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- Implement RtlGetElementGenericTable using ordered node/element.

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- The splay tree generic table package is now complete. (The AVL package was done by Art earlier).

svn path=/trunk/; revision=24546
This commit is contained in:
Alex Ionescu 2006-10-16 04:08:09 +00:00
parent a18f3458b2
commit f9a7faa6e5
1 changed files with 84 additions and 3 deletions
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87
reactos/lib/rtl/generictable.c
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@ -412,15 +412,96 @@ RtlEnumerateGenericTableLikeADirectory(IN PRTL_AVL_TABLE Table,
} }
/* /*
* @unimplemented * @implemented
*/ */
PVOID PVOID
NTAPI NTAPI
RtlGetElementGenericTable(IN PRTL_GENERIC_TABLE Table, RtlGetElementGenericTable(IN PRTL_GENERIC_TABLE Table,
IN ULONG I) IN ULONG I)
{ {
UNIMPLEMENTED; ULONG OrderedElement, ElementCount;
return 0; PLIST_ENTRY OrderedNode;
ULONG DeltaUp, DeltaDown;
ULONG NextI = I + 1;
/* Setup current accounting data */
OrderedNode = Table->OrderedPointer;
OrderedElement = Table->WhichOrderedElement;
ElementCount = Table->NumberGenericTableElements;
/* Sanity checks */
if ((I == MAXULONG) || (NextI > ElementCount)) return NULL;
/* Check if we already found the entry */
if (NextI == OrderedElement)
{
/* Return it */
return &((PTABLE_ENTRY_HEADER)CONTAINING_RECORD(OrderedNode,
TABLE_ENTRY_HEADER,
ListEntry))->UserData;
}
/* Now check if we're farther behind */
if (OrderedElement > NextI)
{
/* Find out if the distance is more then the half-way point */
if (NextI > (OrderedElement / 2))
{
/* Do the search backwards, since this takes less iterations */
DeltaDown = OrderedElement - NextI;
do
{
/* Get next node */
OrderedNode = OrderedNode->Blink;
} while (--DeltaDown);
}
else
{
/* Follow the list directly instead */
OrderedNode = &Table->InsertOrderList;
do
{
/* Get next node */
OrderedNode = OrderedNode->Flink;
} while (--NextI);
}
}
else
{
/* We are farther ahead, calculate distances */
DeltaUp = NextI - OrderedElement;
DeltaDown = (ElementCount - NextI) + 1;
/* Check if the up distance is smaller then the down distance */
if (DeltaUp <= DeltaDown)
{
/* Do the search forwards, since this takes less iterations */
do
{
/* Get next node */
OrderedNode = OrderedNode->Blink;
} while (--DeltaUp);
}
else
{
/* Do the search downwards, since this takes less iterations */
OrderedNode = &Table->InsertOrderList;
do
{
/* Get next node */
OrderedNode = OrderedNode->Blink;
} while (--DeltaDown);
}
}
/* Got the element, save it */
Table->OrderedPointer = OrderedNode;
Table->WhichOrderedElement = NextI;
/* Return the element */
return &((PTABLE_ENTRY_HEADER)CONTAINING_RECORD(OrderedNode,
TABLE_ENTRY_HEADER,
ListEntry))->UserData;
} }
/* AVL FUNCTIONS *************************************************************/ /* AVL FUNCTIONS *************************************************************/