No malloc for default alarm pool an pheap docs/cleanup (#143)

* Statically allocate the default timer pool (to avoid pulling in malloc); doxygen for pheap (and some function name changes)

* fix comments
This commit is contained in:
Graham Sanderson 2021-02-25 08:40:03 -06:00 committed by graham sanderson
parent 0a22f704a6
commit e730e03e7f
3 changed files with 225 additions and 57 deletions

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@ -33,26 +33,25 @@ typedef struct alarm_pool {
} alarm_pool_t; } alarm_pool_t;
#if !PICO_TIME_DEFAULT_ALARM_POOL_DISABLED #if !PICO_TIME_DEFAULT_ALARM_POOL_DISABLED
static alarm_pool_t *default_alarm_pool; // To avoid bringing in calloc, we statically allocate the arrays and the heap
PHEAP_DEFINE_STATIC(default_alarm_pool_heap, PICO_TIME_DEFAULT_ALARM_POOL_MAX_TIMERS);
static alarm_pool_entry_t default_alarm_pool_entries[PICO_TIME_DEFAULT_ALARM_POOL_MAX_TIMERS];
static uint8_t default_alarm_pool_entry_ids_high[PICO_TIME_DEFAULT_ALARM_POOL_MAX_TIMERS];
static alarm_pool_t default_alarm_pool = {
.heap = &default_alarm_pool_heap,
.entries = default_alarm_pool_entries,
.entry_ids_high = default_alarm_pool_entry_ids_high,
};
static inline bool default_alarm_pool_initialized(void) {
return default_alarm_pool.lock != NULL;
}
#endif #endif
static alarm_pool_t *pools[NUM_TIMERS]; static alarm_pool_t *pools[NUM_TIMERS];
static void alarm_pool_post_alloc_init(alarm_pool_t *pool, uint hardware_alarm_num);
void alarm_pool_init_default() {
#if !PICO_TIME_DEFAULT_ALARM_POOL_DISABLED
// allow multiple calls for ease of use from host tests
if (!default_alarm_pool) {
default_alarm_pool = alarm_pool_create(PICO_TIME_DEFAULT_ALARM_POOL_HARDWARE_ALARM_NUM,
PICO_TIME_DEFAULT_ALARM_POOL_MAX_TIMERS);
}
#endif
}
#if !PICO_TIME_DEFAULT_ALARM_POOL_DISABLED
alarm_pool_t *alarm_pool_get_default() {
assert(default_alarm_pool);
return default_alarm_pool;
}
#endif
static inline alarm_pool_entry_t *get_entry(alarm_pool_t *pool, pheap_node_id_t id) { static inline alarm_pool_entry_t *get_entry(alarm_pool_t *pool, pheap_node_id_t id) {
assert(id && id <= pool->heap->max_nodes); assert(id && id <= pool->heap->max_nodes);
@ -73,11 +72,30 @@ static inline alarm_id_t make_public_id(uint8_t id_high, pheap_node_id_t id) {
return (alarm_id_t)(((uint)id_high << 8u * sizeof(id)) | id); return (alarm_id_t)(((uint)id_high << 8u * sizeof(id)) | id);
} }
void alarm_pool_init_default() {
#if !PICO_TIME_DEFAULT_ALARM_POOL_DISABLED
// allow multiple calls for ease of use from host tests
if (!default_alarm_pool_initialized()) {
ph_post_alloc_init(default_alarm_pool.heap, PICO_TIME_DEFAULT_ALARM_POOL_MAX_TIMERS,
timer_pool_entry_comparator, &default_alarm_pool);
alarm_pool_post_alloc_init(&default_alarm_pool,
PICO_TIME_DEFAULT_ALARM_POOL_HARDWARE_ALARM_NUM);
}
#endif
}
#if !PICO_TIME_DEFAULT_ALARM_POOL_DISABLED
alarm_pool_t *alarm_pool_get_default() {
assert(default_alarm_pool_initialized());
return &default_alarm_pool;
}
#endif
static pheap_node_id_t add_alarm_under_lock(alarm_pool_t *pool, absolute_time_t time, alarm_callback_t callback, static pheap_node_id_t add_alarm_under_lock(alarm_pool_t *pool, absolute_time_t time, alarm_callback_t callback,
void *user_data, pheap_node_id_t reuse_id, bool create_if_past, bool *missed) { void *user_data, pheap_node_id_t reuse_id, bool create_if_past, bool *missed) {
pheap_node_id_t id; pheap_node_id_t id;
if (reuse_id) { if (reuse_id) {
assert(!ph_contains(pool->heap, reuse_id)); assert(!ph_contains_node(pool->heap, reuse_id));
id = reuse_id; id = reuse_id;
} else { } else {
id = ph_new_node(pool->heap); id = ph_new_node(pool->heap);
@ -87,10 +105,10 @@ static pheap_node_id_t add_alarm_under_lock(alarm_pool_t *pool, absolute_time_t
entry->target = time; entry->target = time;
entry->callback = callback; entry->callback = callback;
