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/*

 * Copyright (c) 2009 Lukas Mejdrech

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.

 */

/** @addtogroup packet

 *  @{

 */

/** @file

 *  Packet map and queue implementation.

 *  This file has to be compiled with both the packet server and the client.

 */

#include <errno.h>

#include <futex.h>

#include <malloc.h>

//#include <stdio.h>

#include <string.h>

#include <sys/mman.h>

#include "../../err.h"

#include "../generic_field.h"

#include "packet_header.h"

#include "packet.h"

// TODO power of 2 aritmetic => div and mod speedup?

/** Packet map page size.

 */

#define PACKET_MAP_SIZE 100

/** Returns the packet map page index.

 *  @param packet_id The packet identifier.

 */

#define PACKET_MAP_PAGE( packet_id )    ((( packet_id ) - 1 ) / PACKET_MAP_SIZE )

/** Returns the packet index in the corresponding packet map page.

 *  @param packet_id The packet identifier.

 */

#define PACKET_MAP_INDEX( packet_id )   ((( packet_id ) - 1 ) % PACKET_MAP_SIZE )

/** Type definition of the packet map page.

 */

typedef packet_t packet_map_t[ PACKET_MAP_SIZE ];

/** Type definition of the packet map page pointer.

 */

typedef packet_map_t * packet_map_ref;

/** Packet map.

 *  Maps packet identifiers to the packet references.

 *  @see generic_field.h

 */

GENERIC_FIELD_DECLARE( gpm, packet_map_t );

/** Releases the packet.

 *  @param packet The packet to be released. Input parameter.

 *  @returns EOK on success.

 *  @returns EINVAL if the packet is not valid.

 */

int packet_destroy( packet_t packet );

/** Packet map global data.

 */

static struct{

    /** Safety lock.

     *  Used as a mutex.

     */

    futex_t lock;

    /** Packet map.

     */

    gpm_t   packet_map;

} pm_globals;

GENERIC_FIELD_IMPLEMENT( gpm, packet_map_t );

int packet_destroy( packet_t packet ){

    if( ! packet_is_valid( packet )) return EINVAL;

    return munmap( packet, packet->length );

}

int pm_init( void ){

    ERROR_DECLARE;

    // start locked

    futex_initialize( & pm_globals.lock, 0 );

    ERROR_PROPAGATE( gpm_initialize( & pm_globals.packet_map ));

    // release the lock

    futex_up( & pm_globals.lock );

    return EOK;

}

packet_t pm_find( packet_id_t packet_id ){

    packet_map_ref map;

    packet_t packet;

    if( ! packet_id ) return NULL;

    futex_down( & pm_globals.lock );

    if( packet_id > PACKET_MAP_SIZE * gpm_count( & pm_globals.packet_map )){

        futex_up( & pm_globals.lock );

        return NULL;

    }

    map = gpm_get_index( & pm_globals.packet_map, PACKET_MAP_PAGE( packet_id ));

    if( ! map ){

        futex_up( & pm_globals.lock );

        return NULL;

    }

    packet = ( * map )[ PACKET_MAP_INDEX( packet_id ) ];

    futex_up( & pm_globals.lock );

    return packet;

}

int pm_add( packet_t packet ){

    ERROR_DECLARE;

    packet_map_ref map;

    if( ! packet_is_valid( packet )) return EINVAL;

    futex_down( & pm_globals.lock );

    if( PACKET_MAP_PAGE( packet->packet_id ) < gpm_count( & pm_globals.packet_map )){

        map = gpm_get_index( & pm_globals.packet_map, PACKET_MAP_PAGE( packet->packet_id ));

    }else{

        do{

            map = ( packet_map_ref ) malloc( sizeof( packet_map_t ));

            if( ! map ){

                futex_up( & pm_globals.lock );

                return ENOMEM;

            }

            memset( map, 0, sizeof( packet_map_t ));

            if(( ERROR_CODE = gpm_add( & pm_globals.packet_map, map )) < 0 ){

                free( map );

                futex_up( & pm_globals.lock );

                return ERROR_CODE;

            }

        }while( PACKET_MAP_PAGE( packet->packet_id ) >= gpm_count( & pm_globals.packet_map ));

    }

    ( * map )[ PACKET_MAP_INDEX( packet->packet_id ) ] = packet;

    futex_up( & pm_globals.lock );

    return EOK;

}

void pm_destroy( void ){

    int count;

    int index;

    packet_map_ref map;

    packet_t packet;

    futex_down( & pm_globals.lock );

    count = gpm_count( & pm_globals.packet_map );

    while( count > 0 ){

        map = gpm_get_index( & pm_globals.packet_map, count - 1 );

        for( index = PACKET_MAP_SIZE - 1; index >= 0; -- index ){

            packet = ( * map )[ index ];

            if( packet_is_valid( packet )){

                munmap( packet, packet->length );

            }

        }

    }

    gpm_destroy( & pm_globals.packet_map );

    // leave locked

}

packet_t pq_add( packet_t first, packet_t packet, int order, size_t metric ){

    packet_t    item;

    if( ! packet_is_valid( packet )) return NULL;

    pq_set( packet, order, metric );

    if( packet_is_valid( first )){

        item = first;

        do{

            if( item->order < order ){

                if( item->next ){

                    item = pm_find( item->next );

                }else{

                    item->next = packet->packet_id;

                    packet->previous = item->packet_id;

                    return first;

                }

            }else{

                packet->previous = item->previous;

                packet->next = item->packet_id;

                item->previous = packet->packet_id;

                item = pm_find( packet->previous );

                if( item ) item->next = packet->packet_id;

                return item;

            }

        }while( packet_is_valid( item ));

    }

    return packet;

}

packet_t pq_detach( packet_t packet ){

    packet_t next;

    packet_t previous;

    if( ! packet_is_valid( packet )) return NULL;

    next = pm_find( packet->next );

    if( next ){

        next->previous = packet->previous;

        previous = pm_find( next->previous );

        if( previous ){

            previous->next = next->packet_id;

        }

    }

    packet->previous = 0;

    packet->next = 0;

    return next;

}

int pq_set( packet_t packet, int order, size_t metric ){

    if( ! packet_is_valid( packet )) return EINVAL;

    packet->order = order;

    packet->metric = metric;

    return EOK;

}

void pq_destroy( packet_t first, void ( * packet_release )( packet_t packet )){

    packet_t    actual;

    packet_t    next;

    actual = first;

    while( packet_is_valid( actual )){

        next = pm_find( actual->next );

        actual->next = 0;

        actual->previous = 0;

        if( packet_release ) packet_release( actual );

        actual = next;

    }

}

/** @}

 */