v2.0.0
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
51 typedef struct pheap_node {
52 pheap_node_id_t child, sibling, parent;
53} pheap_node_t;
54
60 typedef bool (*pheap_comparator)(void *user_data, pheap_node_id_t a, pheap_node_id_t b);
61
62 typedef struct pheap {
63 pheap_node_t *nodes;
64 pheap_comparator comparator;
65 void *user_data;
66 pheap_node_id_t max_nodes;
67 pheap_node_id_t root_id;
68 // we remove from head and add to tail to stop reusing the same ids
69 pheap_node_id_t free_head_id;
70 pheap_node_id_t free_tail_id;
71} pheap_t;
72
86 pheap_t *ph_create(uint max_nodes, pheap_comparator comparator, void *user_data);
87
92void ph_clear(pheap_t *heap);
93
100void ph_destroy(pheap_t *heap);
101
102// internal method
103static inline pheap_node_t *ph_get_node(pheap_t *heap, pheap_node_id_t id) {
104 assert(id && id <= heap->max_nodes);
105 return heap->nodes + id - 1;
106}
107
108// internal method
109static void ph_add_child_node(pheap_t *heap, pheap_node_id_t parent_id, pheap_node_id_t child_id) {
110 pheap_node_t *n = ph_get_node(heap, parent_id);
111 assert(parent_id);
112 assert(child_id);
113 assert(parent_id != child_id);
114 pheap_node_t *c = ph_get_node(heap, child_id);
115 c->parent = parent_id;
116 if (!n->child) {
117 n->child = child_id;
118 } else {
119 c->sibling = n->child;
120 n->child = child_id;
121 }
122}
123
124// internal method
125static pheap_node_id_t ph_merge_nodes(pheap_t *heap, pheap_node_id_t a, pheap_node_id_t b) {
126 if (!a) return b;
127 if (!b) return a;
128 if (heap->comparator(heap->user_data, a, b)) {
129 ph_add_child_node(heap, a, b);
130 return a;
131 } else {
132 ph_add_child_node(heap, b, a);
133 return b;
134 }
135}
136
143 static inline pheap_node_id_t ph_new_node(pheap_t *heap) {
144 if (!heap->free_head_id) return 0;
145 pheap_node_id_t id = heap->free_head_id;
146 pheap_node_t *hn = ph_get_node(heap, id);
147 heap->free_head_id = hn->sibling;
148 if (!heap->free_head_id) heap->free_tail_id = 0;
149 hn->child = hn->sibling = hn->parent = 0;
150 return id;
151}
152
164 static inline pheap_node_id_t ph_insert_node(pheap_t *heap, pheap_node_id_t id) {
165 assert(id);
166 pheap_node_t *hn = ph_get_node(heap, id);
167 hn->child = hn->sibling = hn->parent = 0;
168 heap->root_id = ph_merge_nodes(heap, heap->root_id, id);
169 return heap->root_id;
170}
171
179 static inline pheap_node_id_t ph_peek_head(pheap_t *heap) {
180 return heap->root_id;
181}
182
198pheap_node_id_t ph_remove_head(pheap_t *heap, bool free);
199
212 static inline pheap_node_id_t ph_remove_and_free_head(pheap_t *heap) {
213 return ph_remove_head(heap, true);
214}
215
224bool ph_remove_and_free_node(pheap_t *heap, pheap_node_id_t id);
225
234 static inline bool ph_contains_node(pheap_t *heap, pheap_node_id_t id) {
235 return id == heap->root_id || ph_get_node(heap, id)->parent;
236}
237
238
245 static inline void ph_free_node(pheap_t *heap, pheap_node_id_t id) {
246 assert(id && !ph_contains_node(heap, id));
247 if (heap->free_tail_id) {
248 ph_get_node(heap, heap->free_tail_id)->sibling = id;
249 }
250 if (!heap->free_head_id) {
251 assert(!heap->free_tail_id);
252 heap->free_head_id = id;
253 }
254 heap->free_tail_id = id;
255}
256
264 void ph_dump(pheap_t *heap, void (*dump_key)(pheap_node_id_t id, void *user_data), void *user_data);
265
275void ph_post_alloc_init(pheap_t *heap, uint max_nodes, pheap_comparator comparator, void *user_data);
276
281#define PHEAP_DEFINE_STATIC(name, _max_nodes) \
282 static_assert(_max_nodes && _max_nodes < (1u << (8 * sizeof(pheap_node_id_t))), ""); \
283 static pheap_node_t name ## _nodes[_max_nodes]; \
284 static pheap_t name = { \
285 .nodes = name ## _nodes, \
286 .max_nodes = _max_nodes \
287 };
288
289
290#ifdef __cplusplus
291}
292#endif
293
294#endif
pheap_comparator
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:60
ph_destroy
void ph_destroy(pheap_t *heap)
De-allocates a pairing heap.
Definition: pheap.c:37
ph_free_node
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:245
ph_clear
void ph_clear(pheap_t *heap)
Removes all nodes from the pairing heap.
Definition: pheap.c:27
ph_post_alloc_init
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
ph_contains_node
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:234
ph_remove_and_free_node
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
ph_remove_head
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
ph_peek_head
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:179
ph_dump
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.
ph_insert_node
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:164
ph_create
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
ph_remove_and_free_head
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:212
ph_new_node
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:143
pico.h
pheap_node
Definition: pheap.h:51
pheap
Definition: pheap.h:62