diff --git a/src/framework/filesystem.cpp b/src/framework/filesystem.cpp
new file mode 100644
index 0000000..8994761
--- /dev/null
+++ b/src/framework/filesystem.cpp
@@ -0,0 +1,273 @@
+
+#include "filesystem.h"
+#include "zipreader.h"
+#include "file.h"
+#include <map>
+#include <stdexcept>
+
+FFileSystem fileSystem;
+
+/////////////////////////////////////////////////////////////////////////////
+
+class ZipFileSystemSource : public IFileSystemSource
+{
+public:
+	ZipFileSystemSource(const FString& filename)
+	{
+		zip = ZipReader::open(filename.GetChars());
+	}
+
+	int GetLumpCount() override
+	{
+		return zip->get_num_files();
+	}
+	
+	int CheckNumForFullName(const FString& fullname) override
+	{
+		return zip->locate_file(fullname.GetChars());
+	}
+
+	int FileLength(int lump) override
+	{
+		uint64_t size = zip->get_uncompressed_size(lump);
+		// For safety. The filesystem API clearly wasn't designed to handle large files.
+		if (size >= 0x7fffffff) throw std::runtime_error("File is too big");
+		return (int)size;
+	}
+
+	FileData ReadFile(int lump) override
+	{
+		FileData data;
+		data.Buffer = zip->read_all_bytes(lump);
+		return data;
+	}
+
+	const char* GetFileFullName(int lump, bool returnshort) override
+	{
+		static std::string tempstring;
+		tempstring = zip->get_filename(lump);
+		return tempstring.c_str();
+	}
+
+	std::unique_ptr<ZipReader> zip;
+};
+
+/////////////////////////////////////////////////////////////////////////////
+
+class FolderFileSystemSource : public IFileSystemSource
+{
+public:
+	FolderFileSystemSource(const FString& foldername)
+	{
+		ScanFolder(foldername.GetChars());
+	}
+
+	int GetLumpCount() override
+	{
+		return (int)Filenames.size();
+	}
+
+	int CheckNumForFullName(const FString& fullname) override
+	{
+		auto it = FilenameKeyToIndex.find(fullname.GetChars());
+		if (it == FilenameKeyToIndex.end())
+			return -1;
+		return (int)it->second;
+	}
+
+	int FileLength(int lump) override
+	{
+		int64_t size = File::open_existing(Filenames[lump])->size();
+		// For safety. The filesystem API clearly wasn't designed to handle large files.
+		if (size >= 0x7fffffff) throw std::runtime_error("File is too big");
+		return (int)size;
+	}
+
+	FileData ReadFile(int lump) override
+	{
+		FileData data;
+		data.Buffer = File::read_all_bytes(Filenames[lump]);
+		return data;
+	}
+
+	const char* GetFileFullName(int lump, bool returnshort) override
+	{
+		return Filenames[lump].c_str();
+	}
+
+	void ScanFolder(const std::string& foldername, int depth = 0)
+	{
+		for (const std::string& filename : Directory::files(foldername))
+		{
+			std::string fullname = FilePath::combine(foldername, filename);
+			FilenameKeyToIndex[fullname] = Filenames.size();
+			Filenames.push_back(fullname);
+		}
+
+		if (depth < 16)
+		{
+			for (const std::string& subfolder : Directory::folders(foldername))
+			{
+				ScanFolder(FilePath::combine(foldername, subfolder), depth + 1);
+			}
+		}
+	}
+
+	std::vector<std::string> Filenames;
+	std::map<std::string, size_t> FilenameKeyToIndex;
+};
+
+/////////////////////////////////////////////////////////////////////////////
+
+class WadFileEntry
+{
+public:
+	uint32_t offset = 0;
+	uint32_t size = 0;
+	std::string name;
+	void *data = nullptr;
+};
+
+class WadFileSystemSource : public IFileSystemSource
+{
+public:
+	WadFileSystemSource(const FString& filename)
+	{
+		file = File::open_existing(filename.GetChars());
+
+		char magic[4];
+		file->read(magic, 4);
+		pwad = memcmp(magic, "PWAD", 4) == 0;
+		iwad = memcmp(magic, "IWAD", 4) == 0;
+		if (!pwad && !iwad)
+			throw std::runtime_error("Not a valid WAD file");
+
+		uint32_t num_entries = file->read_uint32();
+		uint32_t directory_offset = file->read_uint32();
+		file->seek(directory_offset);
+		for (uint32_t i = 0; i < num_entries; i++)
+		{
+			WadFileEntry entry;
+			entry.offset = file->read_uint32();
