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31 ** Author: Eric Veach, July 1994.
37 #include "priorityq-heap.h"
49 #ifdef FOR_TRITE_TEST_PROGRAM
50 #define LEQ(x,y) (*pq->leq)(x,y)
52 /* Violates modularity, but a little faster */
54 #define LEQ(x,y) VertLeq((GLUvertex *)x, (GLUvertex *)y)
57 /* really __gl_pqHeapNewPriorityQ */
58 PriorityQ *pqNewPriorityQ( int (*leq)(PQkey key1, PQkey key2) )
60 PriorityQ *pq = (PriorityQ *)memAlloc( sizeof( PriorityQ ));
61 if (pq == NULL) return NULL;
65 pq->nodes = (PQnode *)memAlloc( (INIT_SIZE + 1) * sizeof(pq->nodes[0]) );
66 if (pq->nodes == NULL) {
71 pq->handles = (PQhandleElem *)memAlloc( (INIT_SIZE + 1) * sizeof(pq->handles[0]) );
72 if (pq->handles == NULL) {
78 pq->initialized = FALSE;
82 pq->nodes[1].handle = 1; /* so that Minimum() returns NULL */
83 pq->handles[1].key = NULL;
87 /* really __gl_pqHeapDeletePriorityQ */
88 void pqDeletePriorityQ( PriorityQ *pq )
90 memFree( pq->handles );
96 static void FloatDown( PriorityQ *pq, long curr )
98 PQnode *n = pq->nodes;
99 PQhandleElem *h = pq->handles;
100 PQhandle hCurr, hChild;
103 hCurr = n[curr].handle;
106 if( child < pq->size && LEQ( h[n[child+1].handle].key,
107 h[n[child].handle].key )) {
111 assert(child <= pq->max);
113 hChild = n[child].handle;
114 if( child > pq->size || LEQ( h[hCurr].key, h[hChild].key )) {
115 n[curr].handle = hCurr;
116 h[hCurr].node = curr;
119 n[curr].handle = hChild;
120 h[hChild].node = curr;
126 static void FloatUp( PriorityQ *pq, long curr )
128 PQnode *n = pq->nodes;
129 PQhandleElem *h = pq->handles;
130 PQhandle hCurr, hParent;
133 hCurr = n[curr].handle;
136 hParent = n[parent].handle;
137 if( parent == 0 || LEQ( h[hParent].key, h[hCurr].key )) {
138 n[curr].handle = hCurr;
139 h[hCurr].node = curr;
142 n[curr].handle = hParent;
143 h[hParent].node = curr;
148 /* really __gl_pqHeapInit */
149 void pqInit( PriorityQ *pq )
153 /* This method of building a heap is O(n), rather than O(n lg n). */
155 for( i = pq->size; i >= 1; --i ) {
158 pq->initialized = TRUE;
161 /* really __gl_pqHeapInsert */
162 /* returns LONG_MAX iff out of memory */
163 PQhandle pqInsert( PriorityQ *pq, PQkey keyNew )
166 PQhandle free_handle;
169 if( (curr*2) > pq->max ) {
170 PQnode *saveNodes= pq->nodes;
171 PQhandleElem *saveHandles= pq->handles;
173 /* If the heap overflows, double its size. */
175 pq->nodes = (PQnode *)memRealloc( pq->nodes,
177 ((pq->max + 1) * sizeof( pq->nodes[0] )));
178 if (pq->nodes == NULL) {
179 pq->nodes = saveNodes; /* restore ptr to free upon return */
182 pq->handles = (PQhandleElem *)memRealloc( pq->handles,
185 sizeof( pq->handles[0] )));
186 if (pq->handles == NULL) {
187 pq->handles = saveHandles; /* restore ptr to free upon return */
192 if( pq->freeList == 0 ) {
195 free_handle = pq->freeList;
196 pq->freeList = pq->handles[free_handle].node;
199 pq->nodes[curr].handle = free_handle;
200 pq->handles[free_handle].node = curr;
201 pq->handles[free_handle].key = keyNew;
203 if( pq->initialized ) {
206 assert(free_handle != LONG_MAX);
210 /* really __gl_pqHeapExtractMin */
211 PQkey pqExtractMin( PriorityQ *pq )
213 PQnode *n = pq->nodes;
214 PQhandleElem *h = pq->handles;
215 PQhandle hMin = n[1].handle;
216 PQkey min = h[hMin].key;
219 n[1].handle = n[pq->size].handle;
220 h[n[1].handle].node = 1;
223 h[hMin].node = pq->freeList;
226 if( -- pq->size > 0 ) {
233 /* really __gl_pqHeapDelete */
234 void pqDelete( PriorityQ *pq, PQhandle hCurr )
236 PQnode *n = pq->nodes;
237 PQhandleElem *h = pq->handles;
240 assert( hCurr >= 1 && hCurr <= pq->max && h[hCurr].key != NULL );
242 curr = h[hCurr].node;
243 n[curr].handle = n[pq->size].handle;
244 h[n[curr].handle].node = curr;
246 if( curr <= -- pq->size ) {
247 if( curr <= 1 || LEQ( h[n[curr>>1].handle].key, h[n[curr].handle].key )) {
248 FloatDown( pq, curr );
254 h[hCurr].node = pq->freeList;
255 pq->freeList = hCurr;