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/*
* The Python Imaging Library
* $Id$
*
* heap data type used by the image quantizer
*
* history:
* 98-09-10 tjs Contributed
* 98-12-29 fl Added to PIL 1.0b1
*
* Written by Toby J Sargeant <tjs@longford.cs.monash.edu.au>.
*
* Copyright (c) 1998 by Toby J Sargeant
* Copyright (c) 1998 by Secret Labs AB
*
* See the README file for information on usage and redistribution.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include "QuantHeap.h"
struct _Heap {
void **heap;
int heapsize;
int heapcount;
HeapCmpFunc cf;
};
#define INITIAL_SIZE 256
// #define DEBUG
#ifdef DEBUG
static int _heap_test(Heap *);
#endif
void ImagingQuantHeapFree(Heap *h) {
free(h->heap);
free(h);
}
static int _heap_grow(Heap *h,int newsize) {
void *newheap;
if (!newsize) newsize=h->heapsize<<1;
if (newsize<h->heapsize) return 0;
if (newsize > INT_MAX / sizeof(void *)){
return 0;
}
/* malloc check ok, using calloc for overflow, also checking
above due to memcpy below*/
newheap=calloc(newsize, sizeof(void *));
if (!newheap) return 0;
memcpy(newheap,h->heap,sizeof(void *)*h->heapsize);
free(h->heap);
h->heap=newheap;
h->heapsize=newsize;
return 1;
}
#ifdef DEBUG
static int _heap_test(Heap *h) {
int k;
for (k=1;k*2<=h->heapcount;k++) {
if (h->cf(h,h->heap[k],h->heap[k*2])<0) {
printf ("heap is bad\n");
return 0;
}
if (k*2+1<=h->heapcount && h->cf(h,h->heap[k],h->heap[k*2+1])<0) {
printf ("heap is bad\n");
return 0;
}
}
return 1;
}
#endif
int ImagingQuantHeapRemove(Heap* h,void **r) {
int k,l;
void *v;
if (!h->heapcount) {
return 0;
}
*r=h->heap[1];
v=h->heap[h->heapcount--];
for (k=1;k*2<=h->heapcount;k=l) {
l=k*2;
if (l<h->heapcount) {
if (h->cf(h,h->heap[l],h->heap[l+1])<0) {
l++;
}
}
if (h->cf(h,v,h->heap[l])>0) {
break;
}
h->heap[k]=h->heap[l];
}
h->heap[k]=v;
#ifdef DEBUG
if (!_heap_test(h)) { printf ("oops - heap_remove messed up the heap\n"); exit(1); }
#endif
return 1;
}
int ImagingQuantHeapAdd(Heap *h,void *val) {
int k;
if (h->heapcount==h->heapsize-1) {
_heap_grow(h,0);
}
k=++h->heapcount;
while (k!=1) {
if (h->cf(h,val,h->heap[k/2])<=0) {
break;
}
h->heap[k]=h->heap[k/2];
k>>=1;
}
h->heap[k]=val;
#ifdef DEBUG
if (!_heap_test(h)) { printf ("oops - heap_add messed up the heap\n"); exit(1); }
#endif
return 1;
}
int ImagingQuantHeapTop(Heap *h,void **r) {
if (!h->heapcount) {
return 0;
}
*r=h->heap[1];
return 1;
}
Heap *ImagingQuantHeapNew(HeapCmpFunc cf) {
Heap *h;
/* malloc check ok, small constant allocation */
h=malloc(sizeof(Heap));
if (!h) return NULL;
h->heapsize=INITIAL_SIZE;
/* malloc check ok, using calloc for overflow */
h->heap=calloc(h->heapsize, sizeof(void *));
if (!h->heap) {
free(h);
return NULL;
}
h->heapcount=0;
h->cf=cf;
return h;
}
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