diff --git a/CMakeLists.txt b/CMakeLists.txt
index a107da8..aec08ea 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,6 +25,7 @@ set(CPPREG_API_HEADERS
     register/Mask.h
     register/Overflow.h
     register/Register.h
+    register/RegisterPack.h
     register/ShadowValue.h
     register/Traits.h)
 
diff --git a/register/Register.h b/register/Register.h
index b98ca27..a964acd 100644
--- a/register/Register.h
+++ b/register/Register.h
@@ -124,120 +124,6 @@ namespace cppreg {
     };
 
 
-    //! Register pack base implementation.
-    /**
-     * @tparam PackBase Base address to use for the pack memory.
-     * @tparam PackByteSize Size in bytes of the memory region for the pack.
-     */
-    template <
-        Address_t PackBase,
-        std::uint32_t PackByteSize
-    > struct RegisterPack {
-
-        //! Type alias for byte array.
-        using mem_array_t = std::array<volatile std::uint8_t, PackByteSize>;
-
-        //! Base address.
-        constexpr static const Address_t pack_base = PackBase;
-
-        //! Pack size in bytes.
-        constexpr static const std::uint32_t size_in_bytes = PackByteSize;
-
-        //! Reference to the byte array.
-        /**
-         * This is explicitly defined below.
-         */
-        static mem_array_t& _mem_array;
-
-    };
-
-    //! RegisterPack byte array reference definition.
-    template <
-        Address_t PackBase,
-        std::uint32_t PackByteSize
-    >
-    typename RegisterPack<PackBase, PackByteSize>::mem_array_t&
-        RegisterPack<PackBase, PackByteSize>::_mem_array =
-        *(
-            reinterpret_cast<
-                RegisterPack<PackBase, PackByteSize>::mem_array_t* const
-                >(RegisterPack<PackBase, PackByteSize>::pack_base)
-        );
-
-
-    //! Packed register implementation.
-    /**
-     * @tparam RegisterPack Pack to which the register belongs.
-     * @tparam RegWidth Register total width in bits.
-     * @tparam OffsetInPack Register offset in the pack in bytes.
-     * @tparam reset Register reset value (0x0 if unknown).
-     * @tparam shadow Boolean flag to enable shadow value (enabled if `true`).
-     *
-     * This implementation is intended to be used when defining a register
-     * that belongs to a type.
-     */
-    template <
-        typename RegisterPack,
-        Width_t RegWidth,
-        std::uint32_t OffsetInPack,
-        typename RegisterType<RegWidth>::type ResetValue = 0x0,
-        bool UseShadow = false
-    >
-    struct PackedRegister :
-    Register<
-        RegisterPack::pack_base + OffsetInPack * 8,
-        RegWidth,
-        ResetValue,
-        UseShadow
-            > {
-
-        //! Register type.
-        using base_reg = Register<
-            RegisterPack::pack_base + OffsetInPack * 8,
-            RegWidth,
-            ResetValue,
-            UseShadow
-                                 >;
-
-        //! Memory modifier.
-        /**
-         * @return A reference to the writable register memory.
-         */
-        static typename base_reg::MMIO_t& rw_mem_device() {
-            return RegisterPack::_mem_array[OffsetInPack];
-        };
-
-        //! Memory accessor.
-        /**
-         * @return A reference to the read-only register memory.
-         */
-        static const typename base_reg::MMIO_t& ro_mem_device() {
-            return RegisterPack::_mem_array[OffsetInPack];
-        };
-
-        // Safety check to detect if are overflowing the pack.
-        static_assert((OffsetInPack + (RegWidth / 8u)) <=
-                      RegisterPack::size_in_bytes,
-                      "packed register is overflowing the pack");
-
-    };
-
-
-    //! Pack indexing structure.
-    /**
-     * @tparam T List of types (registers or fields) to index.
-     *
-     * This can be used to conveniently map indices over packed registers.
-     * The order in the variadic parameter pack will define the indexing
-     * (starting at zero).
