text: /**	@file midl.c
   *	@brief ldap bdb back-end ID List functions */
  /* $OpenLDAP$ */
  /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   *
   * Copyright 2000-2019 The OpenLDAP Foundation.
   * Portions Copyright 2001-2018 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>.
   */
  
  #include <limits.h>
  #include <string.h>
  #include <stdlib.h>
  #include <errno.h>
  #include <sys/types.h>
  #include "midl.h"
  
  /** @defgroup internal	LMDB Internals
   *	@{
   */
  /** @defgroup idls	ID List Management
   *	@{
   */
  #define CMP(x,y)	 ( (x) < (y) ? -1 : (x) > (y) )
  
  unsigned mdb_midl_search( MDB_IDL ids, MDB_ID id )
  {
  	/*
  	 * binary search of id in ids
  	 * if found, returns position of id
  	 * if not found, returns first position greater than id
  	 */
  	unsigned base = 0;
  	unsigned cursor = 1;
  	int val = 0;
  	unsigned n = ids[0];
  
  	while( 0 < n ) {
  		unsigned pivot = n >> 1;
  		cursor = base + pivot + 1;
  		val = CMP( ids[cursor], id );
  
  		if( val < 0 ) {
  			n = pivot;
  
  		} else if ( val > 0 ) {
  			base = cursor;
  			n -= pivot + 1;
  
  		} else {
  			return cursor;
  		}
  	}
  
  	if( val > 0 ) {
  		++cursor;
  	}
  	return cursor;
  }
  
  #if 0	/* superseded by append/sort */
  int mdb_midl_insert( MDB_IDL ids, MDB_ID id )
  {
  	unsigned x, i;
  
  	x = mdb_midl_search( ids, id );
  	assert( x > 0 );
  
  	if( x < 1 ) {
  		/* internal error */
  		return -2;
  	}
  
  	if ( x <= ids[0] && ids[x] == id ) {
  		/* duplicate */
  		assert(0);
  		return -1;
  	}
  
  	if ( ++ids[0] >= MDB_IDL_DB_MAX ) {
  		/* no room */
  		--ids[0];
  		return -2;
  
  	} else {
  		/* insert id */
  		for (i=ids[0]; i>x; i--)
  			ids[i] = ids[i-1];
  		ids[x] = id;
  	}
  
  	return 0;
  }
  #endif
  
  MDB_IDL mdb_midl_alloc(int num)
  {
  	MDB_IDL ids = malloc((num+2) * sizeof(MDB_ID));
  	if (ids) {
  		*ids++ = num;
  		*ids = 0;
  	}
  	return ids;
  }
  
  void mdb_midl_free(MDB_IDL ids)
  {
  	if (ids)
  		free(ids-1);
  }
  
  void mdb_midl_shrink( MDB_IDL *idp )
  {
  	MDB_IDL ids = *idp;
  	if (*(--ids) > MDB_IDL_UM_MAX &&
  		(ids = realloc(ids, (MDB_IDL_UM_MAX+2) * sizeof(MDB_ID))))
  	{
  		*ids++ = MDB_IDL_UM_MAX;
  		*idp = ids;
  	}
  }
  
  static int mdb_midl_grow( MDB_IDL *idp, int num )
  {
  	MDB_IDL idn = *idp-1;
  	/* grow it */
  	idn = realloc(idn, (*idn + num + 2) * sizeof(MDB_ID));
  	if (!idn)
  		return ENOMEM;
  	*idn++ += num;
  	*idp = idn;
  	return 0;
  }
  
  int mdb_midl_need( MDB_IDL *idp, unsigned num )
  {
  	MDB_IDL ids = *idp;
  	num += ids[0];
  	if (num > ids[-1]) {
  		num = (num + num/4 + (256 + 2)) & -256;
  		if (!(ids = realloc(ids-1, num * sizeof(MDB_ID))))
  			return ENOMEM;
  		*ids++ = num - 2;
  		*idp = ids;
  	}
  	return 0;
  }
  
  int mdb_midl_append( MDB_IDL *idp, MDB_ID id )
  {
  	MDB_IDL ids = *idp;
  	/* Too big? */
  	if (ids[0] >= ids[-1]) {
  		if (mdb_midl_grow(idp, MDB_IDL_UM_MAX))
  			return ENOMEM;
  		ids = *idp;
  	}
  	ids[0]++;
  	ids[ids[0]] = id;
  	return 0;
  }
  
  int mdb_midl_append_list( MDB_IDL *idp, MDB_IDL app )
  {
  	MDB_IDL ids = *idp;
  	/* Too big? */
  	if (ids[0] + app[0] >= ids[-1]) {
  		if (mdb_midl_grow(idp, app[0]))
  			return ENOMEM;
  		ids = *idp;
  	}
  	memcpy(&ids[ids[0]+1], &app[1], app[0] * sizeof(MDB_ID));
  	ids[0] += app[0];
  	return 0;
  }
  
