diff --git a/include/of_util.h b/include/of_util.h
index e85d023..bbac325 100644
--- a/include/of_util.h
+++ b/include/of_util.h
@@ -38,10 +38,12 @@ private:
 template <typename T> std::shared_ptr<T> OfSingleton<T>::instance = nullptr;
 template <typename T> std::once_flag OfSingleton<T>::init_flag;
 
-class OfUtil {
+class OfUtil
+{
 public:
     OfUtil();
     ~OfUtil();
+
 public:
     static ofString now_time();
 };
@@ -231,4 +233,17 @@ private:
     std::condition_variable cv_;
 };
 
+class CCodec
+{
+public:
+    CCodec() = default;
+    ~CCodec() = default;
+
+public:
+#ifdef _WIN32
+    static std::string u8ToGBK(const std::string& str);
+    static std::string GBKTou8(const std::string& str);
+#endif
+};
+
 }   // namespace ofen
diff --git a/src/of_util.cpp b/src/of_util.cpp
index f5bbdc5..ea3bbf8 100644
--- a/src/of_util.cpp
+++ b/src/of_util.cpp
@@ -3,6 +3,10 @@
 #include <iomanip>
 #include <sstream>
 
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
 namespace ofen {
 void CMutBuffer::push(const char* data, int len)
 {
@@ -27,7 +31,11 @@ void CMutBuffer::remove_of(int start_pos, int len)
     if (start_pos < 0 || start_pos >= static_cast<int>(buffer_.size()) || len <= 0) {
         return;
     }
+#ifdef _WIN32
+    auto end_pos = min(start_pos + len, static_cast<int>(buffer_.size()));
+#else
     auto end_pos = std::min(start_pos + len, static_cast<int>(buffer_.size()));
+#endif
     buffer_.erase(buffer_.begin() + start_pos, buffer_.begin() + end_pos);
 }
 
@@ -66,4 +74,44 @@ ofString OfUtil::now_time()
     oss << std::put_time(&tm_now, "%Y-%m-%d %H:%M:%S");
     return oss.str();
 }
+
+#ifdef _WIN32
+std::string CCodec::u8ToGBK(const std::string& str)
+{
+    int wideCharLen = MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, nullptr, 0);
+    if (wideCharLen <= 0) {
+        return "";
+    }
+    std::wstring wideStr(wideCharLen, L'\0');
+    MultiByteToWideChar(CP_UTF8, 0, str.c_str(), -1, &wideStr[0], wideCharLen);
+    int gbkLen = WideCharToMultiByte(CP_ACP, 0, wideStr.c_str(), -1, nullptr, 0, nullptr, nullptr);
+    if (gbkLen <= 0) {
+        return "";
+    }
+    std::string gbkStr(gbkLen, '\0');
+    WideCharToMultiByte(CP_ACP, 0, wideStr.c_str(), -1, &gbkStr[0], gbkLen, nullptr, nullptr);
+
+    gbkStr.resize(gbkLen - 1);
+    return gbkStr;
+}
+std::string CCodec::GBKTou8(const std::string& str)
+{
+    int wideCharLen = MultiByteToWideChar(CP_ACP, 0, str.c_str(), -1, nullptr, 0);
+    if (wideCharLen <= 0) {
+        return "";
+    }
+    std::wstring wideStr(wideCharLen, L'\0');
+    MultiByteToWideChar(CP_ACP, 0, str.c_str(), -1, &wideStr[0], wideCharLen);
+
+    int utf8Len = WideCharToMultiByte(CP_UTF8, 0, wideStr.c_str(), -1, nullptr, 0, nullptr, nullptr);
+    if (utf8Len <= 0) {
+        return "";
+    }
+    std::string utf8Str(utf8Len, '\0');
+    WideCharToMultiByte(CP_UTF8, 0, wideStr.c_str(), -1, &utf8Str[0], utf8Len, nullptr, nullptr);
+
+    utf8Str.resize(utf8Len - 1);
+    return utf8Str;
+}
+#endif
 }   // namespace ofen