/**
 *      @file    pslist.h
 *      @version $Format:%h%d$
 *
 *      List utilities.
 */
/*
 *      Copyright (c) 2013-2018 Rambus Inc.
 *      Copyright (c) PeerSec Networks, 2002-2011
 *      All Rights Reserved
 *
 *      The latest version of this code is available at http://www.matrixssl.org
 *
 *      This software is open source; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This General Public License does NOT permit incorporating this software
 *      into proprietary programs.  If you are unable to comply with the GPL, a
 *      commercial license for this software may be purchased from Rambus Inc at
 *      http://www.rambus.com/
 *
 *      This program is distributed in WITHOUT ANY WARRANTY; without even the
 *      implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *      See the GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *      http://www.gnu.org/copyleft/gpl.html
 */
/******************************************************************************/

#ifndef _h_PS_LIST
# define _h_PS_LIST

#include "osdep-types.h"

/********************************** Defines ***********************************/
/*
 *      Fast circular doubly-linked list and branchless macro-functions.
 *      Provides a struct-independent way to have a small head and hang a list
 *      of structs off of it. Examples of use:
 *
 *      typedef struct {
 *              int bar;
 *              DLListEntry List;
 *      } foo;
 *
 *  Define foo list head:
 *      DLListEntry FooListHead;
 *
 *  Init for list head:
 *      DLListInit(&FooListHead);
 *
 *      Define and init list head:
 *              DEFINE_DLLIST(FooListHead);
 *                      or
 *              static DEFINE_DLLIST(FooListHead);
 *
 *  Insert *pMyFoo after the head:
 *      foo *pMyFoo;
 *      pMyFoo = Malloc(sizeof(foo));
 *      DLListInsertHead(&FooListHead, &pMyFoo->List);
 *
 *  Do the same but place at tail:
 *      DLListInsertTail(&FooListHead, &pMyFoo->List);
 *
 *  Given a foo that you know is in a list, detach it from the list:
 *      DLListRemove(&pMyFoo->List);
 *
 *  Detach and return the list entry for the head item:
 *      DLListEntry *pList;
 *      pList = DLListGetHead(&FooListHead);
 *      pMyFoo = DLListGetContainer(pList, foo, List);
 *
 *  Iterate the entire list:
 *      DLListEntry *pList;
 *      pList = FooListHead.pNext;
 *      while (pList != &FooListHead) {
 *          pCurFoo = DLListGetContainer(pList, foo, List);
 *          ... (do something with the current foo)
 *          pList = pList->pNext;
 *      }
 *
 *  Iterate the entire list, removing each item (e.g. on all-list destruction):
 *      DLListEntry *pList;
 *      while (!DLListIsEmpty(&FooListHead)) {
 *          pList = DLListGetHead(&FooListHead);
 *          pMyFoo = DLListGetContainer(pList, foo, List);
 *          DestroyFoo(pMyFoo);
 *          Free(pMyFoo);
 *      }
 */
typedef struct _DLListEntry
{
    struct _DLListEntry *pNext, *pPrev;
} DLListEntry;

# define DEFINE_DLLIST(x) DLListEntry x = { .pNext = &x, .pPrev = &x };

# define DLListInit(__pList)  \
    (__pList)->pNext = (__pList)->pPrev = (__pList)

/* Inserts an item as the first item of the list */
# define DLListInsertHead(__pHead, __pNode) {  \
        psAssert((__pHead) != (__pNode));  \
        (__pNode)->pNext = (__pHead)->pNext;  \
        (__pNode)->pPrev = (__pHead);  \
        (__pHead)->pNext->pPrev = (__pNode);  \
        (__pHead)->pNext = (__pNode);  \
}

/* Inserts an item as the last in the list */
# define DLListInsertTail(__pHead, __pNode) {  \
        psAssert((__pHead) != (__pNode));  \
        (__pNode)->pNext = (__pHead);  \
        (__pNode)->pPrev = (__pHead)->pPrev;  \
        (__pHead)->pPrev->pNext = (__pNode);  \
        (__pHead)->pPrev = (__pNode);  \
}

/* Detaches node from current position in the list. */
# define DLListRemove(__pNode) {  \
        (__pNode)->pNext->pPrev = (__pNode)->pPrev;  \
        (__pNode)->pPrev->pNext = (__pNode)->pNext;  \
}

# define DLListIsEmpty(__pHead) ((__pHead)->pNext == (__pHead))

/*
    Gets the pointer to the containing object given the DLList pointer,
    the type name of the struct, and the name of the DLList field within
    the struct.
 */
# define DLListGetContainer(__pDLList, __ContainerType, __DLListFieldName)  \
    ((__ContainerType *) ((char *) (__pDLList) -  \
                          (long) (&((__ContainerType *) 0)->__DLListFieldName)))

/*
    Detaches first list item after the head and returns a pointer to it.
    List must not be empty.
 */
# define DLListGetHead(__pHead)  \
    (__pHead)->pNext;  \
    (__pHead)->pNext->pNext->pPrev = (__pHead);  \
    (__pHead)->pNext = (__pHead)->pNext->pNext;

/*
    Detaches list list item before the head and returns a pointer to it.
    List must not be empty.
 */
# define DLListGetTail(__pHead)  \
    (__pHead)->pPrev;  \
    (__pHead)->pPrev->pPrev->pNext = (__pHead);  \
    (__pHead)->pPrev = (__pHead)->pPrev->pPrev;

/******************************************************************************/
/*
    Simpler, single linked list
 */
typedef struct psList
{
    unsigned char *item;
    struct psList *next;
    psSize_t len;
} psList_t;

#endif /* _h_PS_LIST */
/******************************************************************************/