3021894 62 obj->id = id;
elessair 0:f269e3021894 63
elessair 0:f269e3021894 64 /* Go through the list until we either reach the end, or find
elessair 0:f269e3021894 65 an element this should come before (which is possibly the
elessair 0:f269e3021894 66 head). */
elessair 0:f269e3021894 67 ticker_event_t *prev = NULL, *p = data->queue->head;
elessair 0:f269e3021894 68 while (p != NULL) {
elessair 0:f269e3021894 69 /* check if we come before p */
elessair 0:f269e3021894 70 if ((int)(timestamp - p->timestamp) < 0) {
elessair 0:f269e3021894 71 break;
elessair 0:f269e3021894 72 }
elessair 0:f269e3021894 73 /* go to the next element */
elessair 0:f269e3021894 74 prev = p;
elessair 0:f269e3021894 75 p = p->next;
elessair 0:f269e3021894 76 }
elessair 0:f269e3021894 77 /* if prev is NULL we're at the head */
elessair 0:f269e3021894 78 if (prev == NULL) {
elessair 0:f269e3021894 79 data->queue->head = obj;
elessair 0:f269e3021894 80 data->interface->set_interrupt(timestamp);
elessair 0:f269e3021894 81 } else {
elessair 0:f269e3021894 82 prev->next = obj;
elessair 0:f269e3021894 83 }
elessair 0:f269e3021894 84 /* if we're at the end p will be NULL, which is correct */
elessair 0:f269e3021894 85 obj->next = p;
elessair 0:f269e3021894 86
elessair 0:f269e3021894 87 core_util_critical_section_exit();
elessair 0:f269e3021894 88 }
elessair 0:f269e3021894 89
elessair 0:f269e3021894 90 void ticker_remove_event(const ticker_data_t *const data, ticker_event_t *obj) {
elessair 0:f269e3021894 91 core_util_critical_section_enter();
elessair 0:f269e3021894 92
elessair 0:f269e3021894 93 // remove this object from the list
elessair 0:f269e3021894 94 if (data->queue->head == obj) {
elessair 0:f269e3021894 95 // first in the list, so just drop me
elessair 0:f269e3021894 96 data->queue->head = obj->next;
elessair 0:f269e3021894 97 if (data->queue->head == NULL) {
elessair 0:f269e3021894 98 data->interface->disable_interrupt();
elessair 0:f269e3021894 99 } else {
elessair 0:f269e3021894 100 data->interface->set_interrupt(data->queue->head->timestamp);
elessair 0:f269e3021894 101 }
elessair 0:f269e3021894 102 } else {
elessair 0:f269e3021894 103 // find the object before me, then drop me
elessair 0:f269e3021894 104 ticker_event_t* p = data->queue->head;
elessair 0:f269e3021894 105 while (p != NULL) {
elessair 0:f269e3021894 106 if (p->next == obj) {
elessair 0:f269e3021894 107 p->next = obj->next;
elessair 0:f269e3021894 108 break;
elessair 0:f269e3021894 109 }
elessair 0:f269e3021894 110 p = p->next;
elessair 0:f269e3021894 111 }
elessair 0:f269e3021894 112 }
elessair 0:f269e3021894 113
elessair 0:f269e3021894 114 core_util_critical_section_exit();
elessair 0:f269e3021894 115 }
elessair 0:f269e3021894 116
elessair 0:f269e3021894 117 timestamp_t ticker_read(const ticker_data_t *const data)
elessair 0:f269e3021894 118 {
elessair 0:f269e3021894 119 return data->interface->read();
elessair 0:f269e3021894 120 }
elessair 0:f269e3021894 121
elessair 0:f269e3021894 122 int ticker_get_next_timestamp(const ticker_data_t *const data, timestamp_t *timestamp)
elessair 0:f269e3021894 123 {
elessair 0:f269e3021894 124 int ret = 0;
elessair 0:f269e3021894 125
elessair 0:f269e3021894 126 /* if head is NULL, there are no pending events */
elessair 0:f269e3021894 127 core_util_critical_section_enter();
elessair 0:f269e3021894 128 if (data->queue->head != NULL) {
elessair 0:f269e3021894 129 *timestamp = data->queue->head->timestamp;
elessair 0:f269e3021894 130 ret = 1;
elessair 0:f269e3021894 131 }
elessair 0:f269e3021894 132 core_util_critical_section_exit();
elessair 0:f269e3021894 133
elessair 0:f269e3021894 134 return ret;
elessair 0:f269e3021894 135 }