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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&nbsp;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;
    }
}

/** @}
 */