entry->user_data = user_data; entry->user_data = user_data;
if (id == ph_insert(pool->heap, id)) { if (id == ph_insert_node(pool->heap, id)) {
bool is_missed = hardware_alarm_set_target(pool->hardware_alarm_num, time); bool is_missed = hardware_alarm_set_target(pool->hardware_alarm_num, time);
if (is_missed && !create_if_past) { if (is_missed && !create_if_past) {
ph_delete(pool->heap, id); ph_remove_and_free_node(pool->heap, id);
} }
if (missed) *missed = is_missed; if (missed) *missed = is_missed;
} }
@ -114,8 +132,8 @@ static void alarm_pool_alarm_callback(uint alarm_num) {
if (next_id) { if (next_id) {
alarm_pool_entry_t *entry = get_entry(pool, next_id); alarm_pool_entry_t *entry = get_entry(pool, next_id);
if (absolute_time_diff_us(now, entry->target) <= 0) { if (absolute_time_diff_us(now, entry->target) <= 0) {
// we reserve the id in case we need to re-add the timer // we don't free the id in case we need to re-add the timer
pheap_node_id_t __unused removed_id = ph_remove_head_reserve(pool->heap, true); pheap_node_id_t __unused removed_id = ph_remove_head(pool->heap, false);
assert(removed_id == next_id); // will be true under lock assert(removed_id == next_id); // will be true under lock
target = entry->target; target = entry->target;
callback = entry->callback; callback = entry->callback;
@ -143,7 +161,7 @@ static void alarm_pool_alarm_callback(uint alarm_num) {
true, NULL); true, NULL);
} else { } else {
// need to return the id to the heap // need to return the id to the heap
ph_add_to_free_list(pool->heap, next_id); ph_free_node(pool->heap, next_id);
(*get_entry_id_high(pool, next_id))++; // we bump it for next use of id (*get_entry_id_high(pool, next_id))++; // we bump it for next use of id
} }
pool->alarm_in_progress = 0; pool->alarm_in_progress = 0;
@ -155,20 +173,30 @@ static void alarm_pool_alarm_callback(uint alarm_num) {
// note the timer is create with IRQs on this core // note the timer is create with IRQs on this core
alarm_pool_t *alarm_pool_create(uint hardware_alarm_num, uint max_timers) { alarm_pool_t *alarm_pool_create(uint hardware_alarm_num, uint max_timers) {
hardware_alarm_claim(hardware_alarm_num); alarm_pool_t *pool = (alarm_pool_t *) malloc(sizeof(alarm_pool_t));
hardware_alarm_cancel(hardware_alarm_num);
hardware_alarm_set_callback(hardware_alarm_num, alarm_pool_alarm_callback);
alarm_pool_t *pool = (alarm_pool_t *)malloc(sizeof(alarm_pool_t));
pool->lock = spin_lock_instance(next_striped_spin_lock_num());
pool->heap = ph_create(max_timers, timer_pool_entry_comparator, pool); pool->heap = ph_create(max_timers, timer_pool_entry_comparator, pool);
pool->entries = (alarm_pool_entry_t *)calloc(max_timers, sizeof(alarm_pool_entry_t)); pool->entries = (alarm_pool_entry_t *)calloc(max_timers, sizeof(alarm_pool_entry_t));
pool->entry_ids_high = (uint8_t *)calloc(max_timers, sizeof(uint8_t)); pool->entry_ids_high = (uint8_t *)calloc(max_timers, sizeof(uint8_t));
pool->hardware_alarm_num = (uint8_t)hardware_alarm_num; alarm_pool_post_alloc_init(pool, hardware_alarm_num);
pools[hardware_alarm_num] = pool;
return pool; return pool;
} }
void alarm_pool_post_alloc_init(alarm_pool_t *pool, uint hardware_alarm_num) {
hardware_alarm_claim(hardware_alarm_num);
hardware_alarm_cancel(hardware_alarm_num);
hardware_alarm_set_callback(hardware_alarm_num, alarm_pool_alarm_callback);
pool->lock = spin_lock_instance(next_striped_spin_lock_num());
pool->hardware_alarm_num = (uint8_t) hardware_alarm_num;
pools[hardware_alarm_num] = pool;
}
void alarm_pool_destroy(alarm_pool_t *pool) { void alarm_pool_destroy(alarm_pool_t *pool) {
#if !PICO_TIME_DEFAULT_ALARM_POOL_DISABLED
if (pool == &default_alarm_pool) {
assert(false); // attempt to delete default alarm pool
return;
}
#endif
assert(pools[pool->hardware_alarm_num] == pool); assert(pools[pool->hardware_alarm_num] == pool);
