10 files changed, 218 insertions, 64 deletions

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index eeceaa655..6ffc612e7 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -155,6 +155,8 @@ add_library(common STATIC
     uuid.cpp
     uuid.h
     vector_math.h
+    virtual_buffer.cpp
+    virtual_buffer.h
     web_result.h
     zstd_compression.cpp
     zstd_compression.h
diff --git a/src/common/alignment.h b/src/common/alignment.h
index cdd4833f8..f8c49e079 100644
--- a/src/common/alignment.h
+++ b/src/common/alignment.h
@@ -38,6 +38,13 @@ constexpr bool IsWordAligned(T value) {
     return (value & 0b11) == 0;
 }
 
+template <typename T>
+constexpr bool IsAligned(T value, std::size_t alignment) {
+    using U = typename std::make_unsigned<T>::type;
+    const U mask = static_cast<U>(alignment - 1);
+    return (value & mask) == 0;
+}
+
 template <typename T, std::size_t Align = 16>
 class AlignmentAllocator {
 public:
diff --git a/src/common/common_funcs.h b/src/common/common_funcs.h
index 052254678..88cf5250a 100644
--- a/src/common/common_funcs.h
+++ b/src/common/common_funcs.h
@@ -55,6 +55,38 @@ __declspec(dllimport) void __stdcall DebugBreak(void);
 // Defined in Misc.cpp.
 std::string GetLastErrorMsg();
 
+#define DECLARE_ENUM_FLAG_OPERATORS(type)                                                          \
+    constexpr type operator|(type a, type b) noexcept {                                            \
+        using T = std::underlying_type_t<type>;                                                    \
+        return static_cast<type>(static_cast<T>(a) | static_cast<T>(b));                           \
+    }                                                                                              \
+    constexpr type operator&(type a, type b) noexcept {                                            \
+        using T = std::underlying_type_t<type>;                                                    \
+        return static_cast<type>(static_cast<T>(a) & static_cast<T>(b));                           \
+    }                                                                                              \
+    constexpr type& operator|=(type& a, type b) noexcept {                                         \
+        using T = std::underlying_type_t<type>;                                                    \
+        a = static_cast<type>(static_cast<T>(a) | static_cast<T>(b));                              \
+        return a;                                                                                  \
+    }                                                                                              \
+    constexpr type& operator&=(type& a, type b) noexcept {                                         \
+        using T = std::underlying_type_t<type>;                                                    \
+        a = static_cast<type>(static_cast<T>(a) & static_cast<T>(b));                              \
+        return a;                                                                                  \
+    }                                                                                              \
+    constexpr type operator~(type key) noexcept {                                                  \
+        using T = std::underlying_type_t<type>;                                                    \
+        return static_cast<type>(~static_cast<T>(key));                                            \
+    }                                                                                              \
+    constexpr bool True(type key) noexcept {                                                       \
+        using T = std::underlying_type_t<type>;                                                    \
+        return static_cast<T>(key) != 0;                                                           \
+    }                                                                                              \
+    constexpr bool False(type key) noexcept {                                                      \
+        using T = std::underlying_type_t<type>;                                                    \
+        return static_cast<T>(key) == 0;                                                           \
+    }
+
 namespace Common {
 
 constexpr u32 MakeMagic(char a, char b, char c, char d) {
diff --git a/src/common/file_util.cpp b/src/common/file_util.cpp
index 35eee0096..45b750e1e 100644
--- a/src/common/file_util.cpp
+++ b/src/common/file_util.cpp
@@ -888,7 +888,14 @@ std::string SanitizePath(std::string_view path_, DirectorySeparator directory_se
     }
 
     std::replace(path.begin(), path.end(), type1, type2);
-    path.erase(std::unique(path.begin(), path.end(),
+
+    auto start = path.begin();
+#ifdef _WIN32
+    // allow network paths which start with a double backslash (e.g. \\server\share)
+    if (start != path.end())
+        ++start;
+#endif
+    path.erase(std::unique(start, path.end(),
                            [type2](char c1, char c2) { return c1 == type2 && c2 == type2; }),
                path.end());
     return std::string(RemoveTrailingSlash(path));
@@ -967,6 +974,34 @@ bool IOFile::Flush() {
     return IsOpen() && 0 == std::fflush(m_file);
 }
 
