Bus: 16KB page compatibility for mmap fastmem

src/common/memmap.h

@@ -0,0 +1,78 @@
+// SPDX-FileCopyrightText: 2019-2023 Connor McLaughlin <stenzek@gmail.com>
+// SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)
+
+#pragma once
+
+#include "types.h"
+
+#include <map>
+#include <string>
+
+#ifdef _WIN32
+
+// eww :/ but better than including windows.h
+enum class PageProtect : u32
+{
+  NoAccess = 0x01,         // PAGE_NOACCESS
+  ReadOnly = 0x02,         // PAGE_READONLY
+  ReadWrite = 0x04,        // PAGE_READWRITE
+  ReadExecute = 0x20,      // PAGE_EXECUTE_READ
+  ReadWriteExecute = 0x40, // PAGE_EXECUTE_READWRITE
+};
+#else
+
+#include <sys/mman.h>
+
+enum class PageProtect : u32
+{
+  NoAccess = PROT_NONE,
+  ReadOnly = PROT_READ,
+  ReadWrite = PROT_READ | PROT_WRITE,
+  ReadExecute = PROT_READ | PROT_EXEC,
+  ReadWriteExecute = PROT_READ | PROT_WRITE | PROT_EXEC,
+};
+
+#endif
+
+namespace MemMap {
+std::string GetFileMappingName(const char* prefix);
+void* CreateSharedMemory(const char* name, size_t size);
+void DestroySharedMemory(void* ptr);
+void* MapSharedMemory(void* handle, size_t offset, void* baseaddr, size_t size, PageProtect mode);
+void UnmapSharedMemory(void* baseaddr, size_t size);
+bool MemProtect(void* baseaddr, size_t size, PageProtect mode);
+} // namespace MemMap
+
+class SharedMemoryMappingArea
+{
+public:
+  SharedMemoryMappingArea();
+  ~SharedMemoryMappingArea();
+
+  ALWAYS_INLINE size_t GetSize() const { return m_size; }
+  ALWAYS_INLINE size_t GetNumPages() const { return m_num_pages; }
+
+  ALWAYS_INLINE u8* BasePointer() const { return m_base_ptr; }
+  ALWAYS_INLINE u8* OffsetPointer(size_t offset) const { return m_base_ptr + offset; }
+  ALWAYS_INLINE u8* PagePointer(size_t page) const { return m_base_ptr + HOST_PAGE_SIZE * page; }
+
+  bool Create(size_t size);
+  void Destroy();
+
+  u8* Map(void* file_handle, size_t file_offset, void* map_base, size_t map_size, PageProtect mode);
+  bool Unmap(void* map_base, size_t map_size);
+
+private:
+  u8* m_base_ptr = nullptr;
+  size_t m_size = 0;
+  size_t m_num_pages = 0;
+  size_t m_num_mappings = 0;
+
+#ifdef _WIN32
+  using PlaceholderMap = std::map<size_t, size_t>;
+
+  PlaceholderMap::iterator FindPlaceholder(size_t page);
+
+  PlaceholderMap m_placeholder_ranges;
+#endif
+};