pools[pool->hardware_alarm_num] = NULL; pools[pool->hardware_alarm_num] = NULL;
// todo clear out timers // todo clear out timers
@ -219,12 +247,12 @@ bool alarm_pool_cancel_alarm(alarm_pool_t *pool, alarm_id_t alarm_id) {
bool rc = false; bool rc = false;
uint32_t save = spin_lock_blocking(pool->lock); uint32_t save = spin_lock_blocking(pool->lock);
pheap_node_id_t id = (pheap_node_id_t) alarm_id; pheap_node_id_t id = (pheap_node_id_t) alarm_id;
if (ph_contains(pool->heap, id)) { if (ph_contains_node(pool->heap, id)) {
assert(alarm_id != pool->alarm_in_progress); // it shouldn't be in the heap if it is in progress assert(alarm_id != pool->alarm_in_progress); // it shouldn't be in the heap if it is in progress
// check we have the right high value // check we have the right high value
uint8_t id_high = (uint8_t)((uint)alarm_id >> 8u * sizeof(pheap_node_id_t)); uint8_t id_high = (uint8_t)((uint)alarm_id >> 8u * sizeof(pheap_node_id_t));
if (id_high == *get_entry_id_high(pool, id)) { if (id_high == *get_entry_id_high(pool, id)) {
rc = ph_delete(pool->heap, id); rc = ph_remove_and_free_node(pool->heap, id);
// note we don't bother to remove the actual hardware alarm timeout... // note we don't bother to remove the actual hardware alarm timeout...
// it will either do callbacks or not depending on other alarms, and reset the next timeout itself // it will either do callbacks or not depending on other alarms, and reset the next timeout itself
assert(rc); assert(rc);

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@ -29,7 +29,7 @@ extern "C" {
* *
* NOTE: this class is not safe for concurrent usage. It should be externally protected. Furthermore * NOTE: this class is not safe for concurrent usage. It should be externally protected. Furthermore
* if used concurrently, the caller needs to protect around their use of the returned id. * if used concurrently, the caller needs to protect around their use of the returned id.
* for example, ph_remove_head returns the id of an element that is no longer in the heap. * for example, ph_remove_and_free_head returns the id of an element that is no longer in the heap.
* *
* The user can still use this to look at the data in their companion array, however obviously further operations * The user can still use this to look at the data in their companion array, however obviously further operations
* on the heap may cause them to overwrite that data as the id may be reused on subsequent operations * on the heap may cause them to overwrite that data as the id may be reused on subsequent operations
@ -53,7 +53,11 @@ typedef struct pheap_node {
pheap_node_id_t child, sibling, parent; pheap_node_id_t child, sibling, parent;
} pheap_node_t; } pheap_node_t;
// return true if a < b in natural order /**
* A user comparator function for nodes in a pairing heap.
*
* \return true if a < b in natural order. Note this relative ordering must be stable from call to call.
*/
typedef bool (*pheap_comparator)(void *user_data, pheap_node_id_t a, pheap_node_id_t b); typedef bool (*pheap_comparator)(void *user_data, pheap_node_id_t a, pheap_node_id_t b);
typedef struct pheap { typedef struct pheap {
@ -67,17 +71,42 @@ typedef struct pheap {
pheap_node_id_t free_tail_id; pheap_node_id_t free_tail_id;
} pheap_t; } pheap_t;
/**
* Create a pairing heap, which effectively maintains an efficient sorted ordering
* of nodes. The heap itself stores no user per-node state, it is expected
* that the user maintains a companion array. A comparator function must
* be provided so that the heap implementation can determine the relative ordering of nodes
*
* \param max_nodes the maximum number of nodes that may be in the heap (this is bounded by
* PICO_PHEAP_MAX_ENTRIES which defaults to 255 to be able to store indexes
* in a single byte).
