server/include/micropather.h

/*
Copyright (c) 2000-2003 Lee Thomason (www.grinninglizard.com)
Grinning Lizard Utilities.

This software is provided 'as-is', without any express or implied 
warranty. In no event will the authors be held liable for any 
damages arising from the use of this software.

Permission is granted to anyone to use this software for any 
purpose, including commercial applications, and to alter it and 
redistribute it freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must 
not claim that you wrote the original software. If you use this 
software in a product, an acknowledgment in the product documentation 
would be appreciated but is not required.

2. Altered source versions must be plainly marked as such, and 
must not be misrepresented as being the original software.

3. This notice may not be removed or altered from any source 
distribution.
*/


#ifndef GRINNINGLIZARD_MICROPATHER_INCLUDED
#define GRINNINGLIZARD_MICROPATHER_INCLUDED

/** @mainpage MicroPather
        
        MicroPather is a path finder and A* solver (astar or a-star) written in platform independent 
        C++ that can be easily integrated into existing code. MicroPather focuses on being a path 
        finding engine for video games but is a generic A* solver. MicroPather is open source, with 
        a license suitable for open source or commercial use.

        An overview of using MicroPather is in the <A HREF="../readme.htm">readme</A> or
        on the Grinning Lizard website: http://grinninglizard.com/micropather/
*/

#include <vector>
#include <list>
#include <assert.h>
#include <float.h>

#ifdef _DEBUG
        #ifndef DEBUG
                #define DEBUG
        #endif
#endif

#ifndef GRINLIZ_TYPES_INCLUDED
        #if defined(_MSC_VER) && (_MSC_VER >= 1400 )
                #include <stdlib.h>
                typedef uintptr_t               UPTR;
        #elif defined (__GNUC__) && (__GNUC__ >= 3 )
                #include <stdlib.h>
                typedef uintptr_t               UPTR;
        #else
                // Assume not 64 bit pointers. Get a new compiler.
                typedef unsigned UPTR;
        #endif
#endif

/*  USE_LIST and USE_BINARY_HASH change the some of details the pather algorithms. They
        are set optimally in my experiments, but different applications may benefit
        from a different combination of these #defines.
*/
#define USE_LIST
//#define USE_BINARY_HASH

namespace micropather
{
        const float FLT_BIG = FLT_MAX / 2.0f;   

        /**
                Used to pass the cost of states from the cliet application to MicroPather. This
                structure is copied in a vector.

                @sa AdjacentCost
        */
        struct StateCost
        {
                void* state;                    ///< The state as a void*
                float cost;                             ///< The cost to the state. Use FLT_MAX for infinite cost.
        };


        /**
                A pure abstract class used to define a set of callbacks. 
                The client application inherits from 
                this class, and the methods will be called when MicroPather::Solve() is invoked.

                The notion of a "state" is very important. It must have the following properties:
                - Unique
                - Unchanging (unless MicroPather::Reset() is called)

                If the client application represents states as objects, then the state is usually
                just the object cast to a void*. If the client application sees states as numerical
                values, (x,y) for example, then state is an encoding of these values. MicroPather
                never interprets or modifies the value of state.
        */
        class Graph
        {
          public:
                virtual ~Graph() {}
          
                /**
                        Return the least possible cost between 2 states. For example, if your pathfinding 
                        is based on distance, this is simply the straight distance between 2 points on the 
                        map. If you pathfinding is based on minimum time, it is the minimal travel time 
                        between 2 points given the best possible terrain.
                */
                virtual float LeastCostEstimate( void* stateStart, void* stateEnd ) = 0;

                /** 
                        Return the exact cost from the given state to all its neighboring states. This
                        may be called multiple times, or cached by the solver. It *must* return the same
                        exact values for every call to MicroPather::Solve(). It should generally be a simple,
                        fast function with no callbacks into the pather.
                */
                virtual void AdjacentCost( void* state, std::vector< micropather::StateCost > *adjacent ) = 0;

                /**
                        This function is only used in DEBUG mode - it dumps output to stdout. Since void* 
                        aren't really human readable, normally you print out some concise info (like "(1,2)") 
                        without an ending newline.