-     */
-    template <typename... T>
-    struct PackIndexing {
-        template <std::size_t N>
-        using regs = typename std::tuple_element<N, std::tuple<T...>>::type;
-    };
-
-
 }
 
 
diff --git a/register/RegisterPack.h b/register/RegisterPack.h
new file mode 100644
index 0000000..e99bb5d
--- /dev/null
+++ b/register/RegisterPack.h
@@ -0,0 +1,158 @@
+//! Register pack implementation.
+/**
+ * @file      RegisterPack.h
+ * @author    Nicolas Clauvelin (nclauvelin@sendyne.com)
+ * @copyright Copyright 2010-2018 Sendyne Corp. All rights reserved.
+ *
+ * This header provides the definitions related to register implementation.
+ */
+
+
+#include "Register.h"
+
+
+#ifndef CPPREG_REGISTERPACK_H
+#define CPPREG_REGISTERPACK_H
+
+
+//! cppreg namespace.
+namespace cppreg {
+
+
+    //! Register pack base implementation.
+    /**
+     * @tparam PackBase Base address to use for the pack memory.
+     * @tparam PackByteSize Size in bytes of the memory region for the pack.
+     */
+    template <
+        Address_t PackBase,
+        std::uint32_t PackByteSize
+    > struct RegisterPack {
+
+        //! Type alias for byte array.
+        using mem_array_t = std::array<volatile std::uint8_t, PackByteSize>;
+
+        //! Base address.
+        constexpr static const Address_t pack_base = PackBase;
+
+        //! Pack size in bytes.
+        constexpr static const std::uint32_t size_in_bytes = PackByteSize;
+
+        //! Reference to the byte array.
+        /**
+         * This is explicitly defined below.
+         */
+        static mem_array_t& _mem_array;
+
+    };
+
+    //! RegisterPack byte array reference definition.
+    template <
+        Address_t PackBase,
+        std::uint32_t PackByteSize
+    >
+    typename RegisterPack<PackBase, PackByteSize>::mem_array_t&
+        RegisterPack<PackBase, PackByteSize>::_mem_array =
+        *(
+            reinterpret_cast<
+                RegisterPack<PackBase, PackByteSize>::mem_array_t* const
+                >(RegisterPack<PackBase, PackByteSize>::pack_base)
+        );
+
+
+    //! Packed register implementation.
+    /**
+     * @tparam RegisterPack Pack to which the register belongs.
+     * @tparam RegWidth Register total width in bits.
+     * @tparam OffsetInPack Register offset in the pack in bytes.
+     * @tparam reset Register reset value (0x0 if unknown).
+     * @tparam shadow Boolean flag to enable shadow value (enabled if `true`).
+     *
+     * This implementation is intended to be used when defining a register
+     * that belongs to a type.
+     */
+    template <
+        typename RegisterPack,
+        Width_t RegWidth,
+        std::uint32_t OffsetInPack,
+        typename RegisterType<RegWidth>::type ResetValue = 0x0,
+        bool UseShadow = false
+    >
+    struct PackedRegister :
+        Register<
+            RegisterPack::pack_base + OffsetInPack * 8,
+            RegWidth,
+            ResetValue,
+            UseShadow
+                > {
+
+        //! Register type.
+        using base_reg = Register<
+            RegisterPack::pack_base + OffsetInPack * 8,
+            RegWidth,
+            ResetValue,
+            UseShadow
+                                 >;
+
+        //! Memory modifier.
+        /**
+         * @return A reference to the writable register memory.
+         */
+        static typename base_reg::MMIO_t& rw_mem_device() {
+            return RegisterPack::_mem_array[OffsetInPack];
+        };
+
+        //! Memory accessor.
+        /**
+         * @return A reference to the read-only register memory.
+         */
+        static const typename base_reg::MMIO_t& ro_mem_device() {
+            return RegisterPack::_mem_array[OffsetInPack];
+        };
+
+        // Safety check to detect if are overflowing the pack.
