diff --git a/bin/CMakeLists.txt b/bin/CMakeLists.txt
index c4c7385..ba049b7 100644
--- a/bin/CMakeLists.txt
+++ b/bin/CMakeLists.txt
@@ -77,6 +77,7 @@ target_link_libraries(mpw MPW_LIB)
 target_link_libraries(mpw MPLITE_LIB)
 target_link_libraries(mpw NATIVE_LIB)
 target_link_libraries(mpw MACOS_LIB)
+target_link_libraries(mpw CXX_LIB)
 set_target_properties(mpw PROPERTIES LINK_FLAGS "-ledit")
 
 
diff --git a/cxx/CMakeLists.txt b/cxx/CMakeLists.txt
new file mode 100644
index 0000000..6adab7e
--- /dev/null
+++ b/cxx/CMakeLists.txt
@@ -0,0 +1,4 @@
+
+set(CXX_SRC mapped_file.cpp)
+
+add_library(CXX_LIB ${CXX_SRC})
diff --git a/cxx/mapped_file.cpp b/cxx/mapped_file.cpp
new file mode 100644
index 0000000..fee94a3
--- /dev/null
+++ b/cxx/mapped_file.cpp
@@ -0,0 +1,377 @@
+#include "mapped_file.h"
+#include <memory>
+#include <functional>
+#include <system_error>
+
+#include "unique_resource.h"
+
+namespace {
+	class defer {
+	public:
+		typedef std::function<void()> FX;
+		defer() = default;
+
+		defer(FX fx) : _fx(fx) {}
+		defer(const defer &) = delete;
+		defer(defer &&) = default;
+		defer & operator=(const defer &) = delete;
+		defer & operator=(defer &&) = default;
+
+		void cancel() { _fx = nullptr;  }
+		~defer() { if (_fx) _fx(); }
+	private:
+		FX _fx;
+	};
+
+	void throw_error(int error) {
+		throw std::system_error(error, std::system_category());
+	}
+
+
+	void throw_error(int error, const std::string &what) {
+		throw std::system_error(error, std::system_category(), what);
+	}
+
+
+
+}
+
+#ifdef _WIN32
+#include <windows.h>
+
+namespace {
+
+	void throw_error() {
+		throw_error(GetLastError());
+	}
+
+	void throw_error(const std::string &what) {
+		throw_error(GetLastError(), what);
+	}
+
+}
+
+void mapped_file_base::close() {
+	if (is_open()) {
+
+		UnmapViewOfFile(_data);
+		CloseHandle(_map_handle);
+		CloseHandle(_file_handle);
+		reset();
+	}
+}
+
+void mapped_file_base::open(const path_type& p, mapmode flags, size_t length, size_t offset) {
+
+
+	HANDLE fh;
+	HANDLE mh;
+
+	// length of 0 in CreateFileMapping / MapViewOfFile
+	// means map the entire file.
+
+	if (is_open()) {
+		throw std::runtime_error("mapped_file_base::open - file already open");
+	}
+
+	fh = CreateFile(p.c_str(), 
+		flags == readonly ? GENERIC_READ : GENERIC_READ | GENERIC_WRITE,
+		FILE_SHARE_READ, 
+		nullptr,
+		OPEN_EXISTING, 
+		flags == readonly ? FILE_ATTRIBUTE_READONLY : FILE_ATTRIBUTE_NORMAL,
+		nullptr
+	);
+	if (fh == INVALID_HANDLE_VALUE) {
+		throw_error();
+	}
+
+	auto fh_close = make_unique_resource(fh, CloseHandle);
+
+
+	if (length == -1) {
+		LARGE_INTEGER file_size;
+		GetFileSizeEx(fh, &file_size);
+		length = file_size.QuadPart;
+	}
+
+	if (length == 0) return;
+
+	DWORD protect = 0;
+	DWORD access = 0;
+	switch (flags) {
+	case readonly:
+		protect = PAGE_READONLY;
+		access = FILE_MAP_READ;
