base/libs/qdecoder/qQueue.c

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/*
 * Copyright 2008 The qDecoder Project. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE QDECODER PROJECT ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE QDECODER PROJECT BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef DISABLE_DATASTRUCTURE

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include "qDecoder.h"
#include "qInternal.h"

size_t qQueueSize(int max, size_t objsize) {
    size_t memsize = objsize * max;
    return memsize;
}

int qQueueInit(Q_QUEUE *queue, void* datamem, size_t datamemsize, size_t objsize) {
    if(queue == NULL || datamem == NULL || datamemsize <= 0 || objsize <= 0) return 0;

    // calculate max
    int max = datamemsize / objsize;
    if(max < 1) return false;

    // init structure
    queue->max = max;
    queue->objsize = objsize;
    queue->objarr = datamem;
    qQueueClear(queue);

    return max;
}

bool qQueueClear(Q_QUEUE *queue) {
    queue->used = 0;
    queue->head = 0;
    queue->tail = 0;

    return true;
}

bool qQueuePush(Q_QUEUE *queue, const void *object) {
    if(queue == NULL || object == NULL) return false;

    // check full
    if(queue->used == queue->max) {
        DEBUG("Queue full.");
        return false;
    }

    // append object
    void *dp = queue->objarr + (queue->objsize * queue->tail);
    memcpy(dp, object, queue->objsize);

    // adjust pointer
    queue->used++;
    queue->tail = (queue->tail + 1) % queue->max;

    return true;
}

bool qQueuePopFirst(Q_QUEUE *queue, void *object) {
    if(queue == NULL || object == NULL) return false;

    // check empty
    if(queue->used == 0) {
        DEBUG("Queue empty.");
        return false;
    }

    // pop object
    void *dp = queue->objarr + (queue->objsize * queue->head);
    memcpy(object, dp, queue->objsize);

    // adjust pointer
    queue->used--;
    queue->head = (queue->head + 1) % queue->max;

    return true;
}

bool qQueuePopLast(Q_QUEUE *queue, void *object) {
    if(queue == NULL || object == NULL) return false;

    // check empty
    if(queue->used == 0) {
        DEBUG("Queue empty.");
        return false;
    }

    // adjust pointer
    queue->tail = (queue->tail > 0) ? (queue->tail - 1) : (queue->max - 1);
    queue->used--;

    // pop object
    void *dp = queue->objarr + (queue->objsize * queue->tail);
    memcpy(object, dp, queue->objsize);

    return true;
}

bool qQueueStatus(Q_QUEUE *queue, int *used, int *max) {
    if(queue == NULL) return false;

    if(used != NULL) *used = queue->used;
    if(max != NULL) *max = queue->max;

    return true;
}

#endif /* DISABLE_DATASTRUCTURE */

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