  int mdb_midl_append_range( MDB_IDL *idp, MDB_ID id, unsigned n )
  {
  	MDB_ID *ids = *idp, len = ids[0];
  	/* Too big? */
  	if (len + n > ids[-1]) {
  		if (mdb_midl_grow(idp, n | MDB_IDL_UM_MAX))
  			return ENOMEM;
  		ids = *idp;
  	}
  	ids[0] = len + n;
  	ids += len;
  	while (n)
  		ids[n--] = id++;
  	return 0;
  }
  
  void mdb_midl_xmerge( MDB_IDL idl, MDB_IDL merge )
  {
  	MDB_ID old_id, merge_id, i = merge[0], j = idl[0], k = i+j, total = k;
  	idl[0] = (MDB_ID)-1;		/* delimiter for idl scan below */
  	old_id = idl[j];
  	while (i) {
  		merge_id = merge[i--];
  		for (; old_id < merge_id; old_id = idl[--j])
  			idl[k--] = old_id;
  		idl[k--] = merge_id;
  	}
  	idl[0] = total;
  }
  
  /* Quicksort + Insertion sort for small arrays */
  
  #define SMALL	8
  #define	MIDL_SWAP(a,b)	{ itmp=(a); (a)=(b); (b)=itmp; }
  
  void
  mdb_midl_sort( MDB_IDL ids )
  {
  	/* Max possible depth of int-indexed tree * 2 items/level */
  	int istack[sizeof(int)*CHAR_BIT * 2];
  	int i,j,k,l,ir,jstack;
  	MDB_ID a, itmp;
  
  	ir = (int)ids[0];
  	l = 1;
  	jstack = 0;
  	for(;;) {
  		if (ir - l < SMALL) {	/* Insertion sort */
  			for (j=l+1;j<=ir;j++) {
  				a = ids[j];
  				for (i=j-1;i>=1;i--) {
  					if (ids[i] >= a) break;
  					ids[i+1] = ids[i];
  				}
  				ids[i+1] = a;
  			}
  			if (jstack == 0) break;
  			ir = istack[jstack--];
  			l = istack[jstack--];
  		} else {
  			k = (l + ir) >> 1;	/* Choose median of left, center, right */
  			MIDL_SWAP(ids[k], ids[l+1]);
  			if (ids[l] < ids[ir]) {
  				MIDL_SWAP(ids[l], ids[ir]);
  			}
  			if (ids[l+1] < ids[ir]) {
  				MIDL_SWAP(ids[l+1], ids[ir]);
  			}
  			if (ids[l] < ids[l+1]) {
  				MIDL_SWAP(ids[l], ids[l+1]);
  			}
  			i = l+1;
  			j = ir;
  			a = ids[l+1];
  			for(;;) {
  				do i++; while(ids[i] > a);
  				do j--; while(ids[j] < a);
  				if (j < i) break;
  				MIDL_SWAP(ids[i],ids[j]);
  			}
  			ids[l+1] = ids[j];
  			ids[j] = a;
  			jstack += 2;
  			if (ir-i+1 >= j-l) {
  				istack[jstack] = ir;
  				istack[jstack-1] = i;
  				ir = j-1;
  			} else {
  				istack[jstack] = j-1;
  				istack[jstack-1] = l;
  				l = i;
  			}
  		}
  	}
  }
  
  unsigned mdb_mid2l_search( MDB_ID2L ids, MDB_ID id )
  {
  	/*
  	 * binary search of id in ids
  	 * if found, returns position of id
  	 * if not found, returns first position greater than id
  	 */
  	unsigned base = 0;
  	unsigned cursor = 1;
  	int val = 0;
  	unsigned n = (unsigned)ids[0].mid;
  
  	while( 0 < n ) {
  		unsigned pivot = n >> 1;
  		cursor = base + pivot + 1;
  		val = CMP( id, ids[cursor].mid );
  
  		if( val < 0 ) {
  			n = pivot;
  
  		} else if ( val > 0 ) {
  			base = cursor;
  			n -= pivot + 1;
  
  		} else {
  			return cursor;
  		}
  	}
  
  	if( val > 0 ) {
  		++cursor;
  	}
  	return cursor;
  }
  
  int mdb_mid2l_insert( MDB_ID2L ids, MDB_ID2 *id )
  {
  	unsigned x, i;
  
  	x = mdb_mid2l_search( ids, id->mid );
  
  	if( x < 1 ) {
  		/* internal error */
  		return -2;
  	}
  
  	if ( x <= ids[0].mid && ids[x].mid == id->mid ) {
  		/* duplicate */
  		return -1;
  	}
  
  	if ( ids[0].mid >= MDB_IDL_UM_MAX ) {
  		/* too big */
  		return -2;
  
  	} else {
  		/* insert id */
  		ids[0].mid++;
  		for (i=(unsigned)ids[0].mid; i>x; i--)
  			ids[i] = ids[i-1];
  		ids[x] = *id;
  	}
  
  	return 0;
  }
  
  int mdb_mid2l_append( MDB_ID2L ids, MDB_ID2 *id )
  {
  	/* Too big? */
  	if (ids[0].mid >= MDB_IDL_UM_MAX) {
  		return -2;
  	}
  	ids[0].mid++;
  	ids[ids[0].mid] = *id;
  	return 0;
  }
  
  /** @} */
  /** @} */
  