* \param comparator the node comparison function
* \param user_data a user data pointer associated with the heap that is provided in callbacks
* \return a newly allocated and initialized heap
*/
pheap_t *ph_create(uint max_nodes, pheap_comparator comparator, void *user_data); pheap_t *ph_create(uint max_nodes, pheap_comparator comparator, void *user_data);
/**
* Removes all nodes from the pairing heap
* \param heap the heap
*/
void ph_clear(pheap_t *heap); void ph_clear(pheap_t *heap);
/**
* De-allocates a pairing heap
*
* Note this method must *ONLY* be called on heaps created by ph_create()
* \param heap the heap
*/
void ph_destroy(pheap_t *heap); void ph_destroy(pheap_t *heap);
// internal method
static inline pheap_node_t *ph_get_node(pheap_t *heap, pheap_node_id_t id) { static inline pheap_node_t *ph_get_node(pheap_t *heap, pheap_node_id_t id) {
assert(id && id <= heap->max_nodes); assert(id && id <= heap->max_nodes);
return heap->nodes + id - 1; return heap->nodes + id - 1;
} }
// internal method
static void ph_add_child_node(pheap_t *heap, pheap_node_id_t parent_id, pheap_node_id_t child_id) { static void ph_add_child_node(pheap_t *heap, pheap_node_id_t parent_id, pheap_node_id_t child_id) {
pheap_node_t *n = ph_get_node(heap, parent_id); pheap_node_t *n = ph_get_node(heap, parent_id);
assert(parent_id); assert(parent_id);
@ -93,6 +122,7 @@ static void ph_add_child_node(pheap_t *heap, pheap_node_id_t parent_id, pheap_no
} }
} }
// internal method
static pheap_node_id_t ph_merge_nodes(pheap_t *heap, pheap_node_id_t a, pheap_node_id_t b) { static pheap_node_id_t ph_merge_nodes(pheap_t *heap, pheap_node_id_t a, pheap_node_id_t b) {
if (!a) return b; if (!a) return b;
if (!b) return a; if (!b) return a;
@ -105,17 +135,34 @@ static pheap_node_id_t ph_merge_nodes(pheap_t *heap, pheap_node_id_t a, pheap_no
} }
} }
/**
* Allocate a new node from the unused space in the heap
*
* \param heap the heap
* \return an identifier for the node, or 0 if the heap is full
*/
static inline pheap_node_id_t ph_new_node(pheap_t *heap) { static inline pheap_node_id_t ph_new_node(pheap_t *heap) {
if (!heap->free_head_id) return 0; if (!heap->free_head_id) return 0;
pheap_node_id_t id = heap->free_head_id; pheap_node_id_t id = heap->free_head_id;
heap->free_head_id = ph_get_node(heap, id)->sibling; pheap_node_t *hn = ph_get_node(heap, id);
heap->free_head_id = hn->sibling;
if (!heap->free_head_id) heap->free_tail_id = 0; if (!heap->free_head_id) heap->free_tail_id = 0;
hn->child = hn->sibling = hn->parent = 0;
return id; return id;
} }
// note this will callback the comparator for the node /**
// returns the (new) root of the heap * Inserts a node into the heap.
static inline pheap_node_id_t ph_insert(pheap_t *heap, pheap_node_id_t id) { *
* This method inserts a node (previously allocated by ph_new_node())
* into the heap, determining the correct order by calling
* the heap's comparator
*
* \param heap the heap
* \param id the id of the node to insert
* \return the id of the new head of the pairing heap (i.e. node that compares first)
*/
static inline pheap_node_id_t ph_insert_node(pheap_t *heap, pheap_node_id_t id) {
assert(id); assert(id);
pheap_node_t *hn = ph_get_node(heap, id); pheap_node_t *hn = ph_get_node(heap, id);
hn->child = hn->sibling = hn->parent = 0; hn->child = hn->sibling = hn->parent = 0;
@ -123,31 +170,120 @@ static inline pheap_node_id_t ph_insert(pheap_t *heap, pheap_node_id_t id) {
return heap->root_id; return heap->root_id;
} }
/**
* Returns the head node in the heap, i.e. the node
* which compares first, but without removing it from the heap.
*
* \param heap the heap
* \return the current head node id
*/
static inline pheap_node_id_t ph_peek_head(pheap_t *heap) { static inline pheap_node_id_t ph_peek_head(pheap_t *heap) {
return heap->root_id; return heap->root_id;
} }
pheap_node_id_t ph_remove_head_reserve(pheap_t *heap, bool reserve); /**
* Remove the head node from the pairing heap. This head node is
* the node which compares first in the logical ordering provided
* by the comparator.
