add ItemRT.afs decoder

src/AFSArchive.hh

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <stdint.h>
+
+#include <memory>
+#include <phosg/Filesystem.hh>
+#include <phosg/Strings.hh>
+#include <string>
+#include <unordered_map>
+
+class AFSArchive {
+public:
+  AFSArchive(std::shared_ptr<const std::string> data);
+  ~AFSArchive() = default;
+
+  struct Entry {
+    uint64_t offset;
+    uint32_t size;
+  };
+  inline const std::vector<Entry>& all_entries() const {
+    return this->entries;
+  }
+
+  std::pair<const void*, size_t> get(size_t index) const;
+  std::string get_copy(size_t index) const;
+  StringReader get_reader(size_t index) const;
+
+private:
+  std::shared_ptr<const std::string> data;
+  std::vector<Entry> entries;
+};