                        @note If you are using other grinning lizard utilities, you should use GLOUTPUT for output.
                */
                virtual void  PrintStateInfo( void* state ) = 0;
        };


        class PathNode;

        struct NodeCost
        {
                PathNode* node;
                float cost;
        };


        class PathNode
        {
                friend class none;      // Trashy trick to get rid of compiler warning, because
                                                // this class has a private constructor and destructor -
                                                // it can never be "new" or created on the stack, only
                                                // by special allocators.
          public:
                void Init(      unsigned _frame,
                                        void* _state,
                                        float _costFromStart, 
                                        float _estToGoal, 
                                        PathNode* _parent )
                {
                        state = _state;
                        costFromStart = _costFromStart;
                        estToGoal = _estToGoal;
                        totalCost = _costFromStart + _estToGoal;
                        parent = _parent;
                        frame = _frame;
                        numAdjacent = -1;
                        left = 0;
                        #ifdef USE_BINARY_HASH
                        right = 0;
                        #endif
                        #ifdef USE_LIST
                        next = 0;
                        prev = 0;
                        #endif
                        inOpen = 0;
                        inClosed = 0;
                }

                void Reuse( unsigned _frame, float _costFromStart, float _estToGoal, PathNode* _parent ) 
                {
                        costFromStart = _costFromStart;
                        estToGoal = _estToGoal;
                        parent = _parent;
                        frame = _frame;

                        inOpen = 0;
                        inClosed = 0;
                }

                void *state;                    // the client state
                float costFromStart;    // exact
                float estToGoal;                // estimated
                float totalCost;                // could be a function, but save some math.
                PathNode* parent;               // the parent is used to reconstruct the path
                unsigned frame;                 // unique id for this path, so the solver can distinguish
                                                                // correct from stale values

                enum {
                        /*
                                @enum MAX_CACHE. If you want to optimize "down deep" this is the way
                                to go. MAX_CACHE determines the number of adjacent nodes cached by 
                                MicroPather. If your nodes generally have 8 or 3 neighbors (common cases)
                                changing this may increase performance, sometimes dramatically.
                        */
                        MAX_CACHE = 4
                };
                // If there are 4 or less adjacent states, they will be cached as *nodes*.
                NodeCost adjacent[ MAX_CACHE ];
                int numAdjacent;                                        // -1  is unknown & needs to be queried
                                                                                        // 0-4 adjacent is known & in 'adjacent'
                                                                                        // 5+  known, but has to be queried from Graph

                PathNode* left;                 // Binary tree, where the 'state' is what is being compared.
                                                                // Also used as a "next" pointer for memory layout.
                #ifdef USE_BINARY_HASH
                PathNode* right;
                #endif
                #ifdef USE_LIST
                PathNode *next, *prev;
                #endif

                unsigned inOpen:1;
                unsigned inClosed:1;

                #ifdef USE_LIST
                void Unlink() {
                        next->prev = prev;
                        prev->next = next;
                        next = prev = 0;
                }
                void AddBefore( PathNode* addThis ) {
                        addThis->next = this;
                        addThis->prev = prev;
                        prev->next = addThis;
                        prev = addThis;
                }
                #ifdef DEBUG
                void CheckList()
                {
                        assert( totalCost == FLT_MAX );
                        for( PathNode* it = next; it != this; it=it->next ) {
                                assert( it->prev == this || it->totalCost >= it->prev->totalCost );
                                assert( it->totalCost <= it->next->totalCost );
                        }
                }
                #endif
                #endif

          private:
                PathNode();
                ~PathNode();
                PathNode( const PathNode& );
                void operator=( const PathNode& );
        };


        /**
                Create a MicroPather object to solve for a best path. Detailed usage notes are
                on the main page.
        */
        class MicroPather
        {
                friend class micropather::PathNode;

          public:
                enum
                {
                        SOLVED,
                        NO_SOLUTION,
                        START_END_SAME,
                };

                /**
                        Construct the pather, passing a pointer to the object that implements
                        the Graph callbacks.

