implemented rfile reading

simulator_SIC_XE/include/string_reader.h

@@ -0,0 +1,17 @@
+#pragma once
+#include "reader.h"
+#include <string>
+#include <sstream>
+
+class StringReader : public Reader {
+public:
+    explicit StringReader(const std::string &s);
+    ~StringReader() override;
+
+    int readByte() override;
+    bool readBytes(uint8_t* buf, size_t len) override;
+    std::string readString(size_t len) override;
+
+private:
+    std::istringstream in;
+};