67 lines
1.3 KiB
C++
67 lines
1.3 KiB
C++
#pragma once
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//single-producer, single-consumer lockless queue
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//includes await functions for spin-loops
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namespace nall {
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template<typename T> struct queue_spsc;
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template<typename T, u32 Size>
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struct queue_spsc<T[Size]> {
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auto flush() -> void {
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_read = 0;
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_write = 2 * Size;
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}
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auto size() const -> u32 {
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return (_write - _read) % (2 * Size);
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}
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auto empty() const -> bool {
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return size() == 0;
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}
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auto full() const -> bool {
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return size() == Size;
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}
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auto read() -> maybe<T> {
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if(empty()) return nothing;
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auto value = _data[_read % Size];
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_read = _read + 1 < 2 * Size ? _read + 1 : 0;
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return value;
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}
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auto write(const T& value) -> bool {
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if(full()) return false;
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_data[_write % Size] = value;
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_write = _write + 1 < 4 * Size ? _write + 1 : 2 * Size;
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return true;
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}
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auto await_empty() -> void {
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while(!empty()) spinloop();
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}
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auto await_read() -> T {
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while(empty()) spinloop();
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auto value = _data[_read % Size];
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_read = _read + 1 < 2 * Size ? _read + 1 : 0;
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return value;
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}
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auto await_write(const T& value) -> void {
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while(full()) spinloop();
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_data[_write % Size] = value;
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_write = _write + 1 < 4 * Size ? _write + 1 : 2 * Size;
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}
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private:
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T _data[Size];
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std::atomic<u32> _read = 0;
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std::atomic<u32> _write = 2 * Size;
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};
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}
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