*
* Note that in the case of free == true, the returned id is no longer
* allocated and may be re-used by future node allocations, so the caller
* should retrieve any per node state from the companion array before modifying
* the heap further.
*
* @param heap the heap
* @param free true if the id is also to be freed; false if not - useful if the caller
* may wish to re-insert an item with the same id)
* @return the old head node id.
*/
pheap_node_id_t ph_remove_head(pheap_t *heap, bool free);
static inline pheap_node_id_t ph_remove_head(pheap_t *heap) { /**
return ph_remove_head_reserve(heap, false); * Remove the head node from the pairing heap. This head node is
* the node which compares first in the logical ordering provided
* by the comparator.
*
* Note that the returned id will be freed, and thus may be re-used by future node allocations,
* so the caller should retrieve any per node state from the companion array before modifying
* the heap further.
*
* @param heap the heap
* @return the old head node id.
*/
static inline pheap_node_id_t ph_remove_and_free_head(pheap_t *heap) {
return ph_remove_head(heap, true);
} }
static inline bool ph_contains(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 removing the head via ph_remove_and_free_head()
*
* @param heap the heap
* @param id the id of the node to free
* @return true if the the node was in the heap, false otherwise
*/
bool ph_remove_and_free_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 (ph_insert_node()) vs allocated (ph_new_node())
*
* @param heap the heap
* @param id the id of the node
* @return true if the heap contains a node with the given id, false otherwise.
*/
static inline bool ph_contains_node(pheap_t *heap, pheap_node_id_t id) {
return id == heap->root_id || ph_get_node(heap, id)->parent; return id == heap->root_id || ph_get_node(heap, id)->parent;
} }
bool ph_delete(pheap_t *heap, pheap_node_id_t id);
static inline void ph_add_to_free_list(pheap_t *heap, pheap_node_id_t id) { /**
assert(id && !ph_contains(heap, id)); * Free a node that is not currently in the heap, but has been allocated
*
* @param heap the heap
* @param id the id of the node
*/
static inline void ph_free_node(pheap_t *heap, pheap_node_id_t id) {
assert(id && !ph_contains_node(heap, id));
if (heap->free_tail_id) { if (heap->free_tail_id) {
ph_get_node(heap, heap->free_tail_id)->sibling = id; ph_get_node(heap, heap->free_tail_id)->sibling = id;
} }
heap->free_tail_id = id; heap->free_tail_id = id;
} }
void ph_dump(pheap_t *heap, void (*dump_key)(pheap_node_id_t, void *), void *user_data); /**
* Print a representation of the heap for debugging
*
* @param heap the heap
* @param dump_key a method to print a node value
* @param user_data the user data to pass to the dump_key method
*/
void ph_dump(pheap_t *heap, void (*dump_key)(pheap_node_id_t id, void *user_data), void *user_data);
/**
* Initialize a statically allocated heap (ph_create() using the C heap).
* The heap member `nodes` must be allocated of size max_nodes.
*
* @param heap the heap
* @param max_nodes the max number of nodes in the heap (matching the size of the heap's nodes array)
* @param comparator the comparator for the heap
* @param user_data the user data for the heap.
