yuzu/src/common/virtual_buffer.h
Lioncash 412044960a virtual_buffer: Do nothing on resize() calls with same sizes
Prevents us from churning memory by freeing and reallocating a memory
block that would have already been adequate as is.
2020-11-19 07:54:03 -05:00

83 lines
2.2 KiB
C++

// Copyright 2020 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <type_traits>
#include <utility>
namespace Common {
void* AllocateMemoryPages(std::size_t size) noexcept;
void FreeMemoryPages(void* base, std::size_t size) noexcept;
template <typename T>
class VirtualBuffer final {
public:
static_assert(
std::is_trivially_constructible_v<T>,
"T must be trivially constructible, as non-trivial constructors will not be executed "
"with the current allocator");
constexpr VirtualBuffer() = default;
explicit VirtualBuffer(std::size_t count) : alloc_size{count * sizeof(T)} {
base_ptr = reinterpret_cast<T*>(AllocateMemoryPages(alloc_size));
}
~VirtualBuffer() noexcept {
FreeMemoryPages(base_ptr, alloc_size);
}
VirtualBuffer(const VirtualBuffer&) = delete;
VirtualBuffer& operator=(const VirtualBuffer&) = delete;
VirtualBuffer(VirtualBuffer&& other) noexcept
: alloc_size{std::exchange(other.alloc_size, 0)}, base_ptr{std::exchange(other.base_ptr),
nullptr} {}
VirtualBuffer& operator=(VirtualBuffer&& other) noexcept {
alloc_size = std::exchange(other.alloc_size, 0);
base_ptr = std::exchange(other.base_ptr, nullptr);
return *this;
}
void resize(std::size_t count) {
const auto new_size = count * sizeof(T);
if (new_size == alloc_size) {
return;
}
FreeMemoryPages(base_ptr, alloc_size);
alloc_size = new_size;
base_ptr = reinterpret_cast<T*>(AllocateMemoryPages(alloc_size));
}
[[nodiscard]] constexpr const T& operator[](std::size_t index) const {
return base_ptr[index];
}
[[nodiscard]] constexpr T& operator[](std::size_t index) {
return base_ptr[index];
}
[[nodiscard]] constexpr T* data() {
return base_ptr;
}
[[nodiscard]] constexpr const T* data() const {
return base_ptr;
}
[[nodiscard]] constexpr std::size_t size() const {
return alloc_size / sizeof(T);
}
private:
std::size_t alloc_size{};
T* base_ptr{};
};
} // namespace Common