84 lines
2.1 KiB
C++
84 lines
2.1 KiB
C++
#pragma once
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#include <utility>
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// Fixed-capacity doubly-linked list with an embedded node array and intrusive
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// free list. Used for callback registries (frame callbacks, timers) needing
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// O(1) insert/remove with stable handles, without heap in IRQ-adjacent paths.
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template <typename T, int N>
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struct callback_list {
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struct node {
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T value;
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node* prev = nullptr;
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node* next = nullptr;
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};
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node nodes[N];
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node* free_head = &nodes[0];
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node* head = nullptr;
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callback_list() {
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for (int i = 0; i < N - 1; i++) nodes[i].next = &nodes[i + 1];
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nodes[N - 1].next = nullptr;
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}
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bool empty() const { return head == nullptr; }
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node* insert(T value) {
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if (!free_head) return nullptr;
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node* n = free_head;
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free_head = n->next;
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n->value = std::move(value);
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n->prev = nullptr;
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n->next = head;
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if (head) head->prev = n;
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head = n;
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return n;
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}
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template <typename Less>
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node* insert_sorted(T value, Less&& less) {
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if (!free_head) return nullptr;
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node* n = free_head;
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free_head = n->next;
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n->value = std::move(value);
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if (!head || less(n->value, head->value)) {
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n->prev = nullptr;
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n->next = head;
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if (head) head->prev = n;
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head = n;
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return n;
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}
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node* cur = head;
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while (cur->next && !less(n->value, cur->next->value))
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cur = cur->next;
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n->prev = cur;
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n->next = cur->next;
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if (cur->next) cur->next->prev = n;
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cur->next = n;
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return n;
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}
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void remove(node* n) {
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if (!n) return;
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if (n->prev) n->prev->next = n->next;
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else head = n->next;
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if (n->next) n->next->prev = n->prev;
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n->value = T{};
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n->next = free_head;
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n->prev = nullptr;
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free_head = n;
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}
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node* front() { return head; }
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template <typename Fn>
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void for_each(Fn&& fn) {
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node* cur = head;
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while (cur) {
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node* next = cur->next;
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fn(cur);
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cur = next;
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}
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}
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};
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