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