                        @param graph            The "map" that implements the Graph callbacks.
                        @param allocate         The block size that the node cache is allocated from. In some
                                                                cases setting this parameter will improve the perfomance of
                                                                the pather.
                                                                - If you have a small map, for example the size of a chessboard, set allocate
                                                                  to be the number of states+1. 65 for a chessboard. This will allow
                                                                  MicroPather to used a fixed amount of memory.
                                                                - If your map is large, something like 1/4 the number of possible
                                                                  states is good. For example, Lilith3D normally has about 16,000 
                                                                  states, so 'allocate' should be about 4000.
                */
                MicroPather( Graph* graph, unsigned allocate = 250 );
                ~MicroPather();

                /**
                        Solve for the path from start to end.

                        @param startState       Input, the starting state for the path.
                        @param endState         Input, the ending state for the path.
                        @param path                     Output, a vector of states that define the path. Empty if not found.
                        @param totalCost        Output, the cost of the path, if found.
                        @return                         Success or failure, expressed as SOLVED, NO_SOLUTION, or START_END_SAME.
                */
                int Solve( void* startState, void* endState, std::vector< void* >* path, float* totalCost );

                /// Should be called whenever the cost between states or the connection between states changes.
                void Reset();

                /*  Deprecated. Too complex for the practical value.
                        @warning It is very easy to "miss" a state that needs to be changed and break the pather.

                        As described on the main page, it is possible to change the costs (but not the connections)
                        of states without calling Reset(). Be sure that all effected states are passed to
                        StateCostChange.
                */
                //void StateCostChange( void* state );

                /**
                        Return the "checksum" of the last path returned by Solve(). Useful for debugging,
                        and a quick way to see if 2 paths are the same.
                */
                UPTR Checksum() { return checksum; }
                
                void DumpHashTable();
                
                // Debugging function to return all states that were used
                // by the last "solve" 
                void StatesInPool( std::vector< void* >* stateVec );

          private:
                MicroPather( const MicroPather& );      // undefined and unsupported
                void operator=( const MicroPather ); // undefined and unsupported
                
                void GoalReached( PathNode* node, void* start, void* end, std::vector< void* > *path );
                void RecPathNodeWalk( PathNode* node, int* count );
                
                // Allocates and returns memory for a new, unititialized node.
                PathNode* AllocatePathNode();

                // Returns a path node that is ready to go. 
                // Strictly speaking, the name is somewhat misleading, as it
                // may be reused from the cache, but it will be ready for use regardless.
                PathNode* NewPathNode( void* state, float costFromStart, float estToEnd, PathNode* parent );

                // Finds the node for state, or returns null. 
                // A node that doesn't have a correct "frame" will never be found.
                PathNode* FindPathNode( void* state, bool findStale = false ); 

                NodeCost* GetNodeNeighbors( PathNode* node, std::vector< StateCost >* neighbor, std::vector< NodeCost >* neighborNode );

                #ifdef DEBUG
                void DumpStats();
                #endif

                enum {
                        #ifdef DEBUG_PATH
                        HASH_SIZE = 16,         // In debug mode, stress the allocators more than in release.
                                                                        // The HASH_SIZE must be a power of 2.
                        #else
                        HASH_SIZE = 256,
                        #endif
                };

        unsigned Hash( void* voidval ) {
                        UPTR val = (UPTR)voidval;
            return (unsigned)((HASH_SIZE-1) & ( val + (val>>8) + (val>>16) + (val>>24) ));
        }    
    
                const unsigned ALLOCATE;                        // how big a block of pathnodes to allocate at once
                const unsigned BLOCKSIZE;                       // how many useable pathnodes are in a block

