mirror of
https://github.com/yuzu-mirror/yuzu.git
synced 2024-11-06 06:29:57 +00:00
99ceb03a1c
This formats all copyright comments according to SPDX formatting guidelines. Additionally, this resolves the remaining GPLv2 only licensed files by relicensing them to GPLv2.0-or-later.
117 lines
4.2 KiB
C++
117 lines
4.2 KiB
C++
// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
|
|
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
|
|
#pragma once
|
|
|
|
#include <algorithm>
|
|
#include <array>
|
|
#include <atomic>
|
|
#include <cstddef>
|
|
#include <cstring>
|
|
#include <new>
|
|
#include <type_traits>
|
|
#include <vector>
|
|
|
|
namespace Common {
|
|
|
|
/// SPSC ring buffer
|
|
/// @tparam T Element type
|
|
/// @tparam capacity Number of slots in ring buffer
|
|
template <typename T, std::size_t capacity>
|
|
class RingBuffer {
|
|
/// A "slot" is made of a single `T`.
|
|
static constexpr std::size_t slot_size = sizeof(T);
|
|
// T must be safely memcpy-able and have a trivial default constructor.
|
|
static_assert(std::is_trivial_v<T>);
|
|
// Ensure capacity is sensible.
|
|
static_assert(capacity < std::numeric_limits<std::size_t>::max() / 2);
|
|
static_assert((capacity & (capacity - 1)) == 0, "capacity must be a power of two");
|
|
// Ensure lock-free.
|
|
static_assert(std::atomic_size_t::is_always_lock_free);
|
|
|
|
public:
|
|
/// Pushes slots into the ring buffer
|
|
/// @param new_slots Pointer to the slots to push
|
|
/// @param slot_count Number of slots to push
|
|
/// @returns The number of slots actually pushed
|
|
std::size_t Push(const void* new_slots, std::size_t slot_count) {
|
|
const std::size_t write_index = m_write_index.load();
|
|
const std::size_t slots_free = capacity + m_read_index.load() - write_index;
|
|
const std::size_t push_count = std::min(slot_count, slots_free);
|
|
|
|
const std::size_t pos = write_index % capacity;
|
|
const std::size_t first_copy = std::min(capacity - pos, push_count);
|
|
const std::size_t second_copy = push_count - first_copy;
|
|
|
|
const char* in = static_cast<const char*>(new_slots);
|
|
std::memcpy(m_data.data() + pos, in, first_copy * slot_size);
|
|
in += first_copy * slot_size;
|
|
std::memcpy(m_data.data(), in, second_copy * slot_size);
|
|
|
|
m_write_index.store(write_index + push_count);
|
|
|
|
return push_count;
|
|
}
|
|
|
|
std::size_t Push(const std::vector<T>& input) {
|
|
return Push(input.data(), input.size());
|
|
}
|
|
|
|
/// Pops slots from the ring buffer
|
|
/// @param output Where to store the popped slots
|
|
/// @param max_slots Maximum number of slots to pop
|
|
/// @returns The number of slots actually popped
|
|
std::size_t Pop(void* output, std::size_t max_slots = ~std::size_t(0)) {
|
|
const std::size_t read_index = m_read_index.load();
|
|
const std::size_t slots_filled = m_write_index.load() - read_index;
|
|
const std::size_t pop_count = std::min(slots_filled, max_slots);
|
|
|
|
const std::size_t pos = read_index % capacity;
|
|
const std::size_t first_copy = std::min(capacity - pos, pop_count);
|
|
const std::size_t second_copy = pop_count - first_copy;
|
|
|
|
char* out = static_cast<char*>(output);
|
|
std::memcpy(out, m_data.data() + pos, first_copy * slot_size);
|
|
out += first_copy * slot_size;
|
|
std::memcpy(out, m_data.data(), second_copy * slot_size);
|
|
|
|
m_read_index.store(read_index + pop_count);
|
|
|
|
return pop_count;
|
|
}
|
|
|
|
std::vector<T> Pop(std::size_t max_slots = ~std::size_t(0)) {
|
|
std::vector<T> out(std::min(max_slots, capacity));
|
|
const std::size_t count = Pop(out.data(), out.size());
|
|
out.resize(count);
|
|
return out;
|
|
}
|
|
|
|
/// @returns Number of slots used
|
|
[[nodiscard]] std::size_t Size() const {
|
|
return m_write_index.load() - m_read_index.load();
|
|
}
|
|
|
|
/// @returns Maximum size of ring buffer
|
|
[[nodiscard]] constexpr std::size_t Capacity() const {
|
|
return capacity;
|
|
}
|
|
|
|
private:
|
|
// It is important to align the below variables for performance reasons:
|
|
// Having them on the same cache-line would result in false-sharing between them.
|
|
// TODO: Remove this ifdef whenever clang and GCC support
|
|
// std::hardware_destructive_interference_size.
|
|
#if defined(_MSC_VER) && _MSC_VER >= 1911
|
|
alignas(std::hardware_destructive_interference_size) std::atomic_size_t m_read_index{0};
|
|
alignas(std::hardware_destructive_interference_size) std::atomic_size_t m_write_index{0};
|
|
#else
|
|
alignas(128) std::atomic_size_t m_read_index{0};
|
|
alignas(128) std::atomic_size_t m_write_index{0};
|
|
#endif
|
|
|
|
std::array<T, capacity> m_data;
|
|
};
|
|
|
|
} // namespace Common
|