/*************************************************************************/ /*!
@File
@Title          Provides splay-trees.
@Copyright      Copyright (c) Imagination Technologies Ltd. All Rights Reserved
@Description    Implementation of splay-trees.
@License        Dual MIT/GPLv2

The contents of this file are subject to the MIT license as set out below.

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of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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all copies or substantial portions of the Software.

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the GNU General Public License Version 2 ("GPL") in which case the provisions
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and replace them with the notice and other provisions required by GPL as set
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not delete the provisions above, a recipient may use your version of this file
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This License is also included in this distribution in the file called
"MIT-COPYING".

EXCEPT AS OTHERWISE STATED IN A NEGOTIATED AGREEMENT: (A) THE SOFTWARE IS
PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
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 */ /**************************************************************************/

#include "allocmem.h" /* for OSMemAlloc / OSMemFree */
#include "osfunc.h" /* for OSMemFree */
#include "pvr_debug.h"
#include "uniq_key_splay_tree.h"

/**
 * This function performs a simple top down splay
 *
 * @param ui32Flags the flags that must splayed to the root (if possible).
 * @param psTree The tree to splay.
 * @return the resulting tree after the splay operation.
 */
IMG_INTERNAL
IMG_PSPLAY_TREE PVRSRVSplay (IMG_UINT32 ui32Flags, IMG_PSPLAY_TREE psTree) 
{
	IMG_SPLAY_TREE sTmp1;
	IMG_PSPLAY_TREE psLeft;
	IMG_PSPLAY_TREE psRight;
	IMG_PSPLAY_TREE psTmp2;

	if (psTree == NULL)
	{
		return NULL;
	}

	sTmp1.psLeft = NULL;
	sTmp1.psRight = NULL;

	psLeft = &sTmp1;
	psRight = &sTmp1;

	for (;;)
	{
		if (ui32Flags < psTree->ui32Flags)
		{
			if (psTree->psLeft == NULL)
			{
				break;
			}

			if (ui32Flags < psTree->psLeft->ui32Flags)
			{
				/* if we get to this point, we need to rotate right the tree */
				psTmp2 = psTree->psLeft;
				psTree->psLeft = psTmp2->psRight;
				psTmp2->psRight = psTree;
				psTree = psTmp2;
				if (psTree->psLeft == NULL)
				{
					break;
				}
			}

			/* if we get to this point, we need to link right */
			psRight->psLeft = psTree;
			psRight = psTree;
			psTree = psTree->psLeft;
		}
		else
		{
			if (ui32Flags > psTree->ui32Flags)
			{
				if (psTree->psRight == NULL)
				{
					break;
				}

				if (ui32Flags > psTree->psRight->ui32Flags)
				{
					/* if we get to this point, we need to rotate left the tree */
					psTmp2 = psTree->psRight;
					psTree->psRight = psTmp2->psLeft;
					psTmp2->psLeft = psTree;
					psTree = psTmp2;
					if (psTree->psRight == NULL)
					{
						break;
					}
				}

				/* if we get to this point, we need to link left */
				psLeft->psRight = psTree;
				psLeft = psTree;
				psTree = psTree->psRight;
			}
			else
			{
				break;
			}
		}
	}

	/* at this point re-assemble the tree */
	psLeft->psRight = psTree->psLeft;
	psRight->psLeft = psTree->psRight;
	psTree->psLeft = sTmp1.psRight;
	psTree->psRight = sTmp1.psLeft;
	return psTree;
}


/**
 * This function inserts a node into the Tree (unless it is already present, in
 * which case it is equivalent to performing only a splay operation
 *
 * @param ui32Flags the key of the new node
 * @param psTree The tree into which one wants to add a new node
 * @return The resulting with the node in it
 */
IMG_INTERNAL
IMG_PSPLAY_TREE PVRSRVInsert(IMG_UINT32 ui32Flags, IMG_PSPLAY_TREE psTree) 
{
	IMG_PSPLAY_TREE psNew;

	if (psTree != NULL)
	{
		psTree = PVRSRVSplay(ui32Flags, psTree);
		if (psTree->ui32Flags == ui32Flags)
		{
			return psTree;
		}
	}

	psNew = (IMG_PSPLAY_TREE) OSAllocMem(sizeof(IMG_SPLAY_TREE));
	if (psNew == NULL)
	{
		PVR_DPF ((PVR_DBG_ERROR, "Error: failed to allocate memory to add a node to the splay tree."));
		return NULL;
	}

	psNew->ui32Flags = ui32Flags;
	OSCachedMemSet(&(psNew->buckets[0]), 0, sizeof(psNew->buckets));

#if defined(PVR_CTZLL)
	psNew->bHasEltsMapping = ~(((IMG_ELTS_MAPPINGS) 1 << (sizeof(psNew->buckets) / (sizeof(psNew->buckets[0])))) - 1);
#endif

	if (psTree == NULL)
	{
		psNew->psLeft  = NULL;
		psNew->psRight = NULL;
		return psNew;
	}

	if (ui32Flags < psTree->ui32Flags)
	{
		psNew->psLeft  = psTree->psLeft;
		psNew->psRight = psTree;
		psTree->psLeft = NULL;
	}
	else 
	{
		psNew->psRight  = psTree->psRight;
		psNew->psLeft   = psTree;
		psTree->psRight = NULL;
	}

	return psNew;
}


/**
 * Deletes a node from the tree (unless it is not there, in which case it is
 * equivalent to a splay operation)
 * 
 * @param ui32Flags the value of the node to remove
 * @param psTree the tree into which the node must be removed 
 * @return the resulting tree
 */
IMG_INTERNAL
IMG_PSPLAY_TREE PVRSRVDelete(IMG_UINT32 ui32Flags, IMG_PSPLAY_TREE psTree)
{
	IMG_PSPLAY_TREE psTmp;
	if (psTree == NULL)
	{
		return NULL;
	}

	psTree = PVRSRVSplay(ui32Flags, psTree);
	if (ui32Flags == psTree->ui32Flags)
	{
		/* The value was present in the tree */
		if (psTree->psLeft == NULL)
		{
			psTmp = psTree->psRight;
		}
		else
		{
			psTmp = PVRSRVSplay(ui32Flags, psTree->psLeft);
			psTmp->psRight = psTree->psRight;
		}
		OSFreeMem(psTree);
		return psTmp;
	}

	/* the value was not present in the tree, so just return it as is (after the
	 * splay) */
	return psTree;
}


