src/glu/sgi/libtess/priorityq.c

   1 /*
   2 ** License Applicability. Except to the extent portions of this file are
   3 ** made subject to an alternative license as permitted in the SGI Free
   4 ** Software License B, Version 1.1 (the "License"), the contents of this
   5 ** file are subject only to the provisions of the License. You may not use
   6 ** this file except in compliance with the License. You may obtain a copy
   7 ** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
   8 ** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
   9 **
  10 ** http://oss.sgi.com/projects/FreeB
  11 **
  12 ** Note that, as provided in the License, the Software is distributed on an
  13 ** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
  14 ** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
  15 ** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
  16 ** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
  17 **
  18 ** Original Code. The Original Code is: OpenGL Sample Implementation,
  19 ** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
  20 ** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
  21 ** Copyright in any portions created by third parties is as indicated
  22 ** elsewhere herein. All Rights Reserved.
  23 **
  24 ** Additional Notice Provisions: The application programming interfaces
  25 ** established by SGI in conjunction with the Original Code are The
  26 ** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
  27 ** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
  28 ** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
  29 ** Window System(R) (Version 1.3), released October 19, 1998. This software
  30 ** was created using the OpenGL(R) version 1.2.1 Sample Implementation
  31 ** published by SGI, but has not been independently verified as being
  32 ** compliant with the OpenGL(R) version 1.2.1 Specification.
  33 **
  34 */
  35 /*
  36 ** Author: Eric Veach, July 1994.
  37 **
  38 */
  39
  40 #include "gluos.h"
  41 #include <stddef.h>
  42 #include <assert.h>
  43 #include <limits.h>             /* LONG_MAX */
  44 #include "memalloc.h"
  45
  46 /* Include all the code for the regular heap-based queue here. */
  47
  48 #include "priorityq-heap.c"
  49
  50 /* Now redefine all the function names to map to their "Sort" versions. */
  51
  52 #include "priorityq-sort.h"
  53
  54 /* really __gl_pqSortNewPriorityQ */
  55 PriorityQ *pqNewPriorityQ( int (*leq)(PQkey key1, PQkey key2) )
  56 {
  57   PriorityQ *pq = (PriorityQ *)memAlloc( sizeof( PriorityQ ));
  58   if (pq == NULL) return NULL;
  59
  60   pq->heap = __gl_pqHeapNewPriorityQ( leq );
  61   if (pq->heap == NULL) {
  62      memFree(pq);
  63      return NULL;
  64   }
  65
  66   pq->keys = (PQHeapKey *)memAlloc( INIT_SIZE * sizeof(pq->keys[0]) );
  67   if (pq->keys == NULL) {
  68      __gl_pqHeapDeletePriorityQ(pq->heap);
  69      memFree(pq);
  70      return NULL;
  71   }
  72
  73   pq->size = 0;
  74   pq->max = INIT_SIZE;
  75   pq->initialized = FALSE;
  76   pq->leq = leq;
  77   return pq;
  78 }
  79
  80 /* really __gl_pqSortDeletePriorityQ */
  81 void pqDeletePriorityQ( PriorityQ *pq )
  82 {
  83   assert(pq != NULL);
  84   if (pq->heap != NULL) __gl_pqHeapDeletePriorityQ( pq->heap );
  85   if (pq->order != NULL) memFree( pq->order );
  86   if (pq->keys != NULL) memFree( pq->keys );
  87   memFree( pq );
  88 }
  89
  90
  91 #define LT(x,y)         (! LEQ(y,x))
  92 #define GT(x,y)         (! LEQ(x,y))
  93 #define Swap(a,b)       if(1){PQkey *tmp = *a; *a = *b; *b = tmp;}else
  94
  95 /* really __gl_pqSortInit */
  96 int pqInit( PriorityQ *pq )
  97 {
  98   PQkey **p, **r, **i, **j, *piv;
  99   struct { PQkey **p, **r; } Stack[50], *top = Stack;
 100   unsigned long seed = 2016473283;
 101
 102   /* Create an array of indirect pointers to the keys, so that we
 103    * the handles we have returned are still valid.
