early-access version 1255

src/common/virtual_buffer.h

@@ -0,0 +1,82 @@
+// 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