mirror of https://github.com/bsnes-emu/bsnes.git
111 lines
2.7 KiB
C++
111 lines
2.7 KiB
C++
#ifndef NALL_PRIORITY_QUEUE_HPP
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#define NALL_PRIORITY_QUEUE_HPP
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#include <limits>
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#include <nall/function.hpp>
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#include <nall/serializer.hpp>
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#include <nall/utility.hpp>
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namespace nall {
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template<typename type_t> void priority_queue_nocallback(type_t) {}
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//priority queue implementation using binary min-heap array;
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//does not require normalize() function.
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//O(1) find (tick)
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//O(log n) append (enqueue)
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//O(log n) remove (dequeue)
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template<typename type_t> struct priority_queue {
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inline void tick(unsigned ticks) {
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basecounter += ticks;
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while(heapsize && gte(basecounter, heap[0].counter)) callback(dequeue());
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}
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//counter is relative to current time (eg enqueue(64, ...) fires in 64 ticks);
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//counter cannot exceed std::numeric_limits<unsigned>::max() >> 1.
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void enqueue(unsigned counter, type_t event) {
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unsigned child = heapsize++;
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counter += basecounter;
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while(child) {
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unsigned parent = (child - 1) >> 1;
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if(gte(counter, heap[parent].counter)) break;
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heap[child].counter = heap[parent].counter;
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heap[child].event = heap[parent].event;
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child = parent;
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}
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heap[child].counter = counter;
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heap[child].event = event;
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}
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type_t dequeue() {
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type_t event(heap[0].event);
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unsigned parent = 0;
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unsigned counter = heap[--heapsize].counter;
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while(true) {
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unsigned child = (parent << 1) + 1;
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if(child >= heapsize) break;
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if(child + 1 < heapsize && gte(heap[child].counter, heap[child + 1].counter)) child++;
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if(gte(heap[child].counter, counter)) break;
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heap[parent].counter = heap[child].counter;
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heap[parent].event = heap[child].event;
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parent = child;
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}
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heap[parent].counter = counter;
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heap[parent].event = heap[heapsize].event;
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return event;
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}
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void reset() {
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basecounter = 0;
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heapsize = 0;
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}
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void serialize(serializer& s) {
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s.integer(basecounter);
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s.integer(heapsize);
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for(unsigned n = 0; n < heapcapacity; n++) {
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s.integer(heap[n].counter);
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s.integer(heap[n].event);
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}
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}
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priority_queue(unsigned size, function<void (type_t)> callback = &priority_queue_nocallback<type_t>)
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: callback(callback) {
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heap = new heap_t[size];
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heapcapacity = size;
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reset();
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}
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~priority_queue() {
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delete[] heap;
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}
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priority_queue& operator=(const priority_queue&) = delete;
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priority_queue(const priority_queue&) = delete;
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private:
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function<void (type_t)> callback;
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unsigned basecounter;
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unsigned heapsize;
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unsigned heapcapacity;
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struct heap_t {
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unsigned counter;
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type_t event;
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} *heap;
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//return true if x is greater than or equal to y
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inline bool gte(unsigned x, unsigned y) {
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return x - y < (std::numeric_limits<unsigned>::max() >> 1);
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}
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};
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}
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#endif
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