+        static_assert((OffsetInPack + (RegWidth / 8u)) <=
+                      RegisterPack::size_in_bytes,
+                      "packed register is overflowing the pack");
+
+    };
+
+
+    //! Pack indexing structure.
+    /**
+     * @tparam T List of types (registers or fields) to index.
+     *
+     * This can be used to conveniently map indices over packed registers.
+     * The order in the variadic parameter pack will define the indexing
+     * (starting at zero).
+     */
+    template <typename... T>
+    struct PackIndexing {
+        template <std::size_t N>
+        using regs = typename std::tuple_element<N, std::tuple<T...>>::type;
+    };
+
+
+    //! Template for loop implementation.
+    template <std::size_t start, std::size_t end>
+    struct for_loop {
+        template <template <std::size_t> class Op, typename T = void>
+        inline static void iterate(
+            typename std::enable_if<start < end, T>::type* = nullptr
+                                  ) {
+            Op<start>()();
+            if (start < end)
+                for_loop<start + 1, end>::template iterate<Op>();
+        };
+        template <template <std::size_t> class Op, typename T = void>
+        inline static void iterate(
+            typename std::enable_if<start >= end, T>::type* = nullptr
+                                  ) {};
+    };
+
+
+
+}
+
+
+#endif  // CPPREG_REGISTERPACK_H
diff --git a/single/cppreg-all.h b/single/cppreg-all.h
index a677303..6bee646 100644
--- a/single/cppreg-all.h
+++ b/single/cppreg-all.h
@@ -381,6 +381,13 @@ namespace cppreg {
         static_assert(RegWidth != 0u,
                       "defining a Register type of width 0u is not allowed");
     };
+}
+#endif  
+
+// RegisterPack.h
+#ifndef CPPREG_REGISTERPACK_H
+#define CPPREG_REGISTERPACK_H
+namespace cppreg {
     template <
         Address_t PackBase,
         std::uint32_t PackByteSize
@@ -404,12 +411,22 @@ namespace cppreg {
     template <
         typename RegisterPack,
         Width_t RegWidth,
-        std::uint32_t OffsetInPack
+        std::uint32_t OffsetInPack,
+        typename RegisterType<RegWidth>::type ResetValue = 0x0,
+        bool UseShadow = false
     >
     struct PackedRegister :
-    Register<RegisterPack::pack_base + OffsetInPack * 8, RegWidth> {
+        Register<
+            RegisterPack::pack_base + OffsetInPack * 8,
+            RegWidth,
+            ResetValue,
+            UseShadow
+                > {
         using base_reg = Register<
-            RegisterPack::pack_base + OffsetInPack * 8, RegWidth
+            RegisterPack::pack_base + OffsetInPack * 8,
+            RegWidth,
+            ResetValue,
+            UseShadow
                                  >;
         static typename base_reg::MMIO_t& rw_mem_device() {
             return RegisterPack::_mem_array[OffsetInPack];
@@ -421,12 +438,25 @@ namespace cppreg {
                       RegisterPack::size_in_bytes,
                       "packed register is overflowing the pack");
     };
-    template <typename... Regs>
+    template <typename... T>
     struct PackIndexing {
         template <std::size_t N>
-        using type = typename std::tuple_element<N, std::tuple<Regs...>>::type;
-        template <std::size_t N>
-        using regs = typename std::tuple_element<N, std::tuple<Regs...>>::type;
+        using regs = typename std::tuple_element<N, std::tuple<T...>>::type;
+    };
+    template <std::size_t start, std::size_t end>
+    struct for_loop {
+        template <template <std::size_t> class Op, typename T = void>
+        inline static void iterate(
+            typename std::enable_if<start < end, T>::type* = nullptr
+                                  ) {
+            Op<start>()();
+            if (start < end)
+                for_loop<start + 1, end>::template iterate<Op>();
+        };
+        template <template <std::size_t> class Op, typename T = void>
+        inline static void iterate(
+            typename std::enable_if<start >= end, T>::type* = nullptr
+                                  ) {};
     };
 }
 #endif