From b3c8997829ed986c948d195bc1e7c8f66c42755e Mon Sep 17 00:00:00 2001
From: Lioncash <mathew1800@gmail.com>
Date: Tue, 17 Nov 2020 19:58:41 -0500
Subject: page_table: Allow page tables to be moved

Makes page tables and virtual buffers able to be moved, but not copied,
making the interface more flexible.

Previously, with the destructor specified, but no move assignment or
constructor specified, they wouldn't be implicitly generated.
---
 src/common/page_table.cpp     |  2 +-
 src/common/page_table.h       | 10 +++++++++-
 src/common/virtual_buffer.cpp |  4 ++--
 src/common/virtual_buffer.h   | 23 ++++++++++++++++++-----
 4 files changed, 30 insertions(+), 9 deletions(-)

(limited to 'src')

diff --git a/src/common/page_table.cpp b/src/common/page_table.cpp
index e5d3090d5..bccea0894 100644
--- a/src/common/page_table.cpp
+++ b/src/common/page_table.cpp
@@ -8,7 +8,7 @@ namespace Common {
 
 PageTable::PageTable() = default;
 
-PageTable::~PageTable() = default;
+PageTable::~PageTable() noexcept = default;
 
 void PageTable::Resize(std::size_t address_space_width_in_bits, std::size_t page_size_in_bits,
                        bool has_attribute) {
diff --git a/src/common/page_table.h b/src/common/page_table.h
index a5be7a668..9754fabf9 100644
--- a/src/common/page_table.h
+++ b/src/common/page_table.h
@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <tuple>
+
 #include "common/common_types.h"
 #include "common/memory_hook.h"
 #include "common/virtual_buffer.h"
@@ -47,7 +49,13 @@ struct SpecialRegion {
  */
 struct PageTable {
     PageTable();
-    ~PageTable();
+    ~PageTable() noexcept;
+
+    PageTable(const PageTable&) = delete;
+    PageTable& operator=(const PageTable&) = delete;
+
+    PageTable(PageTable&&) noexcept = default;
+    PageTable& operator=(PageTable&&) noexcept = default;
 
     /**
      * Resizes the page table to be able to accomodate enough pages within
diff --git a/src/common/virtual_buffer.cpp b/src/common/virtual_buffer.cpp
index b009cb500..e3ca29258 100644
--- a/src/common/virtual_buffer.cpp
+++ b/src/common/virtual_buffer.cpp
@@ -13,7 +13,7 @@
 
 namespace Common {
 
-void* AllocateMemoryPages(std::size_t size) {
+void* AllocateMemoryPages(std::size_t size) noexcept {
 #ifdef _WIN32
     void* base{VirtualAlloc(nullptr, size, MEM_COMMIT, PAGE_READWRITE)};
 #else
@@ -29,7 +29,7 @@ void* AllocateMemoryPages(std::size_t size) {
     return base;
 }
 
-void FreeMemoryPages(void* base, [[maybe_unused]] std::size_t size) {
+void FreeMemoryPages(void* base, [[maybe_unused]] std::size_t size) noexcept {
     if (!base) {
         return;
     }
diff --git a/src/common/virtual_buffer.h b/src/common/virtual_buffer.h
index 125cb42f0..363913d45 100644
--- a/src/common/virtual_buffer.h
+++ b/src/common/virtual_buffer.h
@@ -4,25 +4,38 @@
 
 #pragma once
 
-#include "common/common_funcs.h"
+#include <utility>
 
 namespace Common {
 
-void* AllocateMemoryPages(std::size_t size);
-void FreeMemoryPages(void* base, std::size_t size);
+void* AllocateMemoryPages(std::size_t size) noexcept;
+void FreeMemoryPages(void* base, std::size_t size) noexcept;
 
 template <typename T>
-class VirtualBuffer final : NonCopyable {
+class VirtualBuffer final {
 public:
     constexpr VirtualBuffer() = default;
     explicit VirtualBuffer(std::size_t count) : alloc_size{count * sizeof(T)} {
         base_ptr = reinterpret_cast<T*>(AllocateMemoryPages(alloc_size));
     }
 
-    ~VirtualBuffer() {
+    ~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) {
         FreeMemoryPages(base_ptr, alloc_size);
 
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