+		break;
+	case readwrite:
+		protect = PAGE_READWRITE;
+		access = FILE_MAP_WRITE;
+		break;
+	case priv:
+		protect = PAGE_WRITECOPY;
+		access = FILE_MAP_WRITE;
+		break;
+	}
+
+	mh = CreateFileMapping(fh, nullptr, protect, 0, 0, 0);
+	if (mh == INVALID_HANDLE_VALUE) {
+		throw_error();
+	}
+
+	auto mh_close = make_unique_resource(mh, CloseHandle);
+
+
+	_data = MapViewOfFileEx(mh, 
+		access, 
+		(DWORD)(offset >> 32), 
+		(DWORD)offset, 
+		length, 
+		nullptr);
+	if (!_data) {
+		throw_error();
+	}
+
+
+	_file_handle = fh_close.release();
+	_map_handle = mh_close.release();
+	_size = length;
+	_flags = flags;
+}
+
+
+void mapped_file_base::create(const path_type& p, size_t length) {
+
+	const size_t offset = 0;
+
+	HANDLE fh;
+	HANDLE mh;
+	LARGE_INTEGER file_size;
+
+	const DWORD protect = PAGE_READWRITE;
+	const DWORD access = FILE_MAP_WRITE;
+
+
+	if (is_open()) {
+		throw std::runtime_error("mapped_file_base::create - file already open");
+	}
+
+
+	fh = CreateFile(p.c_str(), 
+		GENERIC_READ | GENERIC_WRITE,
+		FILE_SHARE_READ, 
+		nullptr,
+		CREATE_ALWAYS, 
+		FILE_ATTRIBUTE_NORMAL,
+		nullptr
+	);
+	if (fh == INVALID_HANDLE_VALUE) {
+		throw_error();
+	}
+
+	auto fh_close = make_unique_resource(fh, CloseHandle);
+
+
+	file_size.QuadPart = length;
+	if (!SetFilePointerEx(fh, file_size, nullptr, FILE_BEGIN));
+	if (!SetEndOfFile(fh)) throw_error();
+
+	mh = CreateFileMapping(fh, nullptr, protect, 0, 0, 0);
+	if (mh == INVALID_HANDLE_VALUE) {
+		throw_error();
+	}
+
+	auto mh_close = make_unique_resource(mh, CloseHandle);
+
+	_data = MapViewOfFileEx(mh, 
+		access, 
+		(DWORD)(offset >> 32), 
+		(DWORD)offset, 
+		length, 
+		nullptr);
+
+	if (!_data) {
+		throw_error();
+	}
+
+	_file_handle = fh_close.release();
+	_map_handle = mh_close.release();
+
+	_size = length;
+	_flags = readwrite;
+}
+
+
+
+#else
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <cerrno>
+
+namespace {
+
+	void throw_error() {
+		throw_error(errno);
+	}
+
+	void throw_error(const std::string &what) {
+		throw_error(errno, what);
+	}
+
+}
+
+void mapped_file_base::close() {
+	if (is_open()) {
+		::munmap(_data, _size);
+		::close(_fd);
+		reset();
+	}
+}
+
+
+void mapped_file_base::open(const path_type& p, mapmode flags, size_t length, size_t offset) {
+
+	int fd;
+
+	int oflags = 0;
+
+	if (is_open()) {
+		throw std::runtime_error("mapped_file_base::open - file already open");
+	}
+
+	switch (flags) {
+	case readonly:
+		oflags = O_RDONLY;
+		break;
+	default:
+		oflags = O_RDWR;
+		break;
+	}
+
+	fd = ::open(p.c_str(), oflags);
+	if (fd < 0) {
+		throw_error(errno);
+	}
+
+	//defer([fd](){::close(fd); });
+	auto close_fd = make_unique_resource(fd, ::close);
+
+
+
+	if (length == -1) {
+		struct stat st;
+
+		if (::fstat(fd, &st) < 0) {
+			throw_error(errno);
+		}
+		length = st.st_size;
+	}
+
