zain aftab / mbed-src

mbed library sources

Fork of mbed-src by mbed official

common/us_ticker_api.c@485:b5ae48b573d3, 2015-03-03 (annotated)

Committer:
mbed_official
Date:
Tue Mar 03 07:15:07 2015 +0000
Revision:
485:b5ae48b573d3
Parent:
482:ca51ab3eed5a
Child:
496:01cb89f68337
Synchronized with git revision 38514db08e270ed489f24230e15a248e23ca5a95



Full URL: https://github.com/mbedmicro/mbed/commit/38514db08e270ed489f24230e15a248e23ca5a95/



Fix issue #934: Handled condition when head is NULL.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 4:c4bfb462ca53 1 /* mbed Microcontroller Library
emilmont 4:c4bfb462ca53 2 * Copyright (c) 2006-2013 ARM Limited
emilmont 4:c4bfb462ca53 3 *
emilmont 4:c4bfb462ca53 4 * Licensed under the Apache License, Version 2.0 (the "License");
emilmont 4:c4bfb462ca53 5 * you may not use this file except in compliance with the License.
emilmont 4:c4bfb462ca53 6 * You may obtain a copy of the License at
emilmont 4:c4bfb462ca53 7 *
emilmont 4:c4bfb462ca53 8 * http://www.apache.org/licenses/LICENSE-2.0
emilmont 4:c4bfb462ca53 9 *
emilmont 4:c4bfb462ca53 10 * Unless required by applicable law or agreed to in writing, software
emilmont 4:c4bfb462ca53 11 * distributed under the License is distributed on an "AS IS" BASIS,
emilmont 4:c4bfb462ca53 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
emilmont 4:c4bfb462ca53 13 * See the License for the specific language governing permissions and
emilmont 4:c4bfb462ca53 14 * limitations under the License.
emilmont 4:c4bfb462ca53 15 */
emilmont 4:c4bfb462ca53 16 #include <stddef.h>
emilmont 4:c4bfb462ca53 17 #include "us_ticker_api.h"
emilmont 6:6dfdb79ccc45 18 #include "cmsis.h"
emilmont 4:c4bfb462ca53 19
emilmont 4:c4bfb462ca53 20 static ticker_event_handler event_handler;
emilmont 4:c4bfb462ca53 21 static ticker_event_t *head = NULL;
emilmont 4:c4bfb462ca53 22
emilmont 4:c4bfb462ca53 23 void us_ticker_set_handler(ticker_event_handler handler) {
emilmont 4:c4bfb462ca53 24 us_ticker_init();
mbed_official 221:8276e3a4886f 25
emilmont 4:c4bfb462ca53 26 event_handler = handler;
emilmont 4:c4bfb462ca53 27 }
emilmont 4:c4bfb462ca53 28
emilmont 4:c4bfb462ca53 29 void us_ticker_irq_handler(void) {
emilmont 4:c4bfb462ca53 30 us_ticker_clear_interrupt();
mbed_official 221:8276e3a4886f 31
emilmont 4:c4bfb462ca53 32 /* Go through all the pending TimerEvents */
emilmont 4:c4bfb462ca53 33 while (1) {
emilmont 4:c4bfb462ca53 34 if (head == NULL) {
emilmont 4:c4bfb462ca53 35 // There are no more TimerEvents left, so disable matches.
emilmont 4:c4bfb462ca53 36 us_ticker_disable_interrupt();
emilmont 4:c4bfb462ca53 37 return;
emilmont 4:c4bfb462ca53 38 }
mbed_official 221:8276e3a4886f 39
mbed_official 388:fc1c6dc472ca 40 if ((int)(head->timestamp - us_ticker_read()) <= 0) {
emilmont 4:c4bfb462ca53 41 // This event was in the past:
emilmont 4:c4bfb462ca53 42 // point to the following one and execute its handler
emilmont 4:c4bfb462ca53 43 ticker_event_t *p = head;
emilmont 4:c4bfb462ca53 44 head = head->next;
emilmont 4:c4bfb462ca53 45 if (event_handler != NULL) {
emilmont 4:c4bfb462ca53 46 event_handler(p->id); // NOTE: the handler can set new events
emilmont 4:c4bfb462ca53 47 }
mbed_official 304:89b9c3a9a045 48 /* Note: We continue back to examining the head because calling the
mbed_official 304:89b9c3a9a045 49 * event handler may have altered the chain of pending events. */
emilmont 4:c4bfb462ca53 50 } else {
emilmont 4:c4bfb462ca53 51 // This event and the following ones in the list are in the future:
emilmont 4:c4bfb462ca53 52 // set it as next interrupt and return
emilmont 4:c4bfb462ca53 53 us_ticker_set_interrupt(head->timestamp);
emilmont 4:c4bfb462ca53 54 return;
emilmont 4:c4bfb462ca53 55 }
emilmont 4:c4bfb462ca53 56 }
