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118 lines
3.5 KiB
C
118 lines
3.5 KiB
C
/* mbed Microcontroller Library
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* Copyright (c) 2006-2013 ARM Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stddef.h>
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#include "us_ticker_api.h"
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#include "cmsis.h"
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static ticker_event_handler event_handler;
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static ticker_event_t *head = NULL;
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void us_ticker_set_handler(ticker_event_handler handler) {
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us_ticker_init();
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event_handler = handler;
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}
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void us_ticker_irq_handler(void) {
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us_ticker_clear_interrupt();
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/* Go through all the pending TimerEvents */
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while (1) {
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if (head == NULL) {
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// There are no more TimerEvents left, so disable matches.
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us_ticker_disable_interrupt();
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return;
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}
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if ((int)(head->timestamp - us_ticker_read()) <= 0) {
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// This event was in the past:
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// point to the following one and execute its handler
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ticker_event_t *p = head;
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head = head->next;
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if (event_handler != NULL) {
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event_handler(p->id); // NOTE: the handler can set new events
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}
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/* Note: We continue back to examining the head because calling the
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* event handler may have altered the chain of pending events. */
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} else {
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// This event and the following ones in the list are in the future:
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// set it as next interrupt and return
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us_ticker_set_interrupt(head->timestamp);
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return;
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}
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}
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}
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void us_ticker_insert_event(ticker_event_t *obj, timestamp_t timestamp, uint32_t id) {
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/* disable interrupts for the duration of the function */
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__disable_irq();
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// initialise our data
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obj->timestamp = timestamp;
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obj->id = id;
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/* Go through the list until we either reach the end, or find
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an element this should come before (which is possibly the
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head). */
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ticker_event_t *prev = NULL, *p = head;
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while (p != NULL) {
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/* check if we come before p */
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if ((int)(timestamp - p->timestamp) <= 0) {
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break;
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}
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/* go to the next element */
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prev = p;
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p = p->next;
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}
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/* if prev is NULL we're at the head */
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if (prev == NULL) {
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head = obj;
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us_ticker_set_interrupt(timestamp);
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} else {
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prev->next = obj;
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}
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/* if we're at the end p will be NULL, which is correct */
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obj->next = p;
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__enable_irq();
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}
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void us_ticker_remove_event(ticker_event_t *obj) {
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__disable_irq();
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// remove this object from the list
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if (head == obj) {
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// first in the list, so just drop me
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head = obj->next;
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if (head == NULL) {
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us_ticker_disable_interrupt();
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} else {
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us_ticker_set_interrupt(head->timestamp);
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}
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} else {
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// find the object before me, then drop me
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ticker_event_t* p = head;
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while (p != NULL) {
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if (p->next == obj) {
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p->next = obj->next;
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break;
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}
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p = p->next;
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}
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}
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__enable_irq();
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}
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