+std::size_t IOFile::ReadImpl(void* data, std::size_t length, std::size_t data_size) const {
+    if (!IsOpen()) {
+        return std::numeric_limits<std::size_t>::max();
+    }
+
+    if (length == 0) {
+        return 0;
+    }
+
+    DEBUG_ASSERT(data != nullptr);
+
+    return std::fread(data, data_size, length, m_file);
+}
+
+std::size_t IOFile::WriteImpl(const void* data, std::size_t length, std::size_t data_size) {
+    if (!IsOpen()) {
+        return std::numeric_limits<std::size_t>::max();
+    }
+
+    if (length == 0) {
+        return 0;
+    }
+
+    DEBUG_ASSERT(data != nullptr);
+
+    return std::fwrite(data, data_size, length, m_file);
+}
+
 bool IOFile::Resize(u64 size) {
     return IsOpen() && 0 ==
 #ifdef _WIN32
diff --git a/src/common/file_util.h b/src/common/file_util.h
index cde7ddf2d..f7a0c33fa 100644
--- a/src/common/file_util.h
+++ b/src/common/file_util.h
@@ -222,22 +222,15 @@ public:
         static_assert(std::is_trivially_copyable_v<T>,
                       "Given array does not consist of trivially copyable objects");
 
-        if (!IsOpen()) {
-            return std::numeric_limits<std::size_t>::max();
-        }
-
-        return std::fread(data, sizeof(T), length, m_file);
+        return ReadImpl(data, length, sizeof(T));
     }
 
     template <typename T>
     std::size_t WriteArray(const T* data, std::size_t length) {
         static_assert(std::is_trivially_copyable_v<T>,
                       "Given array does not consist of trivially copyable objects");
-        if (!IsOpen()) {
-            return std::numeric_limits<std::size_t>::max();
-        }
 
-        return std::fwrite(data, sizeof(T), length, m_file);
+        return WriteImpl(data, length, sizeof(T));
     }
 
     template <typename T>
@@ -278,6 +271,9 @@ public:
     }
 
 private:
+    std::size_t ReadImpl(void* data, std::size_t length, std::size_t data_size) const;
+    std::size_t WriteImpl(const void* data, std::size_t length, std::size_t data_size);
+
     std::FILE* m_file = nullptr;
 };
 
diff --git a/src/common/page_table.cpp b/src/common/page_table.cpp
index 566b57b62..e5d3090d5 100644
--- a/src/common/page_table.cpp
+++ b/src/common/page_table.cpp
@@ -6,36 +6,20 @@
 
 namespace Common {
 
-PageTable::PageTable(std::size_t page_size_in_bits) : page_size_in_bits{page_size_in_bits} {}
+PageTable::PageTable() = default;
 
 PageTable::~PageTable() = default;
 
-void PageTable::Resize(std::size_t address_space_width_in_bits) {
-    const std::size_t num_page_table_entries = 1ULL
-                                               << (address_space_width_in_bits - page_size_in_bits);
-
+void PageTable::Resize(std::size_t address_space_width_in_bits, std::size_t page_size_in_bits,
+                       bool has_attribute) {
+    const std::size_t num_page_table_entries{1ULL
+                                             << (address_space_width_in_bits - page_size_in_bits)};
     pointers.resize(num_page_table_entries);
-    attributes.resize(num_page_table_entries);
-
-    // The default is a 39-bit address space, which causes an initial 1GB allocation size. If the
-    // vector size is subsequently decreased (via resize), the vector might not automatically
-    // actually reallocate/resize its underlying allocation, which wastes up to ~800 MB for
-    // 36-bit titles. Call shrink_to_fit to reduce capacity to what's actually in use.
-
-    pointers.shrink_to_fit();
-    attributes.shrink_to_fit();
-}
-
-BackingPageTable::BackingPageTable(std::size_t page_size_in_bits) : PageTable{page_size_in_bits} {}
-
-BackingPageTable::~BackingPageTable() = default;
-
-void BackingPageTable::Resize(std::size_t address_space_width_in_bits) {
-    PageTable::Resize(address_space_width_in_bits);
-    const std::size_t num_page_table_entries = 1ULL
-                                               << (address_space_width_in_bits - page_size_in_bits);
     backing_addr.resize(num_page_table_entries);
-    backing_addr.shrink_to_fit();
+
+    if (has_attribute) {
+        attributes.resize(num_page_table_entries);
+    }
 }
 
 } // namespace Common
diff --git a/src/common/page_table.h b/src/common/page_table.h
index dbc272ab7..1e8bd3187 100644
--- a/src/common/page_table.h
+++ b/src/common/page_table.h
@@ -5,9 +5,12 @@
 #pragma once
 
 #include <vector>
+
 #include <boost/icl/interval_map.hpp>
+
 #include "common/common_types.h"
 #include "common/memory_hook.h"
+#include "common/virtual_buffer.h"
 
 namespace Common {
 
@@ -47,7 +50,7 @@ struct SpecialRegion {
  * mimics the way a real CPU page table works.
  */
 struct PageTable {
-    explicit PageTable(std::size_t page_size_in_bits);
+    PageTable();
     ~PageTable();
 
     /**
@@ -56,40 +59,18 @@ struct PageTable {
      *
      * @param address_space_width_in_bits The address size width in bits.
      */
-    void Resize(std::size_t address_space_width_in_bits);
+    void Resize(std::size_t address_space_width_in_bits, std::size_t page_size_in_bits,
+                bool has_attribute);
 