                Graph* graph;
                PathNode* hashTable[HASH_SIZE];         // a fixed hashtable used to "jumpstart" a binary search
                PathNode* pathNodeMem;                          // pointer to root of PathNode blocks
                unsigned availMem;                                      // # PathNodes available in the current block
                unsigned pathNodeCount;                         // the # of PathNodes in use
                unsigned frame;                                         // incremented with every solve, used to determine
                                                                                        // if cached data needs to be refreshed
                UPTR checksum;                                  // the checksum of the last successful "Solve".

                std::vector< StateCost > neighborVec;   // really local vars to Solve, but put here to reduce memory allocation
                std::vector< NodeCost > neighborNodeVec; // really local vars to Solve, but put here to reduce memory allocation
        };

        inline PathNode* MicroPather::FindPathNode( void* state, bool findStale )
        {
                unsigned key = Hash( state );

                PathNode* root = hashTable[key];
                #ifdef USE_BINARY_HASH
                while ( root ) {
                        if ( root->state == state ) {
                                if ( findStale || root->frame == frame )
                                        return root;
                                else
                                        return 0;
                        }
                        else if ( state > root->state ) {
                                root = root->right;
                        }
                        else {
                                assert( state < root->state );
                                root = root->left;
                        }
                }
                #else
                while( root ) {
                        if ( root->state == state ) {
                                if ( findStale || root->frame == frame )
                                        return root;
                                else
                                        return 0;
                        }
                        else {
                                root = root->left;
                        }
                }
                #endif
                return 0;
        }               
};      // namespace grinliz

