//Copyright Paul Reiche, Fred Ford. 1992-2002

/*
 *  This program is free software; 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 program is distributed in the hope that it will be useful,
 *  but 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.
 */

#ifndef _DISPLIST_H
#define _DISPLIST_H

#include <assert.h>
#include "port.h"
#include "libs/compiler.h"
#include "libs/memlib.h"

// Note that we MUST use the QUEUE_TABLE variant at this time, because
// certain gameplay elements depend on it. Namely, the maximum number
// of HyperSpace encounter globes chasing the player is defined by the
// allocated size of the encounter_q. If switched to non-table variant,
// the max number of encounters will be virtually unlimited the way the
// code works now.
#define QUEUE_TABLE

typedef void* QUEUE_HANDLE;

typedef UWORD OBJ_SIZE;
typedef QUEUE_HANDLE HLINK;

typedef struct link
{
	// Every queue element of any queue must have these
	// two as the first members
	HLINK pred;
	HLINK succ;
} LINK;

typedef struct /* queue */
{
	HLINK head;
	HLINK tail;
#ifdef QUEUE_TABLE
	BYTE  *pq_tab;
	HLINK free_list;
#endif
	COUNT object_size;
#ifdef QUEUE_TABLE
	BYTE num_objects;
#endif /* QUEUE_TABLE */
} QUEUE;

#ifdef QUEUE_TABLE

extern HLINK AllocLink (QUEUE *pq);
extern void FreeLink (QUEUE *pq, HLINK hLink);

static inline LINK *
LockLink (const QUEUE *pq, HLINK h)
{
	if (h) // Apparently, h==0 is OK
	{	// Make sure the link is actually in our queue!
		assert (pq->pq_tab && (BYTE*)h >= pq->pq_tab &&
				(BYTE*)h < pq->pq_tab + pq->object_size * pq->num_objects);
	}
	return (LINK*)h;
}

static inline void
UnlockLink (const QUEUE *pq, HLINK h)
{
	if (h) // Apparently, h==0 is OK
	{	// Make sure the link is actually in our queue!
		assert (pq->pq_tab && (BYTE*)h >= pq->pq_tab &&
				(BYTE*)h < pq->pq_tab + pq->object_size * pq->num_objects);
	}
}

#define GetFreeList(pq) (pq)->free_list
#define SetFreeList(pq, h) (pq)->free_list = (h)
#define AllocQueueTab(pq,n) \
		((pq)->pq_tab = HMalloc (((COUNT)(pq)->object_size * \
		(COUNT)((pq)->num_objects = (BYTE)(n)))))
#define FreeQueueTab(pq) HFree ((pq)->pq_tab); (pq)->pq_tab = NULL
#define SizeQueueTab(pq) (COUNT)((pq)->num_objects)
#define GetLinkAddr(pq,i) (HLINK)((pq)->pq_tab + ((pq)->object_size * ((i) - 1)))
#else /* !QUEUE_TABLE */
#define AllocLink(pq)     (HLINK)HMalloc ((pq)->object_size)
#define LockLink(pq, h)   ((LINK*)(h))
#define UnlockLink(pq, h) ((void)(h))
#define FreeLink(pq,h)    HFree (h)
#endif /* QUEUE_TABLE */

#define SetLinkSize(pq,s) ((pq)->object_size = (COUNT)(s))
#define GetLinkSize(pq) (COUNT)((pq)->object_size)
#define GetHeadLink(pq) ((pq)->head)
#define SetHeadLink(pq,h) ((pq)->head = (h))
#define GetTailLink(pq) ((pq)->tail)
#define SetTailLink(pq,h) ((pq)->tail = (h))
#define _GetPredLink(lpE) ((lpE)->pred)
#define _SetPredLink(lpE,h) ((lpE)->pred = (h))
#define _GetSuccLink(lpE) ((lpE)->succ)
#define _SetSuccLink(lpE,h) ((lpE)->succ = (h))

extern BOOLEAN InitQueue (QUEUE *pq, COUNT num_elements, OBJ_SIZE size);
extern BOOLEAN UninitQueue (QUEUE *pq);
extern void ReinitQueue (QUEUE *pq);
extern void PutQueue (QUEUE *pq, HLINK hLink);
extern void InsertQueue (QUEUE *pq, HLINK hLink, HLINK hRefLink);
extern void RemoveQueue (QUEUE *pq, HLINK hLink);
extern COUNT CountLinks (QUEUE *pq);
void ForAllLinks(QUEUE *pq, void (*callback)(LINK *, void *), void *arg);

#endif /* _DISPLIST_H */