emilmont 4:c4bfb462ca53 57 }
emilmont 4:c4bfb462ca53 58
mbed_official 304:89b9c3a9a045 59 void us_ticker_insert_event(ticker_event_t *obj, timestamp_t timestamp, uint32_t id) {
emilmont 4:c4bfb462ca53 60 /* disable interrupts for the duration of the function */
emilmont 4:c4bfb462ca53 61 __disable_irq();
mbed_official 221:8276e3a4886f 62
emilmont 4:c4bfb462ca53 63 // initialise our data
emilmont 4:c4bfb462ca53 64 obj->timestamp = timestamp;
emilmont 4:c4bfb462ca53 65 obj->id = id;
mbed_official 221:8276e3a4886f 66
emilmont 4:c4bfb462ca53 67 /* Go through the list until we either reach the end, or find
emilmont 4:c4bfb462ca53 68 an element this should come before (which is possibly the
emilmont 4:c4bfb462ca53 69 head). */
emilmont 4:c4bfb462ca53 70 ticker_event_t *prev = NULL, *p = head;
emilmont 4:c4bfb462ca53 71 while (p != NULL) {
emilmont 4:c4bfb462ca53 72 /* check if we come before p */
mbed_official 454:a290c6acf95e 73 if ((int)(timestamp - p->timestamp) < 0) {
emilmont 4:c4bfb462ca53 74 break;
emilmont 4:c4bfb462ca53 75 }
emilmont 4:c4bfb462ca53 76 /* go to the next element */
emilmont 4:c4bfb462ca53 77 prev = p;
emilmont 4:c4bfb462ca53 78 p = p->next;
emilmont 4:c4bfb462ca53 79 }
emilmont 4:c4bfb462ca53 80 /* if prev is NULL we're at the head */
emilmont 4:c4bfb462ca53 81 if (prev == NULL) {
emilmont 4:c4bfb462ca53 82 head = obj;
emilmont 4:c4bfb462ca53 83 us_ticker_set_interrupt(timestamp);
emilmont 4:c4bfb462ca53 84 } else {
emilmont 4:c4bfb462ca53 85 prev->next = obj;
emilmont 4:c4bfb462ca53 86 }
emilmont 4:c4bfb462ca53 87 /* if we're at the end p will be NULL, which is correct */
emilmont 4:c4bfb462ca53 88 obj->next = p;
mbed_official 221:8276e3a4886f 89
emilmont 4:c4bfb462ca53 90 __enable_irq();
emilmont 4:c4bfb462ca53 91 }
emilmont 4:c4bfb462ca53 92
emilmont 4:c4bfb462ca53 93 void us_ticker_remove_event(ticker_event_t *obj) {
emilmont 4:c4bfb462ca53 94 __disable_irq();
mbed_official 221:8276e3a4886f 95
emilmont 4:c4bfb462ca53 96 // remove this object from the list
emilmont 4:c4bfb462ca53 97 if (head == obj) {
emilmont 4:c4bfb462ca53 98 // first in the list, so just drop me
emilmont 4:c4bfb462ca53 99 head = obj->next;
mbed_official 304:89b9c3a9a045 100 if (head == NULL) {
mbed_official 304:89b9c3a9a045 101 us_ticker_disable_interrupt();
mbed_official 304:89b9c3a9a045 102 } else {
emilmont 4:c4bfb462ca53 103 us_ticker_set_interrupt(head->timestamp);
emilmont 4:c4bfb462ca53 104 }
emilmont 4:c4bfb462ca53 105 } else {
emilmont 4:c4bfb462ca53 106 // find the object before me, then drop me
emilmont 4:c4bfb462ca53 107 ticker_event_t* p = head;
emilmont 4:c4bfb462ca53 108 while (p != NULL) {
emilmont 4:c4bfb462ca53 109 if (p->next == obj) {
emilmont 4:c4bfb462ca53 110 p->next = obj->next;
emilmont 4:c4bfb462ca53 111 break;
emilmont 4:c4bfb462ca53 112 }
emilmont 4:c4bfb462ca53 113 p = p->next;
emilmont 4:c4bfb462ca53 114 }
emilmont 4:c4bfb462ca53 115 }
mbed_official 221:8276e3a4886f 116
emilmont 4:c4bfb462ca53 117 __enable_irq();
emilmont 4:c4bfb462ca53 118 }
mbed_official 482:ca51ab3eed5a 119
mbed_official 485:b5ae48b573d3 120 int us_ticker_get_next_timestamp(timestamp_t *timestamp) {
mbed_official 485:b5ae48b573d3 121 int ret = 0;
mbed_official 485:b5ae48b573d3 122
mbed_official 485:b5ae48b573d3 123 /* if head is NULL, there are no pending events */
mbed_official 485:b5ae48b573d3 124 __disable_irq();
mbed_official 485:b5ae48b573d3 125 if (head != NULL) {
mbed_official 485:b5ae48b573d3 126 *timestamp = head->timestamp;
mbed_official 485:b5ae48b573d3 127 ret = 1;
mbed_official 485:b5ae48b573d3 128 }
mbed_official 485:b5ae48b573d3 129 __enable_irq();
mbed_official 485:b5ae48b573d3 130
mbed_official 485:b5ae48b573d3 131 return ret;
mbed_official 482:ca51ab3eed5a 132 }