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pheap.h
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1/*
2 * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 */
6
7#ifndef _PICO_UTIL_PHEAP_H
8#define _PICO_UTIL_PHEAP_H
9
10#include "pico.h"
11
12#ifdef __cplusplus
13extern "C" {
14#endif
15
16// PICO_CONFIG: PARAM_ASSERTIONS_ENABLED_PHEAP, Enable/disable assertions in the pheap module, type=bool, default=0, group=pico_util
17#ifndef PARAM_ASSERTIONS_ENABLED_PHEAP
18#define PARAM_ASSERTIONS_ENABLED_PHEAP 0
19#endif
20
37// PICO_CONFIG: PICO_PHEAP_MAX_ENTRIES, Maximum number of entries in the pheap, min=1, max=65534, default=255, group=pico_util
38#ifndef PICO_PHEAP_MAX_ENTRIES
39#define PICO_PHEAP_MAX_ENTRIES 255
40#endif
41
42// public heap_node ids are numbered from 1 (0 means none)
43#if PICO_PHEAP_MAX_ENTRIES < 256
44typedef uint8_t pheap_node_id_t;
45#elif PICO_PHEAP_MAX_ENTRIES < 65535
46typedef uint16_t pheap_node_id_t;
47#else
48#error invalid PICO_PHEAP_MAX_ENTRIES
49#endif
50
51typedef struct pheap_node {
52 pheap_node_id_t child, sibling, parent;
54
61typedef bool (*pheap_comparator)(void *user_data, pheap_node_id_t a, pheap_node_id_t b);
62
63typedef struct pheap {
64 pheap_node_t *nodes;
65 pheap_comparator comparator;
66 void *user_data;
67 pheap_node_id_t max_nodes;
68 pheap_node_id_t root_id;
69 // we remove from head and add to tail to stop reusing the same ids
70 pheap_node_id_t free_head_id;
71 pheap_node_id_t free_tail_id;
72} pheap_t;
73
88pheap_t *ph_create(uint max_nodes, pheap_comparator comparator, void *user_data);
89
95void ph_clear(pheap_t *heap);
96
104void ph_destroy(pheap_t *heap);
105
106// internal method
107static inline pheap_node_t *ph_get_node(pheap_t *heap, pheap_node_id_t id) {
108 assert(id && id <= heap->max_nodes);
109 return heap->nodes + id - 1;
110}
111
112// internal method
113static void ph_add_child_node(pheap_t *heap, pheap_node_id_t parent_id, pheap_node_id_t child_id) {
114 pheap_node_t *n = ph_get_node(heap, parent_id);
115 assert(parent_id);
116 assert(child_id);
117 assert(parent_id != child_id);
118 pheap_node_t *c = ph_get_node(heap, child_id);
119 c->parent = parent_id;
120 if (!n->child) {
121 n->child = child_id;
122 } else {
123 c->sibling = n->child;
124 n->child = child_id;
125 }
126}
127
128// internal method
129static pheap_node_id_t ph_merge_nodes(pheap_t *heap, pheap_node_id_t a, pheap_node_id_t b) {
130 if (!a) return b;
131 if (!b) return a;
132 if (heap->comparator(heap->user_data, a, b)) {
133 ph_add_child_node(heap, a, b);
134 return a;
135 } else {
136 ph_add_child_node(heap, b, a);
137 return b;
138 }
139}
140
148static inline pheap_node_id_t ph_new_node(pheap_t *heap) {
149 if (!heap->free_head_id) return 0;
150 pheap_node_id_t id = heap->free_head_id;
151 pheap_node_t *hn = ph_get_node(heap, id);
152 heap->free_head_id = hn->sibling;
153 if (!heap->free_head_id) heap->free_tail_id = 0;
154 hn->child = hn->sibling = hn->parent = 0;
155 return id;
156}
157
170static inline pheap_node_id_t ph_insert_node(pheap_t *heap, pheap_node_id_t id) {
171 assert(id);
172 pheap_node_t *hn = ph_get_node(heap, id);
173 hn->child = hn->sibling = hn->parent = 0;
174 heap->root_id = ph_merge_nodes(heap, heap->root_id, id);
175 return heap->root_id;
176}
177
186static inline pheap_node_id_t ph_peek_head(pheap_t *heap) {
187 return heap->root_id;
188}
189
206pheap_node_id_t ph_remove_head(pheap_t *heap, bool free);
207
221static inline pheap_node_id_t ph_remove_and_free_head(pheap_t *heap) {
