SGI SI GLU library

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+/*
+** License Applicability. Except to the extent portions of this file are
+** made subject to an alternative license as permitted in the SGI Free
+** Software License B, Version 1.1 (the "License"), the contents of this
+** file are subject only to the provisions of the License. You may not use
+** this file except in compliance with the License. You may obtain a copy
+** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
+** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
+** 
+** http://oss.sgi.com/projects/FreeB
+** 
+** Note that, as provided in the License, the Software is distributed on an
+** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
+** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
+** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
+** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
+** 
+** Original Code. The Original Code is: OpenGL Sample Implementation,
+** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
+** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
+** Copyright in any portions created by third parties is as indicated
+** elsewhere herein. All Rights Reserved.
+** 
+** Additional Notice Provisions: The application programming interfaces
+** established by SGI in conjunction with the Original Code are The
+** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
+** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
+** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
+** Window System(R) (Version 1.3), released October 19, 1998. This software
+** was created using the OpenGL(R) version 1.2.1 Sample Implementation
+** published by SGI, but has not been independently verified as being
+** compliant with the OpenGL(R) version 1.2.1 Specification.
+**
+*/
+/*
+** Author: Eric Veach, July 1994.
+**
+** $Date: 2001/03/17 00:25:41 $ $Revision: 1.1 $
+** $Header: /home/krh/git/sync/mesa-cvs-repo/Mesa/src/glu/sgi/libtess/priorityq-heap.h,v 1.1 2001/03/17 00:25:41 brianp Exp $
+*/
+
+#ifndef __priorityq_heap_h_
+#define __priorityq_heap_h_
+
+/* Use #define's so that another heap implementation can use this one */
+
+#define PQkey			PQHeapKey
+#define PQhandle		PQHeapHandle
+#define PriorityQ		PriorityQHeap
+
+#define pqNewPriorityQ(leq)	__gl_pqHeapNewPriorityQ(leq)
+#define pqDeletePriorityQ(pq)	__gl_pqHeapDeletePriorityQ(pq)
+
+/* The basic operations are insertion of a new key (pqInsert),
+ * and examination/extraction of a key whose value is minimum
+ * (pqMinimum/pqExtractMin).  Deletion is also allowed (pqDelete);
+ * for this purpose pqInsert returns a "handle" which is supplied
+ * as the argument.
+ *
+ * An initial heap may be created efficiently by calling pqInsert
+ * repeatedly, then calling pqInit.  In any case pqInit must be called
+ * before any operations other than pqInsert are used.
+ *
+ * If the heap is empty, pqMinimum/pqExtractMin will return a NULL key.
+ * This may also be tested with pqIsEmpty.
+ */
+#define pqInit(pq)		__gl_pqHeapInit(pq)
+#define pqInsert(pq,key)	__gl_pqHeapInsert(pq,key)
+#define pqMinimum(pq)		__gl_pqHeapMinimum(pq)
+#define pqExtractMin(pq)	__gl_pqHeapExtractMin(pq)
+#define pqDelete(pq,handle)	__gl_pqHeapDelete(pq,handle)
+#define pqIsEmpty(pq)		__gl_pqHeapIsEmpty(pq)
+
+
+/* Since we support deletion the data structure is a little more
+ * complicated than an ordinary heap.  "nodes" is the heap itself;
+ * active nodes are stored in the range 1..pq->size.  When the
+ * heap exceeds its allocated size (pq->max), its size doubles.
+ * The children of node i are nodes 2i and 2i+1.
+ *
+ * Each node stores an index into an array "handles".  Each handle
+ * stores a key, plus a pointer back to the node which currently
+ * represents that key (ie. nodes[handles[i].node].handle == i).
+ */
+
+typedef void *PQkey;
+typedef long PQhandle;
+typedef struct PriorityQ PriorityQ;
+
+typedef struct { PQhandle handle; } PQnode;
+typedef struct { PQkey key; PQhandle node; } PQhandleElem;
+
+struct PriorityQ {
+  PQnode	*nodes;
+  PQhandleElem	*handles;
+  long		size, max;
+  PQhandle	freeList;
+  int		initialized;
+  int		(*leq)(PQkey key1, PQkey key2);
+};
+  
+PriorityQ	*pqNewPriorityQ( int (*leq)(PQkey key1, PQkey key2) );
+void		pqDeletePriorityQ( PriorityQ *pq );
+
+void		pqInit( PriorityQ *pq );
+PQhandle	pqInsert( PriorityQ *pq, PQkey key );
+PQkey		pqExtractMin( PriorityQ *pq );
+void		pqDelete( PriorityQ *pq, PQhandle handle );
+
+
+#define __gl_pqHeapMinimum(pq)	((pq)->handles[(pq)->nodes[1].handle].key)
+#define __gl_pqHeapIsEmpty(pq)	((pq)->size == 0)
+
+#endif