core: device_manager: Add a simple class to manage device RAM.

src/core/device_memory.cpp

@@ -0,0 +1,50 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+#include "common/assert.h"
+#include "core/core.h"
+#include "core/device_memory.h"
+#include "core/memory.h"
+
+namespace Core {
+
+constexpr u64 DramSize{4ULL * 1024 * 1024 * 1024};
+
+DeviceMemory::DeviceMemory(System& system) : system{system} {
+#ifdef _WIN32
+    base = static_cast<u8*>(
+        VirtualAlloc(nullptr,                                    // System selects address
+                     DramSize,                                   // Size of allocation
+                     MEM_RESERVE | MEM_COMMIT | MEM_WRITE_WATCH, // Allocate reserved pages
+                     PAGE_READWRITE));                           // Protection = no access
+#else
+    physical_memory.resize(DramSize);
+    base = physical_memory.data();
+#endif
+}
+
+DeviceMemory::~DeviceMemory() {
+#ifdef _WIN32
+    ASSERT(VirtualFree(base, DramSize, MEM_RELEASE));
+#endif
+}
+
+PAddr DeviceMemory::GetPhysicalAddr(VAddr addr) {
+    u8* pointer{system.Memory().GetPointer(addr)};
+    ASSERT(pointer);
+    const uintptr_t offset{static_cast<uintptr_t>(pointer - GetPointer(DramMemoryMap::Base))};
+    return DramMemoryMap::Base + offset;
+}
+
+u8* DeviceMemory::GetPointer(PAddr addr) {
+    ASSERT(addr >= DramMemoryMap::Base);
+    ASSERT(addr < DramMemoryMap::Base + DramSize);
+    return base + (addr - DramMemoryMap::Base);
+}
+
+} // namespace Core