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/* SPDX-License-Identifier: GPL-3.0-or-later */
#include "heap.h"
#include <stdint.h>
#include <stdlib.h>
int heap_init(heap_t* heap, size_t capacity, size_t user_sizeof) {
heap->nodes = malloc(capacity * (sizeof(heap_node_t) + user_sizeof));
if (!heap->nodes) {
return -1;
}
void* ptr = heap->nodes + capacity;
for (size_t i = 0; i < capacity; i++) {
heap->nodes[i].value = 0;
heap->nodes[i].user = ptr;
ptr += user_sizeof;
}
heap->capacity = capacity;
heap->count = 0;
return 0;
}
#define PARENT(i) (((i) - 1) / 2)
#define SWAP(a, b) do { \
heap_node_t tmp = *(a); \
*(a) = *(b); \
*(b) = tmp; \
} while (0)
heap_node_t* heap_next_insert(heap_t* heap) {
if (heap->count >= heap->capacity) {
return nullptr;
}
return &heap->nodes[heap->count];
}
void heap_insert(heap_t* heap, uint64_t value) {
if (heap->count >= heap->capacity) {
return;
}
heap->count++;
size_t i = heap->count - 1;
heap->nodes[i].value = value;
while (i != 0 && heap->nodes[PARENT(i)].value > heap->nodes[i].value) {
SWAP(&heap->nodes[i], &heap->nodes[PARENT(i)]);
i = PARENT(i);
}
}
#define LEFT(i) (2 * (i) + 1)
#define RIGHT(i) (2 * (i) + 2)
heap_node_t* heap_next_extract(heap_t* heap) {
if (heap->count == 0) {
return nullptr;
}
return &heap->nodes[0];
}
void heap_extract(heap_t* heap) {
if (heap->count <= 1) {
heap->count = 0;
return;
}
SWAP(&heap->nodes[0], &heap->nodes[heap->count - 1]);
heap->count--;
size_t i = 0;
while (true) {
size_t smallest = i;
size_t left = LEFT(i);
size_t right = RIGHT(i);
if (left < heap->count && heap->nodes[left].value < heap->nodes[smallest].value) {
smallest = left;
}
if (right < heap->count && heap->nodes[right].value < heap->nodes[smallest].value) {
smallest = right;
}
if (smallest == i) {
break;
}
SWAP(&heap->nodes[i], &heap->nodes[smallest]);
i = smallest;
}
}
void heap_free(heap_t* heap) {
free(heap->nodes);
heap->capacity = 0;
heap->count = 0;
}
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