/**	@file midl.h
 *	@brief LMDB ID List header file.
 *
 *	This file was originally part of back-bdb but has been
 *	modified for use in libmdb. Most of the macros defined
 *	in this file are unused, just left over from the original.
 *
 *	This file is only used internally in libmdb and its definitions
 *	are not exposed publicly.
 */
/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
 *
 * Copyright 2000-2021 The OpenLDAP Foundation.
 * Portions Copyright 2001-2021 Howard Chu, Symas Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted only as authorized by the OpenLDAP
 * Public License.
 *
 * A copy of this license is available in the file LICENSE in the
 * top-level directory of the distribution or, alternatively, at
 * <http://www.OpenLDAP.org/license.html>.
 */

#ifndef _MDB_MIDL_H_
#define _MDB_MIDL_H_

#include "lmdb.h"

#ifdef __cplusplus
extern "C" {
#endif

/** @defgroup internal	LMDB Internals
 *	@{
 */

/** @defgroup idls	ID List Management
 *	@{
 */
/** A generic unsigned ID number. These were entryIDs in back-bdb.
 *	Preferably it should have the same size as a pointer.
 */
typedef mdb_size_t MDB_ID;

/** An IDL is an ID List, a sorted array of IDs. The first
 * element of the array is a counter for how many actual
 * IDs are in the list. In the original back-bdb code, IDLs are
 * sorted in ascending order. For libmdb IDLs are sorted in
 * descending order.
 */
typedef MDB_ID* MDB_IDL;

/* IDL sizes - likely should be even bigger
 *   limiting factors: sizeof(ID), thread stack size
 */
#ifndef MDB_IDL_LOGN
#define MDB_IDL_LOGN 16 /* DB_SIZE is 2^16, UM_SIZE is 2^17 */
#endif
#define MDB_IDL_DB_SIZE (1 << MDB_IDL_LOGN)
#define MDB_IDL_UM_SIZE (1 << (MDB_IDL_LOGN + 1))

#define MDB_IDL_DB_MAX (MDB_IDL_DB_SIZE - 1)
#define MDB_IDL_UM_MAX (MDB_IDL_UM_SIZE - 1)

#define MDB_IDL_SIZEOF(ids) (((ids)[0] + 1) * sizeof(MDB_ID))
#define MDB_IDL_IS_ZERO(ids) ((ids)[0] == 0)
#define MDB_IDL_CPY(dst, src) (memcpy(dst, src, MDB_IDL_SIZEOF(src)))
#define MDB_IDL_FIRST(ids) ((ids)[1])
#define MDB_IDL_LAST(ids) ((ids)[(ids)[0]])

/** Current max length of an #mdb_midl_alloc()ed IDL */
#define MDB_IDL_ALLOCLEN(ids) ((ids)[-1])

/** Append ID to IDL. The IDL must be big enough. */
#define mdb_midl_xappend(idl, id)             \
  do {                                        \
    MDB_ID *xidl = (idl), xlen = ++(xidl[0]); \
    xidl[xlen] = (id);                        \
  } while (0)

/** Search for an ID in an IDL.
 * @param[in] ids	The IDL to search.
 * @param[in] id	The ID to search for.
 * @return	The index of the first ID greater than or equal to \b id.
 */
unsigned mdb_midl_search(MDB_IDL ids, MDB_ID id);

/** Allocate an IDL.
 * Allocates memory for an IDL of the given size.
 * @return	IDL on success, NULL on failure.
 */
MDB_IDL mdb_midl_alloc(int num);

/** Free an IDL.
 * @param[in] ids	The IDL to free.
 */
void mdb_midl_free(MDB_IDL ids);

/** Shrink an IDL.
 * Return the IDL to the default size if it has grown larger.
 * @param[in,out] idp	Address of the IDL to shrink.
 */
void mdb_midl_shrink(MDB_IDL* idp);

/** Make room for num additional elements in an IDL.
 * @param[in,out] idp	Address of the IDL.
 * @param[in] num	Number of elements to make room for.
 * @return	0 on success, ENOMEM on failure.
 */
int mdb_midl_need(MDB_IDL* idp, unsigned num);

/** Append an ID onto an IDL.
 * @param[in,out] idp	Address of the IDL to append to.
 * @param[in] id	The ID to append.
 * @return	0 on success, ENOMEM if the IDL is too large.
 */
int mdb_midl_append(MDB_IDL* idp, MDB_ID id);

/** Append an IDL onto an IDL.
 * @param[in,out] idp	Address of the IDL to append to.
 * @param[in] app	The IDL to append.
 * @return	0 on success, ENOMEM if the IDL is too large.
 */
int mdb_midl_append_list(MDB_IDL* idp, MDB_IDL app);

/** Append an ID range onto an IDL.
 * @param[in,out] idp	Address of the IDL to append to.
 * @param[in] id	The lowest ID to append.
 * @param[in] n		Number of IDs to append.
 * @return	0 on success, ENOMEM if the IDL is too large.
 */
int mdb_midl_append_range(MDB_IDL* idp, MDB_ID id, unsigned n);

/** Merge an IDL onto an IDL. The destination IDL must be big enough.
 * @param[in] idl	The IDL to merge into.
 * @param[in] merge	The IDL to merge.
 */
void mdb_midl_xmerge(MDB_IDL idl, MDB_IDL merge);

/** Sort an IDL.
 * @param[in,out] ids	The IDL to sort.
 */
void mdb_midl_sort(MDB_IDL ids);

/** An ID2 is an ID/pointer pair.
 */
typedef struct MDB_ID2 {
  MDB_ID mid; /**< The ID */
  void* mptr; /**< The pointer */
} MDB_ID2;

/** An ID2L is an ID2 List, a sorted array of ID2s.
 * The first element's \b mid member is a count of how many actual
 * elements are in the array. The \b mptr member of the first element is unused.
 * The array is sorted in ascending order by \b mid.
 */
typedef MDB_ID2* MDB_ID2L;

/** Search for an ID in an ID2L.
 * @param[in] ids	The ID2L to search.
 * @param[in] id	The ID to search for.
 * @return	The index of the first ID2 whose \b mid member is greater than
 * or equal to \b id.
 */
unsigned mdb_mid2l_search(MDB_ID2L ids, MDB_ID id);

/** Insert an ID2 into a ID2L.
 * @param[in,out] ids	The ID2L to insert into.
 * @param[in] id	The ID2 to insert.
 * @return	0 on success, -1 if the ID was already present in the ID2L.
 */
int mdb_mid2l_insert(MDB_ID2L ids, MDB_ID2* id);

/** Append an ID2 into a ID2L.
 * @param[in,out] ids	The ID2L to append into.
 * @param[in] id	The ID2 to append.
 * @return	0 on success, -2 if the ID2L is too big.
 */
int mdb_mid2l_append(MDB_ID2L ids, MDB_ID2* id);

#ifdef MDB_VL32
typedef struct MDB_ID3 {
  MDB_ID mid; /**< The ID */
  void* mptr; /**< The pointer */
  unsigned int mcnt; /**< Number of pages */
  unsigned int mref; /**< Refcounter */
} MDB_ID3;

typedef MDB_ID3* MDB_ID3L;

unsigned mdb_mid3l_search(MDB_ID3L ids, MDB_ID id);
int mdb_mid3l_insert(MDB_ID3L ids, MDB_ID3* id);

#endif /* MDB_VL32 */
/** @} */
/** @} */
#ifdef __cplusplus
}
#endif
#endif /* _MDB_MIDL_H_ */