 104    */
 105 /*
 106   pq->order = (PQHeapKey **)memAlloc( (size_t)
 107                                   (pq->size * sizeof(pq->order[0])) );
 108 */
 109   pq->order = (PQHeapKey **)memAlloc( (size_t)
 110                                   ((pq->size+1) * sizeof(pq->order[0])) );
 111 /* the previous line is a patch to compensate for the fact that IBM */
 112 /* machines return a null on a malloc of zero bytes (unlike SGI),   */
 113 /* so we have to put in this defense to guard against a memory      */
 114 /* fault four lines down. from fossum@austin.ibm.com.               */
 115   if (pq->order == NULL) return 0;
 116
 117   p = pq->order;
 118   r = p + pq->size - 1;
 119   for( piv = pq->keys, i = p; i <= r; ++piv, ++i ) {
 120     *i = piv;
 121   }
 122
 123   /* Sort the indirect pointers in descending order,
 124    * using randomized Quicksort
 125    */
 126   top->p = p; top->r = r; ++top;
 127   while( --top >= Stack ) {
 128     p = top->p;
 129     r = top->r;
 130     while( r > p + 10 ) {
 131       seed = seed * 1539415821 + 1;
 132       i = p + seed % (r - p + 1);
 133       piv = *i;
 134       *i = *p;
 135       *p = piv;
 136       i = p - 1;
 137       j = r + 1;
 138       do {
 139         do { ++i; } while( GT( **i, *piv ));
 140         do { --j; } while( LT( **j, *piv ));
 141         Swap( i, j );
 142       } while( i < j );
 143       Swap( i, j );     /* Undo last swap */
 144       if( i - p < r - j ) {
 145         top->p = j+1; top->r = r; ++top;
 146         r = i-1;
 147       } else {
 148         top->p = p; top->r = i-1; ++top;
 149         p = j+1;
 150       }
 151     }
 152     /* Insertion sort small lists */
 153     for( i = p+1; i <= r; ++i ) {
 154       piv = *i;
 155       for( j = i; j > p && LT( **(j-1), *piv ); --j ) {
 156         *j = *(j-1);
 157       }
 158       *j = piv;
 159     }
 160   }
 161   pq->max = pq->size;
 162   pq->initialized = TRUE;
 163   __gl_pqHeapInit( pq->heap );  /* always succeeds */
 164
 165 #ifndef NDEBUG
 166   p = pq->order;
 167   r = p + pq->size - 1;
 168   for( i = p; i < r; ++i ) {
 169     assert( LEQ( **(i+1), **i ));
 170   }
 171 #endif
 172
 173   return 1;
 174 }
 175
 176 /* really __gl_pqSortInsert */
 177 /* returns LONG_MAX iff out of memory */
 178 PQhandle pqInsert( PriorityQ *pq, PQkey keyNew )
 179 {
 180   long curr;
 181
 182   if( pq->initialized ) {
 183     return __gl_pqHeapInsert( pq->heap, keyNew );
 184   }
 185   curr = pq->size;
 186   if( ++ pq->size >= pq->max ) {
 187     PQkey *saveKey= pq->keys;
 188
 189     /* If the heap overflows, double its size. */
 190     pq->max <<= 1;
 191     pq->keys = (PQHeapKey *)memRealloc( pq->keys,
 192                                         (size_t)
 193                                          (pq->max * sizeof( pq->keys[0] )));
 194     if (pq->keys == NULL) {
 195        pq->keys = saveKey;      /* restore ptr to free upon return */
 196        return LONG_MAX;
 197     }
 198   }
 199   assert(curr != LONG_MAX);
 200   pq->keys[curr] = keyNew;
 201
 202   /* Negative handles index the sorted array. */
 203   return -(curr+1);
 204 }
 205
 206 /* really __gl_pqSortExtractMin */
 207 PQkey pqExtractMin( PriorityQ *pq )
 208 {
 209   PQkey sortMin, heapMin;
 210
 211   if( pq->size == 0 ) {
 212     return __gl_pqHeapExtractMin( pq->heap );
 213   }
 214   sortMin = *(pq->order[pq->size-1]);
 215   if( ! __gl_pqHeapIsEmpty( pq->heap )) {
 216     heapMin = __gl_pqHeapMinimum( pq->heap );
 217     if( LEQ( heapMin, sortMin )) {
 218       return __gl_pqHeapExtractMin( pq->heap );
 219     }
 220   }
 221   do {
 222     -- pq->size;
 223   } while( pq->size > 0 && *(pq->order[pq->size-1]) == NULL );
 224   return sortMin;
 225 }
 226
 227 /* really __gl_pqSortMinimum */
 228 PQkey pqMinimum( PriorityQ *pq )
 229 {
 230   PQkey sortMin, heapMin;
 231
 232   if( pq->size == 0 ) {
 233     return __gl_pqHeapMinimum( pq->heap );
 234   }
 235   sortMin = *(pq->order[pq->size-1]);
 236   if( ! __gl_pqHeapIsEmpty( pq->heap )) {
 237     heapMin = __gl_pqHeapMinimum( pq->heap );
 238     if( LEQ( heapMin, sortMin )) {
 239       return heapMin;
 240     }
 241   }
 242   return sortMin;
 243 }
 244
 245 /* really __gl_pqSortIsEmpty */
 246 int pqIsEmpty( PriorityQ *pq )
 247 {
 248   return (pq->size == 0) && __gl_pqHeapIsEmpty( pq->heap );
 249 }
 250
 251 /* really __gl_pqSortDelete */
 252 void pqDelete( PriorityQ *pq, PQhandle curr )
 253 {
 254   if( curr >= 0 ) {
 255     __gl_pqHeapDelete( pq->heap, curr );
 256     return;
 257   }
 258   curr = -(curr+1);
 259   assert( curr < pq->max && pq->keys[curr] != NULL );
 260
 261   pq->keys[curr] = NULL;
 262   while( pq->size > 0 && *(pq->order[pq->size-1]) == NULL ) {
 263     -- pq->size;
 264   }
 265 }