mutter/cogl/cogl-path/tesselator/priorityq-heap.c
2016-04-22 16:44:31 +02:00

257 lines
6.4 KiB
C

/*
* SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
* Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice including the dates of first publication and
* either this permission notice or a reference to
* http://oss.sgi.com/projects/FreeB/
* shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
* OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* Except as contained in this notice, the name of Silicon Graphics, Inc.
* shall not be used in advertising or otherwise to promote the sale, use or
* other dealings in this Software without prior written authorization from
* Silicon Graphics, Inc.
*/
/*
** Author: Eric Veach, July 1994.
**
*/
#include <stddef.h>
#include <assert.h>
#include "priorityq-heap.h"
#include "memalloc.h"
#define INIT_SIZE 32
#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif
#ifdef FOR_TRITE_TEST_PROGRAM
#define LEQ(x,y) (*pq->leq)(x,y)
#else
/* Violates modularity, but a little faster */
#include "geom.h"
#define LEQ(x,y) VertLeq((GLUvertex *)x, (GLUvertex *)y)
#endif
/* really __gl_pqHeapNewPriorityQ */
PriorityQ *pqNewPriorityQ( int (*leq)(PQkey key1, PQkey key2) )
{
PriorityQ *pq = (PriorityQ *)memAlloc( sizeof( PriorityQ ));
if (pq == NULL) return NULL;
pq->size = 0;
pq->max = INIT_SIZE;
pq->nodes = (PQnode *)memAlloc( (INIT_SIZE + 1) * sizeof(pq->nodes[0]) );
if (pq->nodes == NULL) {
memFree(pq);
return NULL;
}
pq->handles = (PQhandleElem *)memAlloc( (INIT_SIZE + 1) * sizeof(pq->handles[0]) );
if (pq->handles == NULL) {
memFree(pq->nodes);
memFree(pq);
return NULL;
}
pq->initialized = FALSE;
pq->freeList = 0;
pq->leq = leq;
pq->nodes[1].handle = 1; /* so that Minimum() returns NULL */
pq->handles[1].key = NULL;
return pq;
}
/* really __gl_pqHeapDeletePriorityQ */
void pqDeletePriorityQ( PriorityQ *pq )
{
memFree( pq->handles );
memFree( pq->nodes );
memFree( pq );
}
static void FloatDown( PriorityQ *pq, long curr )
{
PQnode *n = pq->nodes;
PQhandleElem *h = pq->handles;
PQhandle hCurr, hChild;
long child;
hCurr = n[curr].handle;
for( ;; ) {
child = curr << 1;
if( child < pq->size && LEQ( h[n[child+1].handle].key,
h[n[child].handle].key )) {
++child;
}
assert(child <= pq->max);
hChild = n[child].handle;
if( child > pq->size || LEQ( h[hCurr].key, h[hChild].key )) {
n[curr].handle = hCurr;
h[hCurr].node = curr;
break;
}
n[curr].handle = hChild;
h[hChild].node = curr;
curr = child;
}
}
static void FloatUp( PriorityQ *pq, long curr )
{
PQnode *n = pq->nodes;
PQhandleElem *h = pq->handles;
PQhandle hCurr, hParent;
long parent;
hCurr = n[curr].handle;
for( ;; ) {
parent = curr >> 1;
hParent = n[parent].handle;
if( parent == 0 || LEQ( h[hParent].key, h[hCurr].key )) {
n[curr].handle = hCurr;
h[hCurr].node = curr;
break;
}
n[curr].handle = hParent;
h[hParent].node = curr;
curr = parent;
}
}
/* really __gl_pqHeapInit */
void pqInit( PriorityQ *pq )
{
long i;
/* This method of building a heap is O(n), rather than O(n lg n). */
for( i = pq->size; i >= 1; --i ) {
FloatDown( pq, i );
}
pq->initialized = TRUE;
}
/* really __gl_pqHeapInsert */
/* returns LONG_MAX iff out of memory */
PQhandle pqInsert( PriorityQ *pq, PQkey keyNew )
{
long curr;
PQhandle free_handle;
curr = ++ pq->size;
if( (curr*2) > pq->max ) {
PQnode *saveNodes= pq->nodes;
PQhandleElem *saveHandles= pq->handles;
/* If the heap overflows, double its size. */
pq->max <<= 1;
pq->nodes = (PQnode *)memRealloc( pq->nodes,
(size_t)
((pq->max + 1) * sizeof( pq->nodes[0] )));
if (pq->nodes == NULL) {
pq->nodes = saveNodes; /* restore ptr to free upon return */
return LONG_MAX;
}
pq->handles = (PQhandleElem *)memRealloc( pq->handles,
(size_t)
((pq->max + 1) *
sizeof( pq->handles[0] )));
if (pq->handles == NULL) {
pq->handles = saveHandles; /* restore ptr to free upon return */
return LONG_MAX;
}
}
if( pq->freeList == 0 ) {
free_handle = curr;
} else {
free_handle = pq->freeList;
pq->freeList = pq->handles[free_handle].node;
}
pq->nodes[curr].handle = free_handle;
pq->handles[free_handle].node = curr;
pq->handles[free_handle].key = keyNew;
if( pq->initialized ) {
FloatUp( pq, curr );
}
assert(free_handle != LONG_MAX);
return free_handle;
}
/* really __gl_pqHeapExtractMin */
PQkey pqExtractMin( PriorityQ *pq )
{
PQnode *n = pq->nodes;
PQhandleElem *h = pq->handles;
PQhandle hMin = n[1].handle;
PQkey min = h[hMin].key;
if( pq->size > 0 ) {
n[1].handle = n[pq->size].handle;
h[n[1].handle].node = 1;
h[hMin].key = NULL;
h[hMin].node = pq->freeList;
pq->freeList = hMin;
if( -- pq->size > 0 ) {
FloatDown( pq, 1 );
}
}
return min;
}
/* really __gl_pqHeapDelete */
void pqDelete( PriorityQ *pq, PQhandle hCurr )
{
PQnode *n = pq->nodes;
PQhandleElem *h = pq->handles;
long curr;
assert( hCurr >= 1 && hCurr <= pq->max && h[hCurr].key != NULL );
curr = h[hCurr].node;
n[curr].handle = n[pq->size].handle;
h[n[curr].handle].node = curr;
if( curr <= -- pq->size ) {
if( curr <= 1 || LEQ( h[n[curr>>1].handle].key, h[n[curr].handle].key )) {
FloatDown( pq, curr );
} else {
FloatUp( pq, curr );
}
}
h[hCurr].key = NULL;
h[hCurr].node = pq->freeList;
pq->freeList = hCurr;
}