#endif

Revision:	1.1
Committed:	Thu May 24 00:24:11 2007 UTC (17 years ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rel-2_1
Log Message:	I like micropather so much without ever having used it that I included it. This is not to be used directly, it should be integrated into the map management code.
#	Content
1	/*
2	Copyright (c) 2000-2003 Lee Thomason (www.grinninglizard.com)
3	Grinning Lizard Utilities.
4
5	This software is provided 'as-is', without any express or implied
6	warranty. In no event will the authors be held liable for any
7	damages arising from the use of this software.
8
9	Permission is granted to anyone to use this software for any
10	purpose, including commercial applications, and to alter it and
11	redistribute it freely, subject to the following restrictions:
12
13	1. The origin of this software must not be misrepresented; you must
14	not claim that you wrote the original software. If you use this
15	software in a product, an acknowledgment in the product documentation
16	would be appreciated but is not required.
17
18	2. Altered source versions must be plainly marked as such, and
19	must not be misrepresented as being the original software.
20
21	3. This notice may not be removed or altered from any source
22	distribution.
23	*/
24
25
26	#ifndef GRINNINGLIZARD_MICROPATHER_INCLUDED
27	#define GRINNINGLIZARD_MICROPATHER_INCLUDED
28
29	/** @mainpage MicroPather
30
31	MicroPather is a path finder and A* solver (astar or a-star) written in platform independent
32	C++ that can be easily integrated into existing code. MicroPather focuses on being a path
33	finding engine for video games but is a generic A* solver. MicroPather is open source, with
34	a license suitable for open source or commercial use.
35
36	An overview of using MicroPather is in the <A HREF="../readme.htm">readme</A> or
37	on the Grinning Lizard website: http://grinninglizard.com/micropather/
38	*/
39
40	#include <vector>
41	#include <list>
42	#include <assert.h>
43	#include <float.h>
44
45	#ifdef _DEBUG
46	#ifndef DEBUG
47	#define DEBUG
48	#endif
49	#endif
50
51	#ifndef GRINLIZ_TYPES_INCLUDED
52	#if defined(_MSC_VER) && (_MSC_VER >= 1400 )
53	#include <stdlib.h>
54	typedef uintptr_t UPTR;
55	#elif defined (__GNUC__) && (__GNUC__ >= 3 )
56	#include <stdlib.h>
57	typedef uintptr_t UPTR;
58	#else
59	// Assume not 64 bit pointers. Get a new compiler.
60	typedef unsigned UPTR;
61	#endif
62	#endif
63
64	/* USE_LIST and USE_BINARY_HASH change the some of details the pather algorithms. They
65	are set optimally in my experiments, but different applications may benefit
66	from a different combination of these #defines.
67	*/
68	#define USE_LIST
69	//#define USE_BINARY_HASH
70
71	namespace micropather
72	{
73	const float FLT_BIG = FLT_MAX / 2.0f;
74
75	/**
76	Used to pass the cost of states from the cliet application to MicroPather. This
77	structure is copied in a vector.
78
79	@sa AdjacentCost
80	*/
81	struct StateCost
82	{
83	void* state; ///< The state as a void*
84	float cost; ///< The cost to the state. Use FLT_MAX for infinite cost.
85	};
86
87
88	/**
89	A pure abstract class used to define a set of callbacks.
90	The client application inherits from
91	this class, and the methods will be called when MicroPather::Solve() is invoked.
92
93	The notion of a "state" is very important. It must have the following properties:
94	- Unique
95	- Unchanging (unless MicroPather::Reset() is called)
96
97	If the client application represents states as objects, then the state is usually
98	just the object cast to a void*. If the client application sees states as numerical
99	values, (x,y) for example, then state is an encoding of these values. MicroPather
100	never interprets or modifies the value of state.
101	*/
102	class Graph
103	{
104	public:
105	virtual ~Graph() {}
106
107	/**
108	Return the least possible cost between 2 states. For example, if your pathfinding
109	is based on distance, this is simply the straight distance between 2 points on the
110	map. If you pathfinding is based on minimum time, it is the minimal travel time
111	between 2 points given the best possible terrain.
112	*/
113	virtual float LeastCostEstimate( void* stateStart, void* stateEnd ) = 0;
114
115	/**
116	Return the exact cost from the given state to all its neighboring states. This
117	may be called multiple times, or cached by the solver. It must return the same
118	exact values for every call to MicroPather::Solve(). It should generally be a simple,
119	fast function with no callbacks into the pather.
120	*/
