openldap/libraries/libmdb/midl.c

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/** @file midl.c
* @brief ldap bdb back-end ID List functions */
/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
*
* Copyright 2000-2011 The OpenLDAP Foundation.
* 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>.
*/
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#include <string.h>
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#include <sys/types.h>
#include <assert.h>
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#include "midl.h"
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/** @defgroup internal MDB Internals
* @{
*/
/** @defgroup idls ID List Management
* @{
*/
#define CMP(x,y) ( (x) < (y) ? -1 : (x) > (y) )
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#if 0
static unsigned mdb_midl_search( IDL ids, ID id )
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{
/*
* 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 = 0;
int val = 0;
unsigned n = ids[0];
while( 0 < n ) {
int pivot = n >> 1;
cursor = base + pivot;
val = CMP( ids[cursor + 1], id );
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if( val < 0 ) {
n = pivot;
} else if ( val > 0 ) {
base = cursor + 1;
n -= pivot + 1;
} else {
return cursor + 1;
}
}
if( val > 0 ) {
return cursor + 2;
} else {
return cursor + 1;
}
}
int mdb_midl_insert( IDL ids, ID id )
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{
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unsigned x, i;
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if (MDB_IDL_IS_RANGE( ids )) {
/* if already in range, treat as a dup */
if (id >= MDB_IDL_FIRST(ids) && id <= MDB_IDL_LAST(ids))
return -1;
if (id < MDB_IDL_FIRST(ids))
ids[1] = id;
else if (id > MDB_IDL_LAST(ids))
ids[2] = id;
return 0;
}
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x = mdb_midl_search( ids, id );
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assert( x > 0 );
if( x < 1 ) {
/* internal error */
return -2;
}
if ( x <= ids[0] && ids[x] == id ) {
/* duplicate */
assert(0);
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return -1;
}
if ( ++ids[0] >= MDB_IDL_DB_MAX ) {
if( id < ids[1] ) {
ids[1] = id;
ids[2] = ids[ids[0]-1];
} else if ( ids[ids[0]-1] < id ) {
ids[2] = id;
} else {
ids[2] = ids[ids[0]-1];
}
ids[0] = NOID;
} else {
/* insert id */
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for (i=ids[0]; i>x; i--)
ids[i] = ids[i-1];
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ids[x] = id;
}
return 0;
}
#endif
int mdb_midl_append( IDL ids, ID id )
{
/* Too big? */
if (ids[0] >= MDB_IDL_UM_SIZE)
return -1;
ids[0]++;
ids[ids[0]] = id;
return 0;
}
/* Quicksort + Insertion sort for small arrays */
#define SMALL 8
#define SWAP(a,b) itmp=(a);(a)=(b);(b)=itmp
void
mdb_midl_sort( ID *ids )
{
int istack[16*sizeof(int)];
int i,j,k,l,ir,jstack;
ID a, itmp;
ir = 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 */
SWAP(ids[k], ids[l+1]);
if (ids[l] < ids[ir]) {
SWAP(ids[l], ids[ir]);
}
if (ids[l+1] < ids[ir]) {
SWAP(ids[l+1], ids[ir]);
}
if (ids[l] < ids[l+1]) {
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;
SWAP(ids[i],ids[j]);
}
ids[l+1] = ids[j];
ids[j] = a;
jstack += 2;
if (ir-i+1 >= j-1) {
istack[jstack] = ir;
istack[jstack-1] = i;
ir = j-1;
} else {
istack[jstack] = j-1;
istack[jstack-1] = l;
l = i;
}
}
}
}
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unsigned mdb_mid2l_search( ID2L ids, ID id )
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{
/*
* 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 = 0;
int val = 0;
unsigned n = ids[0].mid;
while( 0 < n ) {
int pivot = n >> 1;
cursor = base + pivot;
val = CMP( id, ids[cursor + 1].mid );
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if( val < 0 ) {
n = pivot;
} else if ( val > 0 ) {
base = cursor + 1;
n -= pivot + 1;
} else {
return cursor + 1;
}
}
if( val > 0 ) {
return cursor + 2;
} else {
return cursor + 1;
}
}
int mdb_mid2l_insert( ID2L ids, ID2 *id )
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{
unsigned x, i;
x = mdb_mid2l_search( ids, id->mid );
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assert( x > 0 );
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_DB_MAX ) {
/* too big */
return -2;
} else {
/* insert id */
ids[0].mid++;
for (i=ids[0].mid; i>x; i--)
ids[i] = ids[i-1];
ids[x] = *id;
}
return 0;
}
/** @} */
/** @} */