     /**
      * Vector of memory pointers backing each page. An entry can only be non-null if the
      * corresponding entry in the `attributes` vector is of type `Memory`.
      */
-    std::vector<u8*> pointers;
-
-    /**
-     * Contains MMIO handlers that back memory regions whose entries in the `attribute` vector is
-     * of type `Special`.
-     */
-    boost::icl::interval_map<u64, std::set<SpecialRegion>> special_regions;
-
-    /**
-     * Vector of fine grained page attributes. If it is set to any value other than `Memory`, then
-     * the corresponding entry in `pointers` MUST be set to null.
-     */
-    std::vector<PageType> attributes;
-
-    const std::size_t page_size_in_bits{};
-};
-
-/**
- * A more advanced Page Table with the ability to save a backing address when using it
- * depends on another MMU.
- */
-struct BackingPageTable : PageTable {
-    explicit BackingPageTable(std::size_t page_size_in_bits);
-    ~BackingPageTable();
+    VirtualBuffer<u8*> pointers;
 
-    void Resize(std::size_t address_space_width_in_bits);
+    VirtualBuffer<u64> backing_addr;
 
-    std::vector<u64> backing_addr;
+    VirtualBuffer<PageType> attributes;
 };
 
 } // namespace Common
diff --git a/src/common/scope_exit.h b/src/common/scope_exit.h
index 1176a72b1..68ef5f197 100644
--- a/src/common/scope_exit.h
+++ b/src/common/scope_exit.h
@@ -12,10 +12,17 @@ template <typename Func>
 struct ScopeExitHelper {
     explicit ScopeExitHelper(Func&& func) : func(std::move(func)) {}
     ~ScopeExitHelper() {
-        func();
+        if (active) {
+            func();
+        }
+    }
+
+    void Cancel() {
+        active = false;
     }
 
     Func func;
+    bool active{true};
 };
 
 template <typename Func>
diff --git a/src/common/virtual_buffer.cpp b/src/common/virtual_buffer.cpp
new file mode 100644
index 000000000..b426f4747
--- /dev/null
+++ b/src/common/virtual_buffer.cpp
@@ -0,0 +1,52 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#if defined __APPLE__ || defined __FreeBSD__ || defined __OpenBSD__
+#include <sys/sysctl.h>
+#elif defined __HAIKU__
+#include <OS.h>
+#else
+#include <sys/sysinfo.h>
+#endif
+#endif
+
+#include "common/assert.h"
+#include "common/virtual_buffer.h"
+
+namespace Common {
+
+void* AllocateMemoryPages(std::size_t size) {
+#ifdef _WIN32
+    void* base{VirtualAlloc(nullptr, size, MEM_COMMIT, PAGE_READWRITE)};
+#else
+    void* base{mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0)};
+
+    if (base == MAP_FAILED) {
+        base = nullptr;
+    }
+#endif
+
+    ASSERT(base);
+
+    return base;
+}
+
+void FreeMemoryPages(void* base, std::size_t size) {
+    if (!base) {
+        return;
+    }
+#ifdef _WIN32
+    ASSERT(VirtualFree(base, 0, MEM_RELEASE));
+#else
+    ASSERT(munmap(base, size) == 0);
+#endif
+}
+
+} // namespace Common
diff --git a/src/common/virtual_buffer.h b/src/common/virtual_buffer.h
new file mode 100644
index 000000000..da064e59e
--- /dev/null
+++ b/src/common/virtual_buffer.h
@@ -0,0 +1,58 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_funcs.h"
+
+namespace Common {
+
+void* AllocateMemoryPages(std::size_t size);
+void FreeMemoryPages(void* base, std::size_t size);
+
+template <typename T>
+class VirtualBuffer final : NonCopyable {
+public:
+    constexpr VirtualBuffer() = default;
+    explicit VirtualBuffer(std::size_t count) : alloc_size{count * sizeof(T)} {
+        base_ptr = reinterpret_cast<T*>(AllocateMemoryPages(alloc_size));
+    }
+
+    ~VirtualBuffer() {
+        FreeMemoryPages(base_ptr, alloc_size);
+    }
+
+    void resize(std::size_t count) {
+        FreeMemoryPages(base_ptr, alloc_size);
+
+        alloc_size = count * sizeof(T);
+        base_ptr = reinterpret_cast<T*>(AllocateMemoryPages(alloc_size));
+    }
+
+    constexpr const T& operator[](std::size_t index) const {
+        return base_ptr[index];
+    }
+
+    constexpr T& operator[](std::size_t index) {
+        return base_ptr[index];
+    }
+
+    constexpr T* data() {
+        return base_ptr;
+    }
+
+    constexpr const T* data() const {
+        return base_ptr;
+    }
+
+    constexpr std::size_t size() const {
+        return alloc_size / sizeof(T);
+    }
+
+private:
+    std::size_t alloc_size{};
+    T* base_ptr{};
+};
+
+} // namespace Common