121	virtual void AdjacentCost( void* state, std::vector< micropather::StateCost > *adjacent ) = 0;
122
123	/**
124	This function is only used in DEBUG mode - it dumps output to stdout. Since void*
125	aren't really human readable, normally you print out some concise info (like "(1,2)")
126	without an ending newline.
127
128	@note If you are using other grinning lizard utilities, you should use GLOUTPUT for output.
129	*/
130	virtual void PrintStateInfo( void* state ) = 0;
131	};
132
133
134	class PathNode;
135
136	struct NodeCost
137	{
138	PathNode* node;
139	float cost;
140	};
141
142
143	class PathNode
144	{
145	friend class none; // Trashy trick to get rid of compiler warning, because
146	// this class has a private constructor and destructor -
147	// it can never be "new" or created on the stack, only
148	// by special allocators.
149	public:
150	void Init( unsigned _frame,
151	void* _state,
152	float _costFromStart,
153	float _estToGoal,
154	PathNode* _parent )
155	{
156	state = _state;
157	costFromStart = _costFromStart;
158	estToGoal = _estToGoal;
159	totalCost = _costFromStart + _estToGoal;
160	parent = _parent;
161	frame = _frame;
162	numAdjacent = -1;
163	left = 0;
164	#ifdef USE_BINARY_HASH
165	right = 0;
166	#endif
167	#ifdef USE_LIST
168	next = 0;
169	prev = 0;
170	#endif
171	inOpen = 0;
172	inClosed = 0;
173	}
174
175	void Reuse( unsigned _frame, float _costFromStart, float _estToGoal, PathNode* _parent )
176	{
177	costFromStart = _costFromStart;
178	estToGoal = _estToGoal;
179	parent = _parent;
180	frame = _frame;
181
182	inOpen = 0;
183	inClosed = 0;
184	}
185
186	void *state; // the client state
187	float costFromStart; // exact
188	float estToGoal; // estimated
189	float totalCost; // could be a function, but save some math.
190	PathNode* parent; // the parent is used to reconstruct the path
191	unsigned frame; // unique id for this path, so the solver can distinguish
192	// correct from stale values
193
194	enum {
195	/*
196	@enum MAX_CACHE. If you want to optimize "down deep" this is the way
197	to go. MAX_CACHE determines the number of adjacent nodes cached by
198	MicroPather. If your nodes generally have 8 or 3 neighbors (common cases)
199	changing this may increase performance, sometimes dramatically.
200	*/
201	MAX_CACHE = 4
202	};
203	// If there are 4 or less adjacent states, they will be cached as nodes.
204	NodeCost adjacent[ MAX_CACHE ];
205	int numAdjacent; // -1 is unknown & needs to be queried
206	// 0-4 adjacent is known & in 'adjacent'
207	// 5+ known, but has to be queried from Graph
208
209	PathNode* left; // Binary tree, where the 'state' is what is being compared.
210	// Also used as a "next" pointer for memory layout.
211	#ifdef USE_BINARY_HASH
212	PathNode* right;
213	#endif
214	#ifdef USE_LIST
215	PathNode next, prev;
216	#endif
217
218	unsigned inOpen:1;
219	unsigned inClosed:1;
220
221	#ifdef USE_LIST
222	void Unlink() {
223	next->prev = prev;
224	prev->next = next;
225	next = prev = 0;
226	}
227	void AddBefore( PathNode* addThis ) {
228	addThis->next = this;
229	addThis->prev = prev;
230	prev->next = addThis;
231	prev = addThis;
232	}
233	#ifdef DEBUG
234	void CheckList()
235	{
236	assert( totalCost == FLT_MAX );
237	for( PathNode* it = next; it != this; it=it->next ) {
238	assert( it->prev == this \|\| it->totalCost >= it->prev->totalCost );
239	assert( it->totalCost <= it->next->totalCost );
240	}
241	}
242	#endif
243	#endif
244
245	private:
246	PathNode();
247	~PathNode();
248	PathNode( const PathNode& );
249	void operator=( const PathNode& );
250	};
251
252
253	/**
254	Create a MicroPather object to solve for a best path. Detailed usage notes are
255	on the main page.
256	*/
257	class MicroPather
258	{
259	friend class micropather::PathNode;
260
261	public:
262	enum
263	{
264	SOLVED,
265	NO_SOLUTION,
266	START_END_SAME,
267	};
268
269	/**
270	Construct the pather, passing a pointer to the object that implements
271	the Graph callbacks.
272
273	@param graph The "map" that implements the Graph callbacks.
274	@param allocate The block size that the node cache is allocated from. In some
275	cases setting this parameter will improve the perfomance of
276	the pather.
277	- If you have a small map, for example the size of a chessboard, set allocate
278	to be the number of states+1. 65 for a chessboard. This will allow
279	MicroPather to used a fixed amount of memory.
280	- If your map is large, something like 1/4 the number of possible
281	states is good. For example, Lilith3D normally has about 16,000
282	states, so 'allocate' should be about 4000.
283	*/
284	MicroPather( Graph* graph, unsigned allocate = 250 );
