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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;
unsigned int heapsize;
unsigned 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, unsigned 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) {
unsigned 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) {
unsigned 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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