*/
void ph_post_alloc_init(pheap_t *heap, uint max_nodes, pheap_comparator comparator, void *user_data);
/**
* Define a statically allocated pairing heap. This must be initialized
* by ph_post_alloc_init
*/
#define PHEAP_DEFINE_STATIC(name, _max_nodes) \
static_assert(_max_nodes && _max_nodes < (1u << (8 * sizeof(pheap_node_id_t))), ""); \
static pheap_node_t name ## _nodes[_max_nodes]; \
static pheap_t name = { \
.nodes = name ## _nodes, \
.max_nodes = _max_nodes \
};
#ifdef __cplusplus #ifdef __cplusplus
} }
#endif #endif

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@ -9,14 +9,19 @@
#include "pico/util/pheap.h" #include "pico/util/pheap.h"
pheap_t *ph_create(uint max_nodes, pheap_comparator comparator, void *user_data) { pheap_t *ph_create(uint max_nodes, pheap_comparator comparator, void *user_data) {
invalid_params_if(PHEAP, !max_nodes || max_nodes >= (1u << sizeof(pheap_node_id_t))); invalid_params_if(PHEAP, !max_nodes || max_nodes >= (1u << (8 * sizeof(pheap_node_id_t))));
pheap_t *heap = calloc(1, sizeof(pheap_t)); pheap_t *heap = calloc(1, sizeof(pheap_t));
heap->nodes = calloc(max_nodes, sizeof(pheap_node_t));
ph_post_alloc_init(heap, max_nodes, comparator, user_data);
return heap;
}
void ph_post_alloc_init(pheap_t *heap, uint max_nodes, pheap_comparator comparator, void *user_data) {
invalid_params_if(PHEAP, !max_nodes || max_nodes >= (1u << (8 * sizeof(pheap_node_id_t))));
heap->max_nodes = (pheap_node_id_t) max_nodes; heap->max_nodes = (pheap_node_id_t) max_nodes;
heap->comparator = comparator; heap->comparator = comparator;
heap->nodes = calloc(max_nodes, sizeof(pheap_node_t));
heap->user_data = user_data; heap->user_data = user_data;
ph_clear(heap); ph_clear(heap);
return heap;
} }
void ph_clear(pheap_t *heap) { void ph_clear(pheap_t *heap) {
@ -47,13 +52,13 @@ pheap_node_id_t ph_merge_two_pass(pheap_t *heap, pheap_node_id_t id) {
} }
} }
static pheap_node_id_t ph_remove_any_head(pheap_t *heap, pheap_node_id_t root_id, bool reserve) { static pheap_node_id_t ph_remove_any_head(pheap_t *heap, pheap_node_id_t root_id, bool free) {
assert(root_id); assert(root_id);
// printf("Removing head %d (parent %d sibling %d)\n", root_id, ph_get_node(heap, root_id)->parent, ph_get_node(heap, root_id)->sibling); // printf("Removing head %d (parent %d sibling %d)\n", root_id, ph_get_node(heap, root_id)->parent, ph_get_node(heap, root_id)->sibling);
assert(!ph_get_node(heap, root_id)->sibling); assert(!ph_get_node(heap, root_id)->sibling);
assert(!ph_get_node(heap, root_id)->parent); assert(!ph_get_node(heap, root_id)->parent);
pheap_node_id_t new_root_id = ph_merge_two_pass(heap, ph_get_node(heap, root_id)->child); pheap_node_id_t new_root_id = ph_merge_two_pass(heap, ph_get_node(heap, root_id)->child);
if (!reserve) { if (free) {
if (heap->free_tail_id) { if (heap->free_tail_id) {
ph_get_node(heap, heap->free_tail_id)->sibling = root_id; ph_get_node(heap, heap->free_tail_id)->sibling = root_id;
} }
@ -64,18 +69,17 @@ static pheap_node_id_t ph_remove_any_head(pheap_t *heap, pheap_node_id_t root_id
return new_root_id; return new_root_id;
} }
pheap_node_id_t ph_remove_head_reserve(pheap_t *heap, bool reserve) { pheap_node_id_t ph_remove_head(pheap_t *heap, bool free) {
pheap_node_id_t old_root_id = ph_peek_head(heap); pheap_node_id_t old_root_id = ph_peek_head(heap);
heap->root_id = ph_remove_any_head(heap, old_root_id, reserve); heap->root_id = ph_remove_any_head(heap, old_root_id, free);
return old_root_id; return old_root_id;
} }
#include <stdio.h> bool ph_remove_and_free_node(pheap_t *heap, pheap_node_id_t id) {
bool ph_delete(pheap_t *heap, pheap_node_id_t id) {
// 1) trivial cases // 1) trivial cases
if (!id) return false; if (!id) return false;
if (id == heap->root_id) { if (id == heap->root_id) {
ph_remove_head(heap); ph_remove_and_free_head(heap);
return true; return true;
} }
// 2) unlink the node from the tree // 2) unlink the node from the tree
@ -101,7 +105,7 @@ bool ph_delete(pheap_t *heap, pheap_node_id_t id) {
node->sibling = node->parent = 0; node->sibling = node->parent = 0;
// ph_dump(heap, NULL, NULL); // ph_dump(heap, NULL, NULL);
// 3) remove it from the head of its own subtree // 3) remove it from the head of its own subtree
pheap_node_id_t new_sub_tree = ph_remove_any_head(heap, id, false); pheap_node_id_t new_sub_tree = ph_remove_any_head(heap, id, true);
assert(new_sub_tree != heap->root_id); assert(new_sub_tree != heap->root_id);
heap->root_id = ph_merge_nodes(heap, heap->root_id, new_sub_tree); heap->root_id = ph_merge_nodes(heap, heap->root_id, new_sub_tree);
return true; return true;