From b617874724c461cba270a00c0f8e67fc4a6d553a Mon Sep 17 00:00:00 2001
From: Fernando Sahmkow <fsahmkow27@gmail.com>
Date: Wed, 10 Nov 2021 17:37:17 +0100
Subject: Common: implement MultiLevelPageTable.

---
 src/common/multi_level_page_table.inc | 83 +++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 src/common/multi_level_page_table.inc

(limited to 'src/common/multi_level_page_table.inc')

diff --git a/src/common/multi_level_page_table.inc b/src/common/multi_level_page_table.inc
new file mode 100644
index 000000000..a75e61f9d
--- /dev/null
+++ b/src/common/multi_level_page_table.inc
@@ -0,0 +1,83 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <sys/mman.h>
+#endif
+
+#include "common/assert.h"
+#include "common/multi_level_page_table.h"
+
+namespace Common {
+
+template <typename BaseAddr>
+MultiLevelPageTable<BaseAddr>::MultiLevelPageTable(std::size_t address_space_bits_,
+                                                   std::size_t first_level_bits_,
+                                                   std::size_t page_bits_)
+    : address_space_bits{address_space_bits_},
+      first_level_bits{first_level_bits_}, page_bits{page_bits_} {
+    first_level_shift = address_space_bits - first_level_bits;
+    first_level_chunk_size = 1ULL << (first_level_shift - page_bits);
+    alloc_size = (1ULL << (address_space_bits - page_bits)) * sizeof(BaseAddr);
+    std::size_t first_level_size = 1ULL << first_level_bits;
+    first_level_map.resize(first_level_size, nullptr);
+#ifdef _WIN32
+    void* base{VirtualAlloc(nullptr, alloc_size, MEM_RESERVE, PAGE_READWRITE)};
+#else
+    void* base{mmap(nullptr, alloc_size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)};
+
+    if (base == MAP_FAILED) {
+        base = nullptr;
+    }
+#endif
+
+    ASSERT(base);
+    base_ptr = reinterpret_cast<BaseAddr*>(base);
+}
+
+template <typename BaseAddr>
+MultiLevelPageTable<BaseAddr>::~MultiLevelPageTable() noexcept {
+    if (!base_ptr) {
+        return;
+    }
+#ifdef _WIN32
+    ASSERT(VirtualFree(base_ptr, 0, MEM_RELEASE));
+#else
+    ASSERT(munmap(base_ptr, alloc_size) == 0);
+#endif
+}
+
+template <typename BaseAddr>
+void MultiLevelPageTable<BaseAddr>::ReserveRange(u64 start, std::size_t size) {
+    const u64 new_start = start >> first_level_shift;
+    const u64 new_end =
+        (start + size + (first_level_chunk_size << page_bits) - 1) >> first_level_shift;
+    for (u64 i = new_start; i <= new_end; i++) {
+        if (!first_level_map[i]) {
+            AllocateLevel(i);
+        }
+    }
+}
+
+template <typename BaseAddr>
+void MultiLevelPageTable<BaseAddr>::AllocateLevel(u64 level) {
+    void* ptr = reinterpret_cast<char*>(base_ptr) + level * first_level_chunk_size;
+#ifdef _WIN32
+    void* base{VirtualAlloc(ptr, first_level_chunk_size, MEM_COMMIT, PAGE_READWRITE)};
+#else
+    void* base{mmap(ptr, first_level_chunk_size, PROT_READ | PROT_WRITE,
+                    MAP_ANONYMOUS | MAP_PRIVATE, -1, 0)};
+
+    if (base == MAP_FAILED) {
+        base = nullptr;
+    }
+#endif
+    ASSERT(base);
+
+    first_level_map[level] = base;
+}
+
+} // namespace Common
-- 
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