+			entry.size = file->read_uint32();
+
+			char name[9];
+			name[8] = 0;
+			file->read(name, 8);
+			entry.name = name;
+
+			FilenameKeyToIndex[entry.name] = entries.size();
+			entries.push_back(entry);
+		}
+	}
+
+	int GetLumpCount() override
+	{
+		return (int)entries.size();
+	}
+
+	int CheckNumForFullName(const FString& fullname) override
+	{
+		auto it = FilenameKeyToIndex.find(fullname.GetChars());
+		if (it == FilenameKeyToIndex.end())
+			return -1;
+		return (int)it->second;
+	}
+
+	int FileLength(int lump) override
+	{
+		return entries[lump].size;
+	}
+
+	FileData ReadFile(int lump) override
+	{
+		FileData data;
+		data.Buffer.resize(entries[lump].size);
+		file->seek(entries[lump].offset);
+		file->read(data.Buffer.data(), data.Buffer.size());
+		return data;
+	}
+
+	const char* GetFileFullName(int lump, bool returnshort) override
+	{
+		return entries[lump].name.c_str();
+	}
+
+	std::shared_ptr<File> file;
+	bool pwad = false;
+	bool iwad = false;
+	std::vector<WadFileEntry> entries;
+	std::map<std::string, size_t> FilenameKeyToIndex;
+};
+
+/////////////////////////////////////////////////////////////////////////////
+
+void FFileSystem::AddZipSource(const FString& filename)
+{
+	Sources.push_back(std::make_unique<ZipFileSystemSource>(filename));
+}
+
+void FFileSystem::AddFolderSource(const FString& foldername)
+{
+	Sources.push_back(std::make_unique<FolderFileSystemSource>(foldername));
+}
+
+void FFileSystem::AddWadSource(const FString& filename)
+{
+	Sources.push_back(std::make_unique<WadFileSystemSource>(filename));
+}
+
+int FFileSystem::CheckNumForFullName(const FString& fullname)
+{
+	int pos = 0;
+	for (auto& source : Sources)
+	{
+		int index = source->CheckNumForFullName(fullname);
+		if (index != -1)
+			return pos + index;
+		pos += source->GetLumpCount();
+	}
+	return -1;
+}
+
+int FFileSystem::FileLength(int lump)
+{
+	int pos = 0;
+	for (auto& source : Sources)
+	{
+		if (lump - pos < source->GetLumpCount())
+		{
+			return source->FileLength(lump - pos);
+		}
+		pos += source->GetLumpCount();
+	}
+	return 0;
+}
+
+FileData FFileSystem::ReadFile(int lump)
+{
+	int pos = 0;
+	for (auto& source : Sources)
+	{
+		if (lump - pos < source->GetLumpCount())
+		{
+			return source->ReadFile(lump - pos);
+		}
+		pos += source->GetLumpCount();
+	}
+	return {};
+}
+
+const char* FFileSystem::GetFileFullName(int lump, bool returnshort) const
+{
+	int pos = 0;
+	for (auto& source : Sources)
+	{
+		if (lump - pos < source->GetLumpCount())
+		{
+			return source->GetFileFullName(lump - pos, returnshort);
+		}
+		pos += source->GetLumpCount();
+	}
+	return {};
+}
diff --git a/src/framework/filesystem.h b/src/framework/filesystem.h
new file mode 100644
index 0000000..34c1707
--- /dev/null
+++ b/src/framework/filesystem.h
@@ -0,0 +1,42 @@
+#pragma once
+
+#include "framework/tarray.h"
+#include "framework/templates.h"
+#include "framework/zstring.h"
+#include <memory>
+#include <vector>
+
+struct FileData
+{
+	char* GetMem() { return (char*)Buffer.data(); }
+	std::vector<uint8_t> Buffer;
+};
+
+class IFileSystemSource
+{
+public:
+	virtual ~IFileSystemSource() = default;
+	virtual int GetLumpCount() = 0;
+	virtual int CheckNumForFullName(const FString& fullname) = 0;
+	virtual int FileLength(int lump) = 0;
+	virtual FileData ReadFile(int lump) = 0;
+	virtual const char* GetFileFullName(int lump, bool returnshort) = 0;
+};
+
+class FFileSystem
+{
+public:
+	void AddZipSource(const FString& filename);
+	void AddFolderSource(const FString& foldername);
+	void AddWadSource(const FString& filename);
+
+	int CheckNumForFullName(const FString& fullname);
+	int FileLength(int lump);
+	FileData ReadFile(int lump);
+	const char* GetFileFullName(int lump, bool returnshort = true) const;
+
+private:
+	std::vector<std::unique_ptr<IFileSystemSource>> Sources;
+};
+
+extern FFileSystem fileSystem;