+	if (length == 0) return;
+
+	_data = ::mmap(0, length, 
+		flags == readonly ? PROT_READ : PROT_READ | PROT_WRITE, 
+		flags == priv ? MAP_PRIVATE : MAP_SHARED, 
+		fd, offset);
+
+	if (_data == MAP_FAILED) {
+		_data = nullptr;
+		throw_error(errno);
+	}
+
+	_fd = close_fd.release();
+	_size = length;
+	_flags = flags;
+}
+
+void mapped_file_base::create(const path_type& p, size_t length) {
+
+	int fd;
+	const size_t offset = 0;
+
+	if (is_open()) {
+		throw std::runtime_error("mapped_file_base::create - file already open");
+	}
+
+
+
+	fd = ::open(p.c_str(), O_RDWR | O_CREAT | O_TRUNC);
+	if (fd < 0) {
+		throw_error(errno);
+	}
+
+	//defer([fd](){::close(fd); });
+
+	auto close_fd = make_unique_resource(fd, ::close);
+
+
+	if (::ftruncate(fd, length) < 0) {
+		throw_error(errno);
+	}
+
+
+	_data = ::mmap(0, length, 
+		PROT_READ | PROT_WRITE, 
+		MAP_SHARED, 
+		fd, offset);
+
+	if (_data == MAP_FAILED) {
+		_data = nullptr;
+		throw_error(errno);
+	}
+
+	_fd = close_fd.release();
+	_size = length;
+	_flags = readwrite;
+}
+
+
+
+#endif
+
+
+void mapped_file_base::reset() {
+	_data = nullptr;
+	_size = 0;
+	_flags = readonly;
+#ifdef _WIN32
+	_file_handle = nullptr;
+	_map_handle = nullptr;
+#else
+	_fd = -1;
+#endif
+}
+
+void mapped_file_base::swap(mapped_file_base &rhs)
+{
+	if (std::addressof(rhs) != this) {
+		std::swap(_data, rhs._data);
+		std::swap(_size, rhs._size);
+		std::swap(_flags, rhs._flags);
+#ifdef _WIN32
+		std::swap(_file_handle, rhs._file_handle);
+		std::swap(_map_handle, rhs._map_handle);
+#else
+		std::swap(_fd, rhs._fd);
+#endif
+	}
+}
+
+mapped_file::mapped_file(mapped_file &&rhs) : mapped_file() {
+	swap(rhs);
+	//rhs.reset();
+}
+
+mapped_file& mapped_file::operator=(mapped_file &&rhs) {
+	if (std::addressof(rhs) == this) return *this;
+
+	swap(rhs);
+	rhs.close();
+	//rhs.reset();
+	return *this;
+}
+
+
diff --git a/cxx/mapped_file.h b/cxx/mapped_file.h
new file mode 100644
index 0000000..22da160
--- /dev/null
+++ b/cxx/mapped_file.h
@@ -0,0 +1,143 @@
+#ifndef __mapped_file_h__
+#define __mapped_file_h__
+
+#ifdef HAVE_TSFS
+#include <filesystem>
+#else
+#include <string>
+#endif
+
+#include <cstddef>
+
+class mapped_file_base {
+public:
+
+#ifdef HAVE_TSFS
+	typedef std::filesystem::path path_type ;
+#else
+	typedef std::string path_type ;
+#endif
+
+	enum mapmode { readonly, readwrite, priv };
+
+	void close();
+
+	bool is_open() const {
+		return _data != nullptr;
+	}
+
+	size_t size() const {
+		return _size;
+	}
+
+	operator bool() const { return is_open(); }
+	bool operator !() const { return !is_open(); }
+
+	~mapped_file_base() { close(); }
+
+protected:
+
+	void swap(mapped_file_base &rhs);
+
+	void open(const path_type& p, mapmode flags, size_t length, size_t offset);
+	void create(const path_type &p, size_t new_size); // always creates readwrite.