285	~MicroPather();
286
287	/**
288	Solve for the path from start to end.
289
290	@param startState Input, the starting state for the path.
291	@param endState Input, the ending state for the path.
292	@param path Output, a vector of states that define the path. Empty if not found.
293	@param totalCost Output, the cost of the path, if found.
294	@return Success or failure, expressed as SOLVED, NO_SOLUTION, or START_END_SAME.
295	*/
296	int Solve( void* startState, void* endState, std::vector< void* >* path, float* totalCost );
297
298	/// Should be called whenever the cost between states or the connection between states changes.
299	void Reset();
300
301	/* Deprecated. Too complex for the practical value.
302	@warning It is very easy to "miss" a state that needs to be changed and break the pather.
303
304	As described on the main page, it is possible to change the costs (but not the connections)
305	of states without calling Reset(). Be sure that all effected states are passed to
306	StateCostChange.
307	*/
308	//void StateCostChange( void* state );
309
310	/**
311	Return the "checksum" of the last path returned by Solve(). Useful for debugging,
312	and a quick way to see if 2 paths are the same.
313	*/
314	UPTR Checksum() { return checksum; }
315
316	void DumpHashTable();
317
318	// Debugging function to return all states that were used
319	// by the last "solve"
320	void StatesInPool( std::vector< void* >* stateVec );
321
322	private:
323	MicroPather( const MicroPather& ); // undefined and unsupported
324	void operator=( const MicroPather ); // undefined and unsupported
325
326	void GoalReached( PathNode* node, void* start, void* end, std::vector< void* > *path );
327	void RecPathNodeWalk( PathNode* node, int* count );
328
329	// Allocates and returns memory for a new, unititialized node.
330	PathNode* AllocatePathNode();
331
332	// Returns a path node that is ready to go.
333	// Strictly speaking, the name is somewhat misleading, as it
334	// may be reused from the cache, but it will be ready for use regardless.
335	PathNode* NewPathNode( void* state, float costFromStart, float estToEnd, PathNode* parent );
336
337	// Finds the node for state, or returns null.
338	// A node that doesn't have a correct "frame" will never be found.
339	PathNode* FindPathNode( void* state, bool findStale = false );
340
341	NodeCost* GetNodeNeighbors( PathNode* node, std::vector< StateCost >* neighbor, std::vector< NodeCost >* neighborNode );
342
343	#ifdef DEBUG
344	void DumpStats();
345	#endif
346
347	enum {
348	#ifdef DEBUG_PATH
349	HASH_SIZE = 16, // In debug mode, stress the allocators more than in release.
350	// The HASH_SIZE must be a power of 2.
351	#else
352	HASH_SIZE = 256,
353	#endif
354	};
355
356	unsigned Hash( void* voidval ) {
357	UPTR val = (UPTR)voidval;
358	return (unsigned)((HASH_SIZE-1) & ( val + (val>>8) + (val>>16) + (val>>24) ));
359	}
360
361	const unsigned ALLOCATE; // how big a block of pathnodes to allocate at once
362	const unsigned BLOCKSIZE; // how many useable pathnodes are in a block
363
364	Graph* graph;
365	PathNode* hashTable[HASH_SIZE]; // a fixed hashtable used to "jumpstart" a binary search
366	PathNode* pathNodeMem; // pointer to root of PathNode blocks
367	unsigned availMem; // # PathNodes available in the current block
368	unsigned pathNodeCount; // the # of PathNodes in use
369	unsigned frame; // incremented with every solve, used to determine
370	// if cached data needs to be refreshed
371	UPTR checksum; // the checksum of the last successful "Solve".
372
373	std::vector< StateCost > neighborVec; // really local vars to Solve, but put here to reduce memory allocation
374	std::vector< NodeCost > neighborNodeVec; // really local vars to Solve, but put here to reduce memory allocation
375	};
376
377	inline PathNode* MicroPather::FindPathNode( void* state, bool findStale )
378	{
379	unsigned key = Hash( state );
380
381	PathNode* root = hashTable[key];
382	#ifdef USE_BINARY_HASH
383	while ( root ) {
384	if ( root->state == state ) {
385	if ( findStale \|\| root->frame == frame )
386	return root;
387	else
388	return 0;
389	}
390	else if ( state > root->state ) {
391	root = root->right;
392	}
393	else {
394	assert( state < root->state );
395	root = root->left;
396	}
397	}
398	#else
399	while( root ) {
400	if ( root->state == state ) {
401	if ( findStale \|\| root->frame == frame )
402	return root;
403	else
404	return 0;
405	}
406	else {
407	root = root->left;
408	}
409	}
410	#endif
411	return 0;
412	}
413	}; // namespace grinliz
414
415	#endif
416