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Superseded

This library was superseded by mbed-dev - https://os.mbed.com/users/mbed_official/code/mbed-dev/.

Development branch of the mbed library sources. This library is kept in synch with the latest changes from the mbed SDK and it is not guaranteed to work.

If you are looking for a stable and tested release, please import one of the official mbed library releases:

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common/ticker_api.c

Committer:
mbed_official
Date:
2015-04-28
Revision:
525:c320967f86b9

File content as of revision 525:c320967f86b9:

/* mbed Microcontroller Library
 * Copyright (c) 2015 ARM Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include <stddef.h>
#include "ticker_api.h"
#include "cmsis.h"

void ticker_set_handler(const ticker_data_t *const data, ticker_event_handler handler) {
    data->interface->init();

    data->queue->event_handler = handler;
}

void ticker_irq_handler(const ticker_data_t *const data) {
    data->interface->clear_interrupt();

    /* Go through all the pending TimerEvents */
    while (1) {
        if (data->queue->head == NULL) {
            // There are no more TimerEvents left, so disable matches.
            data->interface->disable_interrupt();
            return;
        }

        if ((int)(data->queue->head->timestamp - data->interface->read()) <= 0) {
            // This event was in the past:
            //      point to the following one and execute its handler
            ticker_event_t *p = data->queue->head;
            data->queue->head = data->queue->head->next;
            if (data->queue->event_handler != NULL) {
                (*data->queue->event_handler)(p->id); // NOTE: the handler can set new events
            }
            /* Note: We continue back to examining the head because calling the
             * event handler may have altered the chain of pending events. */
        } else {
            // This event and the following ones in the list are in the future:
            //      set it as next interrupt and return
            data->interface->set_interrupt(data->queue->head->timestamp);
            return;
        }
    }
}

void ticker_insert_event(const ticker_data_t *const data, ticker_event_t *obj, timestamp_t timestamp, uint32_t id) {
    /* disable interrupts for the duration of the function */
    __disable_irq();

    // initialise our data
    obj->timestamp = timestamp;
    obj->id = id;

    /* Go through the list until we either reach the end, or find
       an element this should come before (which is possibly the
       head). */
    ticker_event_t *prev = NULL, *p = data->queue->head;
    while (p != NULL) {
        /* check if we come before p */
        if ((int)(timestamp - p->timestamp) < 0) {
            break;
        }
        /* go to the next element */
        prev = p;
        p = p->next;
    }
    /* if prev is NULL we're at the head */
    if (prev == NULL) {
        data->queue->head = obj;
        data->interface->set_interrupt(timestamp);
    } else {
        prev->next = obj;
    }
    /* if we're at the end p will be NULL, which is correct */
    obj->next = p;

    __enable_irq();
}

void ticker_remove_event(const ticker_data_t *const data, ticker_event_t *obj) {
    __disable_irq();

    // remove this object from the list
    if (data->queue->head == obj) {
        // first in the list, so just drop me
        data->queue->head = obj->next;
        if (data->queue->head == NULL) {
            data->interface->disable_interrupt();
        } else {
            data->interface->set_interrupt(data->queue->head->timestamp);
        }
    } else {
        // find the object before me, then drop me
        ticker_event_t* p = data->queue->head;
        while (p != NULL) {
            if (p->next == obj) {
                p->next = obj->next;
                break;
            }
            p = p->next;
        }
    }

    __enable_irq();
}

timestamp_t ticker_read(const ticker_data_t *const data)
{
    return data->interface->read();
}

int ticker_get_next_timestamp(const ticker_data_t *const data, timestamp_t *timestamp)
{
    int ret = 0;

    /* if head is NULL, there are no pending events */
    __disable_irq();
    if (data->queue->head != NULL) {
        *timestamp = data->queue->head->timestamp;
        ret = 1;
    }
    __enable_irq();

    return ret;
}