+	void reset();
+
+
+	size_t _size = 0;
+	void *_data = nullptr;
+	mapmode _flags = readonly;
+
+#ifdef _WIN32
+	void *_file_handle = nullptr;
+	void *_map_handle = nullptr;
+#else
+	int _fd = -1;
+#endif
+};
+
+
+
+class mapped_file : public mapped_file_base {
+
+	typedef mapped_file_base base;
+
+public:
+
+	typedef unsigned char value_type;
+
+	typedef value_type *iterator;
+	typedef const value_type *const_iterator;
+
+	typedef value_type &reference ;
+	typedef const value_type &const_reference;
+
+
+	mapped_file() = default;
+	mapped_file(const path_type& p, mapmode flags = readonly, size_t length = -1, size_t offset = 0) {
+		open(p, flags, length, offset);
+	}
+
+	mapped_file(mapped_file &&);
+	mapped_file(const mapped_file &) = delete;
+
+	mapped_file &operator=(mapped_file &&);
+	mapped_file &operator=(const mapped_file &) = delete;
+
+
+	void open(const path_type& p, mapmode flags, size_t length = -1, size_t offset = 0) {
+		base::open(p, flags, length, offset);
+	}
+
+
+	const value_type *data() const {
+		return (const value_type *)_data;
+	}
+
+	value_type *data() {
+		return _flags == readonly ? (value_type *)nullptr : (value_type *)_data;
+	}
+
+	const_iterator cbegin() const {
+		return data();
+	}
+
+	const_iterator cend() const {
+		return data() + size();
+	}
+
+	const_iterator begin() const {
+		return cbegin();
+	}
+	
+	const_iterator end() const {
+		return cend();
+	}
+
+
+	iterator begin() {
+		return _flags == readonly ? (iterator)nullptr : (iterator)_data;
+	}
+
+	iterator end() {
+		return _flags == readonly ? (iterator)nullptr : (iterator)_data + size();
+	}
+
+	mapmode flags() const {
+		return _flags;
+	}
+	
+	void swap(mapped_file &rhs) {
+		base::swap(rhs);
+	}
+
+};
+
+namespace std {
+	template<class T>
+	void swap(mapped_file &a, mapped_file &b) {
+		a.swap(b);
+	}
+}
+
+#endif
diff --git a/cxx/unique_resource.h b/cxx/unique_resource.h
new file mode 100644
index 0000000..9ec9de0
--- /dev/null
+++ b/cxx/unique_resource.h
@@ -0,0 +1,95 @@
+#ifndef __unique_resource_h__
+#define __unique_resource_h__
+
+#include <utility>
+
+template <class T, class D>
+class unique_resource {
+public:
+	typedef T element_type;
+	typedef D deleter_type;
+
+	unique_resource() = default;
+	unique_resource(const unique_resource &) = delete;
+	unique_resource(unique_resource &&rhs) {
+		swap(rhs);
+	}
+
+	unique_resource(T t, D d): _pair(t,d), _active(true)
+	{}
+
+	~unique_resource() {
+		reset();
+	}
+
+	unique_resource &operator=(const unique_resource &) = delete;
+	unique_resource &operator=(unique_resource &&rhs) {
+		if (this != std::addressof(rhs)) {
+			reset();
+			swap(rhs);
+		}
+		return *this;
+	}
+
+	void swap(unique_resource & rhs) {
+		if (this != std::addressof(rhs)) {
+			std::swap(_active, rhs._active);
+			std::swap(_pair, rhs._pair);
+		}
+	}
+
+	void reset(T t) {
+		reset();
+		_active = true;
+		_pair.first = t;
+	}
+
+	void reset(T t, D d) {
+		reset();
+		_active = true;
+		_pair = std::make_pair(t, d);
+	}
+
+	void reset() {
+		if (_active) {
+			(*_pair.second)(_pair.first);
+			_active = false;
+		}
+	}
+
+	T release() {
+		_active = false;
+		return _pair.first;;
+	}
+
+	T get() {
+		return _pair.first;
+	}
+
+	operator bool() const {
+		return _active; 
+	}
+
+	D& get_deleter() {
+		return _pair.second;
+	}
+
+	const D& get_deleter() const {
+		return _pair.second;
+	}
+
+
+private:
+	std::pair<T, D> _pair;
+	bool _active = false;
+};
+
+#define MAKE_UNIQUE_RESOURCE(T, D) \
+	unique_resource<decltype(T), decltype(D) *>(T, D)
+
+template<class T, class D>
+unique_resource<T, D> make_unique_resource(T t, D d) {
+	return unique_resource<T, D>(t, d);
+}
+
+#endif