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/*

 * Copyright (c) 2010, Mentor Graphics Corporation

 * 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.

 * 3. Neither the name of the <ORGANIZATION> nor the names of its contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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.

 */

#include <openmcapi.h>

typedef struct MCAPI_QNode_Struct

{

    struct MCAPI_QNode_Struct      *flink;

    struct MCAPI_QNode_Struct      *blink;

} MCAPI_QNODE;

/*************************************************************************

*

*   FUNCTION

*

*       mcapi_enqueue

*

*   DESCRIPTION

*

*       Enqueues an entry onto a given queue.

*

*   INPUTS

*

*       *queue_ptr              Pointer to the queue to which the entry

*                               is being enqueued.

*       *entry                  Pointer to the new queue entry.

*

*   OUTPUTS

*

*       None.

*

*************************************************************************/

void mcapi_enqueue(void *queue_ptr, void *entry)

{

    MCAPI_QNODE     *hdr = queue_ptr;

    MCAPI_QNODE     *item = entry;

    /* Set item's flink to point at NULL */

    item->flink = MCAPI_NULL;

    /* If there is currently a node in the linked list, we want add

     * item after that node

     */

    if (hdr->flink)

    {

        /* Make the last node's flink point to item */

        hdr->blink->flink = item;

        /* Make item's blink point to the old last node */

        item->blink = hdr->blink;

        /* Make hdr's blink point to the new last node, item */

        hdr->blink = item;

    }

    /* If the linked list was empty, we want both the hdr's flink and

     * the hdr's blink to point to item.  Both of item's links will

     * point to NULL, as there are no other nodes in the list

     */

    else

    {

        hdr->flink = hdr->blink = item;

        item->blink = MCAPI_NULL;

    }

}

/*************************************************************************

*

*   FUNCTION

*

*       mcapi_remove

*

*   DESCRIPTION

*

*       Removes an entry from a given queue.

*

*   INPUTS

*

*       *queue_ptr              Pointer to the queue from which the entry

*                               is being removed.

*       *entry                  Pointer to the queue entry to remove.

*

*   OUTPUTS

*

*       A pointer to the item that was removed.

*

*************************************************************************/

void *mcapi_remove(void *queue_ptr, void *entry)

{

    MCAPI_QNODE     *hdr = queue_ptr;

    MCAPI_QNODE     *item = entry;

    MCAPI_QNODE     *ent;

    /*  Search the linked list until item is found or the end of the list

     *  is reached.

     */

    for (ent = hdr->flink;( (ent) && (ent != item) ); ent = ent->flink)

        ;

    /*  If the item was found. */

    if (ent)

    {

        /* If we are deleting the list head, this is just a dequeue operation */

        if (hdr->flink == item)

            mcapi_dequeue(hdr);

        /*  If we are deleting the list tail, we need to reset the tail pointer

         *  and make the new tail point forward to 0.

         */

        else if (hdr->blink == item)

        {

            hdr->blink = item->blink;

            hdr->blink->flink = MCAPI_NULL;

        }

        /* We are removing this entry from the middle of the list */

        else

        {

            item->blink->flink = item->flink;

            item->flink->blink = item->blink;

        }

    }

    return (ent);

}

/*************************************************************************

*

*   FUNCTION

*

*       mcapi_dequeue

*

*   DESCRIPTION

*

*       Removes and returns the first entry in a queue.

*

*   INPUTS

*

*       *queue_ptr              Pointer to the queue from which the entry

*                               is being removed.

*

*   OUTPUTS

*

*       Pointer to the entry removed from the queue.

*

*************************************************************************/

void *mcapi_dequeue(void *queue_ptr)

{

   MCAPI_QNODE *hdr = queue_ptr;

   MCAPI_QNODE *ent;

   /* Create a pointer to the first node in the linked list */

   ent = hdr->flink;

   /* If there is a node in the list we want to remove it. */

   if (ent)

   {

       /* Make the hdr point the second node in the list */

       hdr->flink = ent->flink;

       /*  If there was a second node, we want that node's blink to at 0. */

       if (hdr->flink)

           hdr->flink->blink = MCAPI_NULL;

       /* Clear the next and previous pointers.*/

       ent->flink = ent->blink = MCAPI_NULL;

   }

   /* Return a pointer to the removed node */

   return (ent);

}  /* mcapi_dequeue */