222 return ph_remove_head(heap, true);
223}
224
234bool ph_remove_and_free_node(pheap_t *heap, pheap_node_id_t id);
235
245static inline bool ph_contains_node(pheap_t *heap, pheap_node_id_t id) {
246 return id == heap->root_id || ph_get_node(heap, id)->parent;
247}
248
249
257static inline void ph_free_node(pheap_t *heap, pheap_node_id_t id) {
258 assert(id && !ph_contains_node(heap, id));
259 if (heap->free_tail_id) {
260 ph_get_node(heap, heap->free_tail_id)->sibling = id;
261 }
262 if (!heap->free_head_id) {
263 assert(!heap->free_tail_id);
264 heap->free_head_id = id;
265 }
266 heap->free_tail_id = id;
267}
268
277void ph_dump(pheap_t *heap, void (*dump_key)(pheap_node_id_t id, void *user_data), void *user_data);
278
289void ph_post_alloc_init(pheap_t *heap, uint max_nodes, pheap_comparator comparator, void *user_data);
290
296#define PHEAP_DEFINE_STATIC(name, _max_nodes) \
297 static_assert(_max_nodes && _max_nodes < (1u << (8 * sizeof(pheap_node_id_t))), ""); \
298 static pheap_node_t name ## _nodes[_max_nodes]; \
299 static pheap_t name = { \
300 .nodes = name ## _nodes, \
301 .max_nodes = _max_nodes \
302 };
303
304
305#ifdef __cplusplus
306}
307#endif
308
309#endif
bool(* pheap_comparator)(void *user_data, pheap_node_id_t a, pheap_node_id_t b)
A user comparator function for nodes in a pairing heap.
Definition pheap.h:61
void ph_destroy(pheap_t *heap)
De-allocates a pairing heap.
Definition pheap.c:37
static void ph_free_node(pheap_t *heap, pheap_node_id_t id)
Free a node that is not currently in the heap, but has been allocated.
Definition pheap.h:257
void ph_clear(pheap_t *heap)
Removes all nodes from the pairing heap.
Definition pheap.c:27
void ph_post_alloc_init(pheap_t *heap, uint max_nodes, pheap_comparator comparator, void *user_data)
Initialize a statically allocated heap (ph_create() using the C heap). The heap member nodes must be ...
Definition pheap.c:19
static bool ph_contains_node(pheap_t *heap, pheap_node_id_t id)
Determine if the heap contains a given node. Note containment refers to whether the node is inserted ...
Definition pheap.h:245
bool ph_remove_and_free_node(pheap_t *heap, pheap_node_id_t id)
Remove and free an arbitrary node from the pairing heap. This is a more costly operation than removin...
Definition pheap.c:82
pheap_node_id_t ph_remove_head(pheap_t *heap, bool free)
Remove the head node from the pairing heap. This head node is the node which compares first in the lo...
Definition pheap.c:76
static pheap_node_id_t ph_peek_head(pheap_t *heap)
Returns the head node in the heap, i.e. the node which compares first, but without removing it from t...
Definition pheap.h:186
void ph_dump(pheap_t *heap, void(*dump_key)(pheap_node_id_t id, void *user_data), void *user_data)
Print a representation of the heap for debugging.
Definition pheap.c:135
static pheap_node_id_t ph_insert_node(pheap_t *heap, pheap_node_id_t id)
Inserts a node into the heap.
Definition pheap.h:170
pheap_t * ph_create(uint max_nodes, pheap_comparator comparator, void *user_data)
Create a pairing heap, which effectively maintains an efficient sorted ordering of nodes....
Definition pheap.c:11
static pheap_node_id_t ph_remove_and_free_head(pheap_t *heap)
Remove the head node from the pairing heap. This head node is the node which compares first in the lo...
Definition pheap.h:221
static pheap_node_id_t ph_new_node(pheap_t *heap)
Allocate a new node from the unused space in the heap.
Definition pheap.h:148
Definition pheap.h:51
Definition pheap.h:63